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Chapter 1 MULTIPLE CHOICE QUESTIONS Topic: Atomic Orbitals 1. A) B) C) D) E) In quantum mechanics a node (nodal surface or plane) is: a place where Ψ is negative. a place where Ψ is positive. a place where Ψ = 0. a place where Ψ2 is large. a place where Ψ2 is negative. Ans: C Topic: Atomic Orbitals, Molecular Orbitals 2. When the 1s orbitals of two hydrogen atoms combine to form a hydrogen molecule, how many molecular orbitals are formed? A) 1 B) 2 C) 3 D) 4 E) 5 Ans: B Topic: Atomic Orbitals 3. Which principle(s) or rule must be used to determine the correct electronic configuration for carbon in its ground state? A) Aufbau Principle B) Hund's Rule C) Pauli Exclusion Principle D) (A) and (B) only E) All three Ans: E 1 Chapter 1 Topic: Atomic Orbitals, Bonding 4. What point on the potential energy diagram below represents the most stable state for the hydrogen molecule? A) B) C) D) E) I II III IV V Ans: C Topic: Atomic Orbitals, Molecular Orbitals 5. A) B) C) D) E) According to molecular orbital theory, which molecule could not exist? H2 He2 Li2 F2 N2 Ans: B Topic: Atomic Orbitals, Molecular Orbitals 6. When the ls orbitals of two hydrogen atoms combine to form a hydrogen molecule, which molecular orbitals are formed? A) One bonding molecular orbital only B) Two bonding molecular orbitals C) One bonding molecular orbital and one antibonding molecular orbital D) Two antibonding molecular orbitals E) Three bonding molecular orbitals Ans: C 2 Chapter 1 Topic: Atomic Orbitals, Hybridization 7. The following electron configuration represents _______. A) B) C) D) E) 1s 2sp3 2sp3 2sp3 2sp3 the ground state of boron. the sp3 hybridized state of carbon. the sp3 hybridized state of nitrogen. the ground state of carbon. an excited state of carbon. Ans: C Topic: Atomic Orbitals, Molecular Orbitals 8. According to molecular orbital theory, in the case of a carbon-carbon double bond, the carbon-carbon bonding electrons of higher energy occupy this molecular orbital. A) σ bonding MO B) π bonding MO C) σ* antibonding MO D) π* antibonding MO E) π* bonding MO Ans: B Topic: Atomic Orbitals, Hybridization 9. A) B) C) D) E) Identify the atomic orbitals in the C-C sigma bond in ethyne. (2sp2, 2sp2) (2sp3, 2sp3) (2sp, 2sp) (2p, 2p) (2sp, 1s) Ans: C 3 Chapter 1 Topic: Lewis Structures, Formal Charges 10. Listed below are electron dot formulas for several simple molecules and ions. All valence electrons are shown; however, electrical charges have been omitted deliberately. A) B) C) D) E) H : Be : H H .. H:B:H .. H H .. H:N:H .. H .. H:N:H .. H H .. H:O:H .. I II III IV V Which of the structures actually bear(s) a positive charge? I II III III & V IV & V Ans: E Topic: Lewis Structures, Formal Charges 11. What is the formal charge on oxygen in the following structure? .. H3C O CH3 CH3 A) B) C) D) E) +2 +1 0 -1 -2 Ans: B 4 Chapter 1 Topic: Lewis Structures, Formal Charges 12. In which structure(s) below does the oxygen have a formal charge of +1? .. H O H H .. .. O: C O H H I .. H II .. H H3C O CH3 CH3 III IV s A) B) C) D) E) I only II only I and III I and IV I, III, and IV Ans: E Topic: Lewis Structures, Formal Charges 13. Which structure(s) contain(s) an oxygen that bears a formal charge of +1? .. .. :O :O .. .. .. .. : O C O: H C H3C O H H3C O CH3 C :O :O ..: ..: : O ..: CH3 H I II III IV V A) B) C) D) E) I and II III and IV V II I and V Ans: B 5 Chapter 1 Topic: Lewis Structures, Formal Charges 14. Which of the following molecules or ions has a nitrogen with a formal charge of -1? (Charges on ions have been omitted.) .. A) : N H H B) H C) H .. N .H. N H D) H3C H CH3 .. N H E) H3C C Ans: A CH3 N: Topic: Lewis Structures, Formal Charges 15. In which structure(s) below does nitrogen have a formal charge of +1? H3C N CH2 H3C .. N .. H .. H N H .. .OH . .. H3C NH2 H I A) B) C) D) E) .. H3C N CH3 II III I II and IV III and V I and V V Ans: A 6 IV V CH3 Chapter 1 Topic: Lewis Structures, Formal Charges 16. Which of the following is an ion with a single negative charge? .. A) H3C O : . . .. . .. . B) : O N O : .. .. C) : O: .. :O N :O ..: D) All of these E) None of these Ans: D Topic: Lewis Structures, Formal Charges 17. Which of these is a correct electron-dot representation of the nitrite ion, NO2-? .. .. .. .. .. .. .. : :O : N : : O O : : N : : : O : : N : O : .. .O. .. .. .. .. I A) B) C) D) E) III II .. .. .. :O:N:O: .. .. .. .. .. :O::N:O .. .. IV V I II III IV V Ans: A 7 Chapter 1 Topic: Lewis Structures, Formal Charges 18. Which is NOT a correct Lewis structure? .. A) H N F : .. H H B) H C C) H .H. O .. D) H .. .O. .. F: .. .. O H . .. . :O H B :O .. H E) None of these Ans: A Topic: Lewis Structures, Formal Charges 19. Listed below are electron dot formulas for several simple molecules and ions. All valence electrons are shown; however, electrical charges have been omitted deliberately. A) B) C) D) E) H : Be : H H .. H:B:H .. H H .. H:N:H .. H .. H:N:H .. H H .. H:O:H .. I II III IV V Which of the structures is negatively charged? I II III IV V Ans: B 8 Chapter 1 Topic: Lewis Structures, Formal Charges 20. Which compound contains a nitrogen atom with a formal positive charge? A) B) C) D) E) N H N N I II III I II III More than one of the above None of the above Ans: D Topic: Lewis Structures 21. Considering Lewis structures, which of these compounds possesses a single unpaired electron? A) N2 B) N2O C) NO D) N2O4 E) O2 Ans: C Topic: Lewis Structures .. 22. Z Y A) B) C) D) E) .. Y is a generalized structural representation which can be used for all of the following, except: OF2 NH2– H2S BeBr2 There is no exception Ans: D 9 Chapter 1 Topic: Lewis Structures, Formal Charges 23. In which of these cases does the central atom have a zero formal charge? A) HFH H B) C) H3C O F F B CH3 F F H D) H3C N CH3 H CH3 E) H3C C CH3 CH3 Ans: E Topic: Lewis Structures, Formal Charges 24. The formal charge on sulfur in sulfuric acid is: O H O S O H O A) B) C) D) E) 0 -1 +1 -2 +2 Ans: A Topic: Lewis Structures, Formal Charges 25. ExpAns:ion of the valence shell to accommodate more than eight electrons is possible with: A) Fluorine B) Nitrogen C) Carbon D) Sulfur E) Beryllium Ans: D 10 Chapter 1 Topic: Lewis Structures, Molecular Geometry 26. A) B) C) D) E) Based on VSEPR theory, which of the following would have a trigonal planar shape? CH3)3N HCN NH4+ CH3− CH3+ Ans: E Topic: Lewis Structures, Molecular Geometry 27. A) B) C) D) E) VSEPR theory predicts an identical shape for all of the following, except: NH3 H3O+ BH3 CH3All have the same geometry Ans: C Topic: Lewis Structures, Molecular Geometry 28. A) B) C) D) E) What shape does the methyl cation, CH3+, have? Octahedral Tetrahedral Trigonal planar Linear Trigonal pyramidal Ans: C 11 Chapter 1 Topic: Lewis Structures, Molecular Geometry : : 29. Which of the structures below would be trigonal planar (a planar triangle)? (Electrical charges have been deliberately omitted.) F F H .. .. .. .. .. .. :F : N : : H:O:H H:C: B .. .. .. .. . . : .F. H F F H .. .. .. .. .. : .. .. : .. I A) B) C) D) E) II IV III I II III IV I and IV Ans: A Topic: Lewis Structures, Molecular Geometry 30. Which of the following would have a trigonal planar (or triangular) structure? A) B) C) D) E) : CH3 : CH3 : NH3 BH3 : OH3 I II III IV V I, II, and IV II and IV IV II, IV, and V All of these Ans: B Topic: Molecular Geometry 31. A) B) C) D) E) What bond angle is associated with a tetrahedral molecule? 120° 109.5° 180° 90° 45° Ans: B 12 Chapter 1 Topic: Molecular Geometry 32. A) B) C) D) E) What would be the spatial arrangement of the atoms of the methyl anion, :CH3-? Octahedral Tetrahedral Trigonal planar Linear Trigonal pyramidal Ans: E Topic: Lewis Structures, Molecular Geometry 33. A) B) C) D) E) Which of these structures would be a perfectly regular tetrahedron? CH3Br CH2Br2 CHBr3 CBr4 More than one of these Ans: D Topic: Lewis Structures, Molecular Geometry 34. Which molecule would be linear? (In each case you should write a Lewis structure before deciding.) A) SO2 B) HCN C) H2O2 D) H2S E) OF2 Ans: B Topic: Lewis Structures, Molecular Geometry 35. A) B) C) D) E) The bond angles in PH3 would be expected to be approximately: 60° 90° 105° 109° 120° Ans: C 13 Chapter 1 Topic: Periodic Properties, Electronegativity 36. A) B) C) D) E) Select the most electronegative element. H O N B C Ans: N Topic: Atomic Orbitals, Hybridization 37. Select the hybridized atomic orbital. I A) B) C) D) E) II III IV V I II III IV V Ans: C Topic: Atomic Orbitals, Hybridization 38. How many 2p atomic orbitals from boron must be mixed with a 2s atomic orbital to yield the bonding hybrid atomic orbitals in BF3? A) 1 B) 2 C) 3 D) 4 E) 5 Ans: B 14 Chapter 1 Topic: Atomic Orbitals, Hybridization 39. A) B) C) D) E) In which molecule is the central atom sp3 hybridized? CH4 NH3 H2O All of these None of these Ans: D Topic: Atomic Orbitals, Hybridization 40. In which of the following would you expect the central atom to be sp3 hybridized (or approximately sp3 hybridized)? A) BH4B) NH4+ C) CCl4 D) CH3:E) All of these Ans: D Topic: Atomic orbitals, hybridization 41. A) B) C) D) E) Which compound has the shortest carbon-carbon bond(s)? CH3CH3 CH2=CH2 HC≡CH CH3CH2CH3 All carbon-carbon bonds are the same length. Ans: C Topic: Atomic Orbitals, Hybridization 42. A) B) C) D) E) Which of the following contains an sp2-hybridized carbon? CH4 CH3:− CH3CH3 CH3+ HC≡CH Ans: D 15 Chapter 1 Topic: Atomic Orbitals, Hybridization 43. Which is the shortest of the carbon-carbon single bonds indicated by arrows in the following compounds? A) H3C CH3 H3C C H3C CH B) C) CH CH2 D) HC C C CH E) H2C HC C CH Ans: D Topic: Atomic Orbitals, Hybridization 44. A) B) C) D) E) How many sigma (1s-2sp3) bonds are there in ethane? 7 6 5 3 1 Ans: B Topic: Atomic Orbitals, Bonding 45. A) B) C) D) E) Which of these substances contains both covalent and ionic bonds? NH4Cl H2O2 CH4 HCN H2S Ans: A 16 Chapter 1 Topic: Atomic Orbitals, Periodic Trends, Electronegativity 46. A) B) C) D) E) The greatest degree of ionic character is anticipated for the bond between: H and C H and Cl C and Cl H and Br Br and Cl Ans: B Topic: Atomic Orbitals, Hybridization 47. A) B) C) D) Which molecule contains an sp-hybridized carbon? HCN CH2=CH2 CH3Cl H C O H E) CH3CH3 Ans: A Topic: Atomic Orbitals, Lewis structures, Resonance 48. Which of the structures below is not expected to contribute to the CO2 resonance hybrid? A) B) O C O O C C O O C) O D) E) O O C C O O Ans: D 17 Chapter 1 Topic: Atomic orbitals, Lewis structures, resonance .. : .. 49. Which of the following could not be a resonance structure of CH3NO2? A) H O H C N .. .O. H O .. B) : H H C C N +2 O O H .. : .. H : O .. .. H .. .. D) H : H O H .. : .. C) N C N.. O .. E) Both C and D Ans: D H H Topic: Atomic Orbitals, Lewis Structures, Resonance O : : : C : : : : : 50. Which of the following pairs are NOT resonance structures? A) and H3C O N O : H3C O N O : : .. .. O .. and O : C .. .. O : : B) .. .. : : H3C : C) O N O: O and H3C N .. : .. : O D) Each of these pairs represents resonance structures. E) None of these pairs represents resonance structures. Ans: C 18 Chapter 1 Topic: Atomic Orbitals, Lewis Structures, Resonance 51. How many resonance structures can be written for the NO3- ion in which the nitrogen atom bears a formal charge of +1? A) 1 B) 2 C) 3 D) 4 E) 5 Ans: C Topic: Empirical and Molecular Formulas 52. A) B) C) D) E) What is the empirical formula for cyclohexane? (Its molecular formula is C6H12.) CH CH2 C2H4 C6H6 C2H2 Ans: B Topic: Empirical and Molecular Formulas 53. A compound has the empirical formula, CCl. Its molecular weight is 285 +/- 5. What is the molecular formula for the compound? A) C2Cl2 B) C3Cl3 C) C4Cl4 D) C5Cl5 E) C6Cl6 Ans: E Topic: Empirical and Molecular Formulas 54. A compound consists only of carbon, hydrogen and oxygen. Elemental analysis gave: C, 70.5%, H, 13.8%. The molecular weight of the compound was found to be 103 +/- 3. What is the molecular formula for the compound? A) C6H12O B) C5H12O2 C) C3H2O4 D) C3H6O3 E) C6H14O Ans: E 19 Chapter 1 Topic: Isomerism 55. Which of the following is a set of constitutional isomers? Br Br I A) B) C) D) E) Br II Br III IV I and II II and III I, II, and III II, III, and IV I, III, and IV Ans: E Topic: General 56. Credit for the first synthesis of an organic compound from an inorganic precursor is usually given to: A) Berzelius B) Arrhenius C) Kekule D) Wohler E) Lewis Ans: D Topic: Isomerism 57. A) B) C) D) E) CH3CH2OCH2CH3 and CH3CH2CH2CH2OH are examples of what are now termed: Structural isomers Resonance structures Functional isomers Empirical isomers Constitutional isomers Ans: E 20 Chapter 1 Topic: Hybridization 58. What is the approximate hybridization state of the oxygen molecule in ethanol, C2H5OH? A) sp B) sp2 C) sp3 D) p3 E) d2sp3 Ans: C Topic: Hybridization 59. What is the approximate hybridization state of the oxygen molecule in trimethylamine, (CH3)3N? A) sp B) sp2 C) sp3 D) p3 E) d2sp3 Ans: C Topic: Lewis structures, Hybridization 60. Which molecule has a non-linear structure (i.e., for which molecule are the nuclei not in a straight line)? A) O=C=O B) H–O–H C) H–Cl D) H–C≡N E) H–C≡C–H Ans: B 21 Chapter 1 Topic: Isomerism 61. Which of the following structures represent compounds that are constitutional isomers of each other? I A) B) C) D) E) II III IV I and II I and III I, II, and III I, II, III, and IV II and III Ans: C Topic: Isomerism 62. Which compound is not an isomer of the others? OH O O OH I A) B) C) D) E) II III I II III IV All of the above are isomers of each other. Ans: A 22 IV Chapter 1 Topic: Isomerism 63. Consider the following: A) B) C) D) E) CH3CH2CH=CHCH2CH3 I CH3CH2CH2CH2CH=CH2 II CH3CH=CHCH2CH2CH3 III CH2=CHCH2CH2CH2CH3 IV Which two structures represent the same compound? I and II II and III I and III II and IV None of these Ans: D Topic: Isomerism 64. Consider the following: A) B) C) D) E) CH3CH2CH2CH=CHCH2CH2CH3 I CH3CH2CH2CH2CH2CH2CH=CH2 II CH3CH2CH=CHCH2CH2CH2CH3 III CH2=CHCH2CH2CH2CH2CH2CH3 IV Which structures can exist as cis-trAns: isomers? I and II I and III I and IV II and III I alone Ans: B 23 Chapter 1 Topic: Isomerism 65. Which of the following represent a pair of constitutional isomers? A) and B) CH3CH=CH2 and CH2=CHCH3 Br Br C) Br H H Br D) H and Br H Br H Br H and H H Br E) More than one of these Ans: E Topic: Isomerism 66. Which of the following represent pairs of constitutional isomers? OH O A) O and Br H Br CH3 H and Br H CH2 C) O CH3 CH3 B) H Br H and H CH3 D) More than one of these pairs E) All of these pairs Ans: D Topic: Isomerism 67. A) B) C) D) E) Cis-trAns: isomerism is possible only in the case of: CH2=CBr2 CH2=CHBr BrCH=CHBr Br2C=CHBr Br2C=CBr2 Ans: C 24 Chapter 1 Topic: Atomic orbitals, molecular orbitals 68. When the 1s orbitals of two hydrogen atoms combine to form a hydrogen molecule, how are the electrons distributed in the resulting molecular orbitals? A) 2 electrons in the bonding molecular orbital B) 1 electron in the bonding molecular orbital, 1 electron in the non-bonding molecular orbital C) 1 electron in the bonding molecular orbital, 1 electron in the antibonding molecular orbital D) 2 electrons in the non-bonding molecular orbital E) 2 electrons in the antibonding molecular orbital Ans: A Topic: Atomic Orbitals, Electron Configuration, Hybridization 69. The following electron configuration represents: A) B) C) D) E) 1s 2sp3 2sp3 2sp3 2sp3 The ground state of nitrogen The ground state of oxygen The sp3 hybridized state of carbon The excited state of oxygen None of the above correctly identifies the given electron configuration Ans: E Topic: Atomic Orbitals, Hybridization, Bonding 70. Identify the atomic orbitals involved in the C-2---C-3 sigma bond (indicated by an arrow) in the following molecule: 1 4 2 6 7 A) B) C) D) E) 5 2 3 2 sp , sp sp2, sp sp2, sp3 sp3, sp2 sp, sp2 Ans: E 25 Chapter 1 Topic: Lewis Structures 71. A) B) C) D) E) In which of the following does the central atom have 2 pairs of non-bonding electrons? O3 CO2 CO3 2− NH4+ H2S Ans: E Topic: Molecular Geometry 72. Based on the VSEPR theory, which of the following would have a tetrahedral arrangement of electrons around the central atom? A) BH3 B) NO2 − C) SiH4 D) CO3 2− E) SO3 Ans: C Topic: Molecular Geometry 73. A) B) C) D) E) What would be the spatial arrangement of the atoms of the ozone molecule (O3)? Linear Angular Trigonal planar Trigonal pyramidal Tetrahedral Ans: B Topic: Periodic Trends, Electronegativity 74. A) B) C) D) E) Select the least electronegative element P N Mg Si K Ans: E 26 Chapter 1 Topic: Atomic Orbitals, Hybridization 75. In which molecule(s) can the molecular geometry be attributed to an sp2 hybridized central atom? A) PBr3 B) CH4 C) CHCl3 D) HNO2 E) None of the above has an sp2 hybridized central atom Ans: D Topic: Bonding, Atomic Orbitals, Hybridization 76. Which molecule has the shortest carbon-carbon single bond? I II III IV A) B) C) D) E) V I II III IV V Ans: E Topic: Atomic Orbitals, Hybridization 77. How many s-sp2 bonds are there in the following substance? A) B) C) D) E) 2 3 4 5 12 Ans: B 27 Chapter 1 Topic: Atomic Orbitals, Hybridization 78. How many s-sp3 bonds are there in the following substance? A) B) C) D) E) 3 8 12 13 16 Ans: D Topic: Resonance 79. A) B) C) D) E) Which of the following species exhibits resonance stabilization? H2SO4 O3 CO2 CCl4 None of the above species exhibit resonance Ans: B SHORT ANS:WER QUESTIONS Topic: General 80. Organic compounds were originally defined as compounds obtained from __________. Ans: living sources/organisms Topic: General 81. The modern definition of organic chemistry is _________________. Ans: the study of carbon compounds Topic: General 82. Different compounds with the same molecular formula are referred to as __________. Ans: isomers 28 Chapter 1 Topic: General 83. Constitutional isomers differ in the _________________. Ans: connectivity of their atoms Topic: General 84. The bond that results when two atoms share a pair of electrons is called a _________________. Ans: covalent bond Topic: Atomic orbitals 85. Define an orbital. Ans: a region of space where the probability of finding an electron is high Topic: Atomic orbitals 86. An orbital is defined as a region of space where the probability of _________________ is high. Ans: finding an electron Topic: Atomic orbitals 87. There are three fundamental rules that we use in writing electronic configurations for atoms and molecules. The configuration shown below (for oxygen) violates one of these rules. Which one? 1s 2s 2p 2p Ans: Pauli exclusion principle 2p Topic: Molecular orbitals 88. When atomic orbitals of opposite phase overlap a(n) _________________ molecular orbital is formed. Ans: antibonding Topic: Molecular orbitals 89. When atomic orbitals of the same phase overlap a(n) _________________ molecular orbital is formed. Ans: bonding 29 Chapter 1 Topic: Lewis Structures 90. Draw the Lewis structure of the nitrite ion, NO2− , clearly indicating resonance contributors as well as non-bonding pairs of electrons and formal charges, as relevant. Ans: O . . .. .O . . .. . .. N .. . .. .. . .O . . O . N Topic: Isomers, Bond-Line Formulas 91. Draw all the isomers of C4H9Br, using bond-line formulas. Br Ans: Br Br Br Topic: Isomers, Bond-Line Formulas 92. Draw all the isomers of C4H10O, using bond-line formulas. OH Ans: OH OH O O O Topic: Isomers, Bond-Line Formulas 93. Draw all isomers of C4H8, using bond-line formulas. Ans: 30 OH Chapter 1 Topic: Lewis Structures .. .. 94. Draw the Lewis structure of acetic acid, CH3CO2H, clearly indicating all non-bonding pairs of electrons. O Ans: H H C C . .O. . H H 31 Chapter 2 MULTIPLE CHOICE QUESTIONS Topic: Intermolecular forces 1. Which compound would you expect to have the lowest boiling point? NH2 A) B) NH2 C) H N D) N E) NH2 Ans: D : Topic: Molecular geometry, dipole moment 2. Which molecule would you expect to have no dipole moment (i.e., μ = 0 D)? A) CHF3 H B) F H C) :NF3 D) F H F F H E) CH2F2 Ans: B 32 Chapter 2 Topic: Intermolecular forces 3. A) B) C) D) Which of these compounds would have the highest boiling point? CH3OCH2CH2CH2OCH3 CH3CH2OCH2CH2OCH3 CH3CH2OCH2OCH2CH3 CH3OCH2CHOCH3 CH3 E) HOCH2CH2CH2CH2CH2OH Ans: E Topic: Intermolecular forces 4. Which of these would you expect to have the lowest boiling point? A) CH3CH2CH2OH B) CH3CHCH3 OH C) CH3OCH2CH3 D) CH3CH2CH2CH2OH E) CH3CH2OCH2CH3 Ans: C Topic: Intermolecular forces 5. A) B) C) D) E) Which compound would have the highest boiling point? CH3CH2CH2CH2CH2CH3 CH3CH2OCH2CH2CH3 CH3CH2CH2CH2CH2OH CH3CH2OCH(CH3)2 CH3OCH2CH2CH2CH3 Ans: C Topic: Intermolecular forces 6. Which of the following is not found in the following substance? CH3CH2CH2CH2CH2OH A) Ion-ion B) van der Waals C) Dipole-dipole D) Resonance E) Hydrogen bonding Ans: D 33 Chapter 2 Topic: Intermolecular forces 7. Which compound would you expect to have the lowest boiling point? O A) NH2 H N B) O O C) N D) NH2 O E) O N H Ans: C Topic: Intermolecular forces 8. A) B) C) D) E) Which compound would you expect to have the highest boiling point? CH3OCH2CH2OCH3 CH3OCH2OCH2CH3 HOCH2CH2CH2CH2OH CH3OCH2CH2CH2OH (CH3O)2CHCH3 Ans: C Topic: Molecular geometry, dipole moment 9. Which of the following would have no net dipole moment (μ = 0 D)? A) CBr4 B) cis-1,2-Dibromoethene C) trAns:-1,2-Dibromoethene D) 1,1-Dibromoethene E) More than one of these Ans: E 34 Chapter 2 Topic: Molecular geometry, dipole moment 10. Which molecule has dipole moment greater than zero? F A) F H B) F F C) F H H H H H F D) More than one of these E) None of these Ans: D Topic: Intermolecular forces 11. A) B) C) D) E) The strongest of attractive forces is which type? van der Waals Ion-dipole Dipole-dipole Cation-anion Hydrogen bonds Ans: D Topic: Intermolecular forces 12. A) B) C) Of the following compounds, the one with the highest boiling point is: CH3CH3 CH3CH2Cl CH3C=O H D) CH3CH2OH E) CH3CH2OCH2CH3 Ans: D 35 Chapter 2 Topic: Intermolecular forces 13. This alkane is predicted to have the highest melting point of those shown: A) CH3CH2CH2CH3 B) CH3CHCH3 CH3 C) CH3CH2CH2CH2CH3 D) CH3CHCH2CH3 E) CH3 CH3 CH3CCH3 CH3 Ans: E Topic: Intermolecular forces 14. The solid alkane CH3(CH2)18CH3 is expected to exhibit the greatest solubility in which of the following solvents? A) CCl4 B) CH3OH C) H2O D) CH3NH2 E) HOCH2CH2OH Ans: A 36 Chapter 2 Topic: Intermolecular forces 15. Which compound would have the lowest boiling point? OH OH O I II III OH OH IV A) B) C) D) E) V I II III IV V Ans: A Topic: Molecular geometry, Polarity 16. Which molecule(s) has dipole moment equal to zero? Cl A) B) Cl Cl C) Cl Cl D) Cl Cl Cl E) None of these have dipole moment equal to zero Ans: C 37 Chapter 2 Topic: Molecular geometry, polarity 17. A) B) C) D) E) Which molecule has a zero dipole moment? SO2 CO2 CO CHCl3 None of these Ans: B Topic: Molecular geometry, polarity 18. A) B) C) D) E) Which molecule has a zero dipole moment? CH3Cl CH2Cl2 CHCl3 CCl4 None of these Ans: D Topic: Molecular geometry, polarity 19. A) B) C) D) E) Which molecule would have a dipole moment greater than zero? BeCl2 BCl3 CO2 H2O CCl4 Ans: D Topic: Molecular geometry, polarity 20. For a molecule to possess a dipole moment, the following condition is necessary but not sufficient. A) Three or more atoms in the molecule B) Presence of one or more polar bonds C) A non-linear structure D) Presence of oxygen or fluorine E) Absence of a carbon-carbon double or triple bond Ans: B 38 Chapter 2 Topic: Molecular geometry, polarity 21. A) B) C) D) E) A non-zero dipole moment is exhibited by: SO2 CO2 CCl4 BF3 Cl Cl Cl Cl Ans: A Topic: Intermolecular forces 22. A) B) C) D) E) Which of these is the weakest of the intermolecular attractive forces? Ion-ion van der Waals Dipole-dipole Covalent bonding Hydrogen bonding Ans: B Topic: Functional groups 23. Which compound listed below is a secondary alcohol? A) CH3CHCH2CH3 OH B) CH3CHCH2OH C) CH3 CH3 CH3COH CH3 D) CH3CH2CH2CH2OH E) CH3CH2CH2OCH3 Ans: A 39 Chapter 2 Topic: Functional groups 24. Which compound is a secondary amine? A) CH3CH2CH2NH2 B) CH3CHCH3 NH2 C) CH3CH2NH CH3 D) H3C N CH3 CH3 E) CH3CH2CHNH2 CH3 Ans: C Topic: Functional groups 25. Which compound is an aldehyde? O O O NH O I II III O OH A) B) C) D) E) IV I II III IV V Ans: D V 40 Chapter 2 Topic: Functional groups 26. Which compound is a ketone? A) O C OH H O B) CH3CCH2CH3 C) O HCOCH3 D) O C H H E) H3C CH OH H3C Ans: B Topic: Functional groups 27. Which compound is an ester? O O O O NH I II III O OH IV A) B) C) D) E) V I II III IV V Ans: C 41 Chapter 2 Topic: Functional groups 28. The compound shown below is a synthetic estrogen. It is marketed as an oral contraceptive under the name Enovid. OH O A) B) C) D) E) In addition to an alkane (actually cycloalkane) skeleton, the Enovid molecule also contains the following functional groups: Ether, alcohol, alkyne. Aldehyde, alkene, alkyne, alcohol. Alcohol, carboxylic acid, alkene, alkyne. Ketone, alkene, alcohol, alkyne. Amine, alkene, ether, alkyne. Ans: D Topic: Functional Groups 29. Which is a 3° alkyl halide? F Br Cl I II III I Br IV A) B) C) D) E) V I II III IV V Ans: B 42 Chapter 2 Topic: Functional groups 30. Which is a 3° amine? NH2 H2N NH I II III NH2 O N IV A) B) C) D) E) V I II III IV V Ans: D Topic: Functional groups 31. Which functional group is not contained in prostaglandin E1? O O HO H A) B) C) D) E) H H OH H OH Prostaglandin E1 Ketone 2° alcohol 3° alcohol Carboxylic acid Alkene Ans: C 43 Chapter 2 Topic: Functional groups 32. The compound below is an adrenocortical hormone called cortisone. Which functional group is not present in cortisone? OH O O OH O A) B) C) D) E) 1° alcohol 2° alcohol 3° alcohol Ketone Alkene Ans: B Topic: Functional groups 33. The compound shown below is a substance called Capsaicin, found in varying concentrations in several varieties of hot peppers, and responsible for their respective degrees of “heat”. Which functional groups are present in the molecule of capsaicin? O N H O OH A) B) C) D) E) Capsaicin Alkene, ketone, amine, alcohol, ester Alkene, ketone, alcohol, ether Alkene, amine, phenol, ether Ether, phenol, alkene, amide Ester, phenol, alkene, amide Ans: D 44 Chapter 2 Topic: Functional groups 34. Drawn below is Atropine, found in Atropa belladonna, sometimes used in dilating pupils during an eye-exam. Which of the following functional groups is NOT in atropine? N O O OH Atropine A) B) C) D) E) Amine Ester Alcohol Benzene Ring Ketone Ans: E Topic: Functional groups 35. The compound shown below is the male sex hormone, testosterone. OH O O A) B) C) D) E) In addition to a cycloalkane skeleton, testosterone also contains the following functional groups: Alkene, ester, tertiary alcohol. Alkene, ether, secondary alcohol. Alkene, ketone, secondary alcohol. Alkyne, ketone, secondary alcohol. Alkene, ketone, tertiary alcohol. Ans: C 45 Chapter 2 Topic: Functional groups 36. Which is a carboxylic acid? OH O OH O O I O II III O O O OH IV A) B) C) D) E) V I II III IV V Ans: E Topic: Functional groups 37. Which compound is a tertiary alcohol? CH3 H3CH2C O OH H HO CH3 I II III O IV A) B) C) D) E) OH V I II III IV V Ans: E 46 Chapter 2 Topic: Functional groups 38. Which compound is a primary amine with the formula C5H13N? H2N NH H2N I II III N NH2 IV A) B) C) D) E) V I II III IV V Ans: C Topic: Functional groups 39. Which compound can be classified as an ester as well as a ketone? O O O O O O I II O III O O O OH OH IV A) B) C) D) E) O V I II III IV V Ans: D 47 Chapter 2 Topic: Functional groups 40. A) B) C) D) E) The C–O–C bond angle in diethyl ether is predicted to be approximately: 90º 105º 110º 120º 180º Ans: C Topic: Functional groups 41. Which compound(s) contain(s) tertiary carbon atom(s)? F I II III Br OH OH IV A) B) C) D) E) V I, II, III I II, III I, IV V Ans: D Topic: Isomers 42. The number of unique open-chain structures corresponding to the molecular formula C3H5Cl is: A) 2 B) 3 C) 4 D) 5 E) 6 Ans: C 48 Chapter 2 Topic: General, Bonding 43. The C4-C5 carbon-carbon bond in the following molecule results from the overlap of which orbitals ( in the order C4-C5) ? o 7 5 A) B) C) D) E) 1 3 4 6 2 sp–sp2 sp–sp3 sp2–sp2 sp2–sp3 sp3–sp2 Ans: E Topic: Functional groups 44. An example of a tertiary amine is: H N NH2 I II NH2 IV A) B) C) D) E) H2N III N V I II III IV V Ans: E 49 Chapter 2 Topic: Functional groups 45. Which functional groups are present in the following compound? A) B) C) D) E) Alkene, 1º alcohol, ketone Alkene, 2º alcohol, aldehyde Alkene, 2º alcohol, ketone Alkyne, 1º alcohol, aldehyde Alkyne, 2º alcohol, ketone Ans: B Topic: Functional groups, Isomerism 46. A) B) C) D) E) How many constitutional isomers are possible with the formula C4H10O? 3 4 5 6 7 Ans: E Topic: Functional groups 47. A tertiary carbon atom is present in which of these compounds? Cl I Cl II III OH HO IV A) B) C) D) E) V I II, IV III, V IV All of these Ans: C 50 Chapter 2 Topic: Functional groups 48. Which of these compounds is a secondary alkyl chloride? A) CH3CH2CH2CH2CH2Cl CH3 B) CH3CCH2CH3 Cl C) CH3CHCH2CH2CH3 Cl D) CH3CH2CHCl CH2CH3 E) Two of these Ans: E Topic: Functional groups, Isomerism 49. A) B) C) D) E) How many 2º alkyl bromides, neglecting stereoisomers, exist with the formula C6H13Br? 4 5 6 7 8 Ans: C 51 Chapter 2 Topic: Functional Groups 50. Many organic compounds contain more than one functional group. Which of the following is both an aldehyde and an ether? O O O O O I O II O III O O OCH3 O IV A) B) C) D) E) V I, II, IV V I, V III Ans: A Topic: IR Spectroscopy 51. An oxygen-containing compound shows strong IR absorption at 1630-1780 cm-1 and 3200-3550 cm-1. What type of compound is it likely to be? A) An alcohol B) A carboxylic acid C) An ether D) A ketone E) An aldehyde Ans: B Topic: IR Spectroscopy 52. The absorption band for the O-H stretch in the IR spectrum of an alcohol is sharp and narrow in the case of: A) a Nujol mull of the alcohol. B) a concentrated solution of the alcohol. C) a gas phase spectrum of the alcohol. D) the spectrum of the neat liquid E) none of these Ans: C 52 Chapter 2 Topic: IR Spectroscopy 53. A split peak for the IR absorption due to bond stretching is observed for the carbonyl group in which of these compounds? O A) CH3CH2CH2COH O B) CH3CH2CCl O C) ca CH3CH2CNH2 O D) CH3CH2COCH2CH3 O O E) CH3CH2COCCH2CH3 Ans: E Topic: IR Spectroscopy 54. A) B) C) D) E) The IR stretching frequency occurs at the lowest frequency for which of these bonds? C–H C–O C–Br C–N C–F Ans: C Topic: IR Spectroscopy 55. The IR stretching frequency can be expected to occur at the lowest frequency for which of these bonds? A) C–H B) O–H C) N–H D) S–H E) Difficult to predict Ans: D 53 Chapter 2 Topic: IR Spectroscopy 56. The IR stretching frequency can be predicted to occur at the highest frequency for which of these bonds? A) C–H B) C–F C) C–Cl D) C–Br E) C–I Ans: A Topic: IR Spectroscopy 57. A) B) C) D) E) An anticipated IR absorption band may not be observed because: it occurs outside the range of the instrument used. no change occurs in the dipole moment during the vibration. the absorption band is eclipsed by another. the intensity is so weak that it cannot be differentiated from instrument noise. All of these Ans: E Topic: IR Spectroscopy 58. IR evidence for the presence of the C=C would be most difficult to detect in the case of which of these alkenes? A) B) C) D) E) Ans: D 54 Chapter 2 Topic: IR Spectroscopy 59. The IR absorption due to the stretching of which of these carbon-hydrogen bonds occurs at the highest frequency? H H H I II III H IV A) B) C) D) E) H V I II III IV V Ans: E Topic: IR Spectroscopy 60. The IR spectrum of which type of compound will not show evidence of hydrogen bonding? A) Aldehyde B) Alcohol C) Carboxylic acid D) Phenol E) Primary amine Ans: A Topic: IR Spectroscopy 61. The IR spectrum of which type of compound generally exhibits evidence of hydrogen bonding? A) Aldehyde B) Carboxylic acid C) Alkene D) Ester E) Ketone Ans: B 55 Chapter 2 Topic: Intermolecular forces 62. The following substance is expected to have low solubility in which of the following solvent(s)? O Na O A) B) C) D) E) CCl4 C2H5OH CHCl3 CH2OHCH2CH2CH2CH2CH2OH The given substance is likely to be quite soluble in all of the solvents described Ans: A Topic: IR Spectroscopy 63. A) B) C) D) E) The IR stretching frequency occurs at the lowest frequency for which of these bonds? B–H O-H N-H S-H Difficult to predict Ans: D Topic: IR Spectroscopy 64. An oxygen-containing compound which shows sharp IR absorption at 2200 cm-1 and 3300 cm-1 is likely to be what type of compound? A) An ester B) An alkene C) An alkyne D) An ether E) An aldehyde Ans: B 56 Chapter 2 Topic: IR Spectroscopy 65. The IR spectrum of which of the following substances is likely to show a small, but sharp peak at 2200 cm-1? OH O N H II I IV A) B) C) D) E) III V I II III IV V Ans: E SHORT ANSWER QUESTIONS Topic: Functional Groups 66. Hydrocarbons containing carbon-carbon double bonds are referred to as ___________. Ans: alkenes Topic: Functional Groups, IR Spectroscopy 67. An IR spectrum has significant peaks at 2200 and 3300 cm-1. What functional group is present in the molecule? Ans: A terminal alkyne Topic: Functional Groups 68. A group in which a carbon atom has a double bond to an oxygen atom is called a __________. Ans: carbonyl 57 Chapter 2 Topic: Functional Groups, IR Spectroscopy 69. An IR spectrum has significant peaks at 3080 and 1650 cm-1. What functional group is present in the molecule? Ans: an alkene Topic: Functional Groups, IR Spectroscopy 70. Examine the following IR spectrum, for substance P (C8H22O). Which oxygen containing functional group is present in P? Ans: aldehyde Topic: Functional Groups, IR Spectroscopy 58 Chapter 2 71. Examine the following IR spectrum, for substance P (C5H12O). Which oxygen containing functional group is present in P? Ans: alcohol Topic: General 72. The six p-electrons in benzene are _____________ about the ring, which explains why all of the C-C bonds are the same length. Ans: delocalized Topic: General 73. A polar covalent bond is one in which electrons are _____________. Ans: not shared equally Topic: Functional Groups 74. Organic compounds are classified into chemical families on the basis of similarities in chemical properties; these similarities are primarily due to the presence of characteristic arrangements of atoms known as ________________. Ans: functional groups Topic: Functional Groups 75. Unsaturated hydrocarbons may be distinguished from saturated hydrocarbons by the presence of one or more _____________. Ans: Pi bonds Topic: Bonding, Solubility 76. Sodium chloride, which is quite soluble in water, is not very soluble in hexane. Why? Ans: Sodium chloride, which is an ionic substance, is soluble in a polar solvent such as water, but not in a non-polar solvent such as hexane. Topic: Isomers, Functional Groups 77. Draw all tertiary amine isomers of C6H15N. Ans: N N N N N N 59 Chapter 2 Topic: Isomers, Functional Groups 78. Draw all isomers of C6H14. Ans: Topic: Isomers, Functional Groups 79. Draw a structural formula for C8H18 , in which there are two quaternary carbons. Ans: Topic: Isomers, Functional Groups 80. Draw all isomers of C5H10O that are ketones. O O O Ans: Topic: Isomers, Functional Groups 81. Draw all isomers of C3H8O and classify each according to functional group OH Ans: C3H8O OH O primary alcohol secondary alcohol ether Topic: Isomers, Functional Groups 82. Draw all isomers of C6H12O that are aldehydes. Ans: O O O O O O O Topic: Isomers, Functional Groups 83. Draw all isomers of C6H12O that are aldehydes and contain at least one tertiary carbon Ans: O O O 60 O Chapter 2 Topic: IR Spectroscopy 84. The IR absorption frequencies of the C-H bond in alkanes, alkenes and alkynes are measurably different. Briefly explain why. Ans: IR absorption frequency depends on bond strength; the bond strength of C-H bonds in alkanes, alkenes and alkynes is different because different atomic orbitals (hybridized) of carbon are involved in the bond: the C-H bond in alkanes is described as (sp3-s), that in alkenes is (sp2-s) and in alkynes, it is (sp-s). The relative % s v. % p character of the hybrid orbitals of carbon would indicate different bond lengths /bond strengths for alkanes, alkenes and alkynes, with the bond length / bond strength being the longest/weakest respectively. This results in different IR absorption frequencies. Topic: Molecular Geometry, Dipole Moment 85. Carbon dioxide is non- polar, despite the fact that oxygen is much more electronegative than carbon. Briefly explain why, using relevant diagrams as appropriate to illustrate your Ans:wer. Ans: The overall dipole moment of a polyatomic molecule depends on two factors: the polarity of various bonds and molecular geometry, since dipole forces have both magnitude and direction. In some molecules containing bonds of identical polarity, the molecular geometry may result in a net cancellation of the overall dipole forces. This is what happens in carbon dioxide: although there are two polar C-O bonds, because of the linear geometry of the molecule, the net dipole is zero. .. .. : O C O: Topic: Intermolecular Forces 86. Ethanol, C2H5OH, and propane, C3H8, have approximately the same molar mass, yet, ethanol has a much higher boiling point. Briefly explain why. Ans: Strong hydrogen bonding between molecules of ethanol leads to elevation in boiling point. No hydrogen bonding is possible between molecules of propane, resulting in a lower boiling point compared with ethanol. Topic: Intermolecular Forces 87. Ethanol, C2H5OH, and dimethyl ether, CH3OCH3, have the same molar mass, yet, ethanol has a much higher boiling point. Briefly explain why. Ans: Strong hydrogen bonding between molecules of ethanol leads to elevation in boiling point. No hydrogen bonding is possible between molecules of dimethyl ether, resulting in a lower boiling point compared with ethanol. 61 Chapter 2 Topic: IR Spectroscopy 88. IR absorption signals of alcohols are typically broad. However, IR spectra of gaseous samples show sharp peaks. Briefly explain why. Ans: Broad signals of alcohols are due to hydrogen bonding associated with the O-H group. In gaseous samples, no hydrogen bonding is possible, and the signal becomes sharp. 62 Chapter 3 MULTIPLE CHOICE QUESTIONS Topic: Acid-Base Definitions 1. According to the Lewis definition, a base is a(n): A) Proton donor. B) Electron pair donor. C) Hydroxide ion donor. D) Hydrogen ion donor. E) Electron pair acceptor. Ans: B Topic: Acid-Base Definitions 2. Which of the following is not both a Bronsted-Lowry acid and a Bronsted-Lowry base? A) HSO4− B) H2PO4− C) HCO3− D) OH− E) SH− Ans: D Topic: Acid-Base Definitions 3. Which of the following is not a conjugate acid - conjugate base pair (in that order)? A) H3PO4, H2PO4− B) HBF4, BF4− C) CH3CH2OH, CH3CH2O− D) H3O+, H2O E) HPO4−, H2PO4− Ans: E Topic: Acid-Base Definitions 4. The conjugate base of sulfuric acid is: A) H3SO4+ B) SO3 C) HSO4− D) H2SO3 E) HSO3− Ans: C 63 Chapter 3 Topic: Acid-Base Definitions 5. Consider the equilibrium PO43− + H2O ⇄ ΗPΟ42− + ΟΗ− Which are the Bronsted-Lowry bases? A) PO43− and HPO42− B) PO43− and OH− C) PO43− and H2O D) H2O and OH− E) H2O and HPO42− Ans: B Topic: Acid-Base Definitions 6. Which of these is not a true statement? A) All Lewis bases are also Bronsted-Lowry bases. B) All Lewis acids contain hydrogen. C) All Bronsted-Lowry acids contain hydrogen. D) All Lewis acids are electron deficient. E) According to the Bronsted-Lowry theory, water is both an acid and a base. Ans: B Topic: Acid-Base Definitions 7. For the equilibrium CH3NH3+ + H2O ⇄ CH3NH3+ + H3O+ the two substances which both are acids are: A) H2O and H3O+ B) CH3NH3+ and H2O C) CH3NH3+ and CH3NH2 D) CH3NH3+ and H3O+ E) CH3NH2 and H2O Ans: D 64 Chapter 3 Topic: Acid-Base Definitions 8. Which of the following is not a Lewis base? A) NH3 B) H− C) BF3 D) H2O E) H3C− Ans: C Topic: Acid-Base Definitions 9. Which of the following is not a Bronsted-Lowry acid? A) H2O B) (CH3)3N C) NH4+ D) CH3CO2H E) HC≡CH Ans: E Topic: Acid-Base Definitions 10. The reaction between which combination of substances below cannot be classified as a Bronsted-Lowry acid-base reaction? A) CH3Li + C2H5OH B) H2SO4 + CH3CO2Na C) BF3 + NH3 D) H3O+ + CH3NHE) two of the above Ans: C Topic: Acid-Base Definitions 11. A) B) C) D) E) Which of these is not a Lewis acid? AlCl3 H3O+ FeCl3 SO3 C4H10 Ans: E 65 Chapter 3 Topic: Acid-Base Definitions 12. This species is a carbon-based Lewis acid: A) CH4 B) HCCl3 C) CH3+ D) :CH3− E) ·CH3 Ans: C Topic: Acid-Base Definitions 13. What is the conjugate base of ethanol? A) CH3CH2O− B) CH3CH2− C) CH3CH2OH2+ D) CH3CH3 E) CH3OCH3 Ans: A Topic: Acid-Base Strength 14. Which of the acids below would have the strongest conjugate base? A) CH3CH2OH pKa = 18 B) CH3CO2H pKa = 4.75 C) ClCH2CO2H pKa = 2.81 D) Cl2CHCO2H pKa = 1.29 E) Cl3CCO2H pKa = 0.66 Ans: A Topic: Acid-Base Definitions 15. Which of the following is a Lewis acid? A) H3O+ B) BF3 C) NF3 D) OH− E) N≡N Ans: B 66 Chapter 3 Topic: Acid-Base Reactions 16. Adding sodium hydride to ethanol would produce: D) CH3CH2Na + NaOH A) CH3CH2OCH2CH3 + H2 B) CH3CH2OCH2CH3 + NaOH E) CH3CH3 + NaOH C) CH3CH2ONa + H2 D)CH3CH2Na + NaOH E) CH3CH3 + NaOH Ans: C Topic: Acid-Base Reactions 17. Adding sodium amide (NaNH2) to 1-butyne (CH3CH2C≡CH) would produce: A) CH3CH2C≡CNa + NH3 B) CH3CH2C≡C-C≡CH2CH3 + NaH + NH3 C) CH3CH2C≡CNH2 + NaH D) NaCH2CH2C≡CH + NH3 E) CH3CH(Na)C≡CH + NH3 Ans: A Topic: Acid-Base Reactions 18. Which acid-base reaction would not take place as written? A) CH3Li + CH3CH2OH ⎯⎯⎯⎯→ CH4 + CH3CH2OLi B) HC≡CH + NaOH ⎯⎯⎯⎯→ HC≡CNa + H2O C) HC≡CNa + H2O ⎯⎯⎯⎯→ HC≡CH + NaOH D) CH3OH + NaH ⎯⎯⎯⎯→ CH3ONa + H2 E) CH3CO2H + CH3ONa ⎯⎯⎯⎯→ CH3CO2Na + CH3OH Ans: E Topic: Acid-Base Reactions 19. Which acid-base reaction would not take place as written? A) CH3Li + CH3CH2CH2CH2NH2 ⎯⎯⎯⎯→ CH4 + CH3CH2CH2CH2NHLi B) CH3C≡CH + NaOCH3 ⎯⎯⎯⎯→ HC≡CNa + CH3OH C) HC≡CNa + H2O ⎯⎯⎯⎯→ HC≡CH + NaOH D) CH3OH + NaNH2 ⎯⎯⎯⎯→ CH3ONa + NH3 E) CH3CO2H + CH3ONa ⎯⎯⎯⎯→ CH3CO2Na + CH3OH Ans: B 67 Chapter 3 Topic: Acid-Base Reactions 20. Which acid-base reaction would not take place as written? A) CH3Li + CH3CH2OH ⎯⎯⎯⎯→ CH4 + CH3CH2OLi B) H2C=CH2 + NaOH ⎯⎯⎯⎯→ H2C=CHNa + H2O C) CH3C≡CNa + H2O ⎯⎯⎯⎯→ CH3C≡CH + NaOH D) (CH3)2CHOH + NaH ⎯⎯⎯⎯→ (CH3)2CHONa + H2 E) CH3CO2H + CH3ONa ⎯⎯⎯⎯→ CH3CO2Na + CH3OH Ans: B Topic: Acid-Base Reactions 21. The amide ion, NH2−, is a base which can be used only in which of the solvents shown below: A) CH3OH B) CH3CH2OH C) H2O D) D2O E) Liquid NH3 Ans: E Topic: Acid-Base Reactions 22. Acetic acid dissociates most completely in: A) CCl4 B) Cl2C=CCl2 C) H2O D) (CH3CH2)2O E) the gas phase. Ans: C Topic: Acid-base definitions, Acid-Base Reactions 23. Which pair of species are both bases in the following reaction? HCN and H2O ⇄ A) B) C) D) E) H3O+ and CN− H2O and CN− H3O+ and H2O HCN and H3O+ HCN and CN− H3O+ and CN− Ans: A 68 Chapter 3 Topic: Acid-Base Reactions 24. What compounds are produced when sodium nitrate is added to a mixture of water and ethanol? A) HNO3 + NaOH B) HNO3 + CH3CH2ONa C) NaOH + CH3CH2ONa D) CH3CH2OCH2CH3 + NaOH E) No reaction occurs. Ans: E Topic: Acid-Base Reactions 25. Which reaction of these potential acids and bases does not occur to any appreciable degree due to an unfavorable equilibrium? A) NaOH (aq) + CH3CH2CH2CO2H B) CH3CH2ONa in ethanol + ethene C) CH3Li in hexane + ethyne D) NaNH2 in liq. NH3 + ethanol E) NaC2H3O2 (aq) + HI Ans: B Topic: Acid-Base Reactions 26. Which reaction of these potential acids and bases does not occur to any appreciable degree due to an unfavorable equilibrium? A) NaNH2 + CH3CH2CH2CH2CH2CH3 B) CH3CH2CO2Na + HI C) CH3Li in hexane + ethyne D) NaH + methanol E) Two of the above will not occur Ans: A Topic: Acid-Base Reactions 27. Which reaction of these potential acids and bases does not occur to any appreciable degree due to an unfavorable equilibrium? A) NaNH2 + CH3CH2CH2CH2CH2OH B) CH3CH2CO2H + NaCl C) NaHCO3 + CH3CH2CO2H D) NaH + CH3CH2CH2CH2CH2NH2 E) all of the above will occur due to a favorable equilibrium Ans: E 69 Chapter 3 Topic: Acid-Base Reactions 28. Which combination of reagents is the least effective in generating sodium ethoxide, CH3CH2ONa? A) CH3CH2OH + NaH B) CH3CH2OH + NaNH2 C) CH3CH2OH + NaOH D) CH3CH2OH + CH3Li E) CH3CH2OH + HC≡CNa Ans: C Topic: Acid-Base Reactions 29. Which combination of reagents is effective in generating sodium ethoxide, CH3CH2ONa? A) CH3CH2OH + KH B) CH3CH2OH + NaNH2 C) CH3CH2OH + Na D) Two of the above E) All of the above Ans: E Topic: Acid-Base Reactions 30. Which combination of reagents is effective in generating sodium propynide, CH3C≡CNa? A) CH3C≡CH + KH B) CH3C≡CH + (CH3)2CHONa C) CH3C≡CH + C2H5Li D) Two of the above E) All of the above Ans: B Topic: Acid-Base Reactions, base strength 31. In the reaction, Na+NH2− + CH3OH ⎯⎯⎯⎯→ CH3O−Na+ + NH3, the stronger base is: A) NaNH2 B) CH3OH C) CH3ONa D) NH3 E) This is not an acid-base reaction. Ans: A 70 Chapter 3 Topic: Acid-Base Reactions, isotope labeling 32. Which sequence is the best one to use to prepare CH3C≡CD? D2O A) CH C CH NaH 3 B) CH C CH 3 C) CH3C CH NaOH D2O CH3ONa D2O D) CH C CH DOH 3 E) None of these will be successful. Ans: A Topic: Acid-Base Reactions 33. Adding sodium hydride, NaH, to water produces: A) H2 and NaOH(aq) B) H-(aq) + Na+(aq) C) H3O+(aq) + Na+(aq) D) H3O−(aq) + Na+(aq) E) Na2O + H2 Ans: A Topic: Acid-Base Reactions 34. Adding methyllithium , CH3Li, to ethanol produces: A) CH3CH2Li + CH3OH B) CH3CH2OLi + CH4 C) CH3CH2OCH3 + LiH D) All of the above E) No reaction takes place Ans: A Topic: Acid-Base Reactions, isotope labeling 35. Which reaction will yield CH3CH2-D? A) CH3CH3 + D2O B) CH3CH2Li + D2O C) CH3CH2OLi + D2O D) CH3CH2OH + D2O E) More than one of these Ans: B 71 Chapter 3 Topic: Acid-Base Reactions, isotope labeling 36. A product of the reaction, CH3CH2Li + D2O ⎯⎯⎯⎯→ is A) CH3CH2OD B) CH3CH2CH2CH3 C) CH2=CH2 D) CH3CH2D E) CH3CH2OCH2CH3 Ans: D Topic: Relative acid strength 37. The compounds ethane, ethene, and ethyne exhibit this order of increasing acidity: A) Ethyne < ethene < ethane B) Ethene < ethyne < ethane C) Ethane < ethyne < ethene D) Ethane < ethene < ethyne E) Ethene < ethane < ethyne Ans: D Topic: Relative acid/base strength 38. Which is an incorrect statement? A) RSH compounds are stronger acids than ROH compounds. B) PH3 is a weaker base than NH3. C) NH2− is a stronger base than OH−. D) OH− is a stronger base than OR−. E) H− is a stronger base than OR−. Ans: D Topic: Relative acid/base strength 39. The correct sequence of the ions shown, in order of increasing basicity, is: A) CH3CH2:− < CH2=CH:− < HC≡C:− B) CH3CH2:− < HC≡C:− < CH2=CH:− C) HC≡C:− < CH3CH2:− < CH2=CH:− D) CH2=CH:− < HC≡C:− < CH3CH2:− E) HC≡C:− < CH2=CH:− < CH3CH2:− Ans: E 72 Chapter 3 Topic: Solvent effects 40. Which is a protic solvent? A) CCl4 B) HCCl3 C) CH3OH D) CH3(CH2)4CH3 E) CH3CH2OCH2CH3 Ans: C Topic: Solvent effects 41. Which might be used as protic solvent? O A) O B) C) H2N O N D) O O E) Ans: B Topic: Solvent effects 42. Which of the following classes of substances cannot be used as protic solvents? A) esters B) aldehydes C) ketones D) carboxylic acids E) two of the above Ans: D 73 Chapter 3 Topic: Acid constants 43. If a 0.01 M solution of a weak acid has a pH of 4.0, the pKa of the acid is: A) 10.0 B) 8.0 C) 6.0 D) 4.0 E) 2.0 Ans: C Topic: General 44. Which one of the following is a true statement? A) The stronger the acid, the larger is its pKa. B) The conjugate base of a strong acid is a strong base. C) Acid-base reactions always favor the formation of the stronger acid and the stronger base. D) Strong acids can have negative pKa values. E) Hydrogen need not be present in the molecular formula of a Bronsted-Lowry acid. Ans: D Topic: Relative acid/base strengths 45. The basic species are arranged in decreasing order of basicity in the sequence: A) F− > OCH3− > NH2− > CH3CH2− B) OCH3− > CH3CH2− > NH2− > F− C) CH3CH2− > NH2− > OCH3− > F− D) NH2− > CH3CH2− > F− > OCH3− E) NH2− > OCH3− > CH3CH2− > F− Ans: C Topic: pKa calculations 46. A particular acid has Ka = 2.0 x 10-5 (in aqueous solution). The evaluation of which of these expressions gives the value for pKa? A) 10-14/2.0 x 10-5 B) 10-14(2.0 x 10-5) C) 5 – log 2.0 D) -5 + log 2.0 E) 2.0 x 10-5/10-14 Ans: C 74 Chapter 3 Topic: Solvent effects 47. As a consequence of the "leveling effect," the strongest acid which can exist in appreciable concentration in aqueous solution is: A) H3O+ B) H2SO4 C) HClO4 D) HCl E) HNO3 Ans: A Topic: Relative acid/base strengths 48. Based on the position of the central atom in the periodic chart, we predict that the strongest acid of the following is: A) H2O B) H2S C) H2Se D) H2Te Ans: D Topic: Acid dissociation, thermodynamic calculations 49. An acid, HA, has the following thermodynamic values for its dissociation in water at 27º C: ΔH = -8.0 kJ mol-1; ΔS = -70 kJ K-1mol-1. The ΔG for the process is: A) +29 kJ mol-1 B) +13 kJ mol-1 C) -6.1 kJ mol-1 D) -13 kJ mol-1 E) -29 kJ mol-1 Ans: B Topic: Relative acid/base strengths, solvent effects 50. Which of these bases is the strongest one which can be used (and retains its basic character) in aqueous solution? A) OCH3− B) F− C) OH− D) C2H3O2− E) HSO4− Ans: C 75 Chapter 3 Topic: Acidity constant- thermodynamic principles 51. The acidity constant, Ka, differs from the equilibrium constant, Keq, for the dissociation of the same acid in water at the same temperature and concentration in what way? A) Ka can be determined experimentally with less accuracy than Keq. B) The two terms are identical numerically. C) Ka is used for strong acids only; Keq for weak acids. D) Ka is the reciprocal of Keq. E) Keq = Ka/[H2O]. Ans: E Topic: Acids/bases-general principles 52. Which of the following is an untrue statement? A) The % dissociation of a weak acid increases with increasing dilution of the acid solution. B) The stronger an acid, the weaker its conjugate base. C) The larger the value of Ka for an acid, the smaller the value of its pKa. D) Comparison of the acidity of strong acids in solution requires the use of a solvent less basic than water. E) The stronger the acid, the more positive the value of ΔGº for the dissociation. Ans: E Topic: Acid-base reactions 53. When proton transfer reactions reach equilibrium, there have been formed: A) the weaker acid and the weaker base. B) the weaker acid and the stronger base. C) the stronger acid and the weaker base. D) the stronger acid and the stronger base. E) All proton transfers go to completion; they are not equilibrium processes. Ans: A Topic: Relative acid-base strengths 54. For the simple hydrides, MHn, pKa values decrease in the order: A) CH4 > NH3 > H2O > H2S > HBr B) HBr > H2S > H2O > NH3 > CH4 C) HBr > H2O > NH3 > H2S > CH4 D) NH3 > H2S > CH4 > H2O > HBr E) H2S > H2O > HBr > NH3 > CH4 Ans: A 76 Chapter 3 Topic: Relative acid-base strengths, solvent effects 55. The compound aniline, C6H5NH2, has weakly basic properties in aqueous solution. In this other solvent, aniline would behave as a strong base. A) CH3OH B) CH3CH2OH C) CF3CO2H D) Liquid NH3 E) CH3(CH2)4CH3 Ans: C Topic: Relative acid-base strengths 56. Which of the following organic compounds is the strongest acid? A) C6H12 pKa = 52 B) CH3CH3 pKa = 50 C) CH3CH2OH pKa = 18 D) CH3CO2H pKa = 5 E) CF3CO2H pKa = 0 Ans: E Topic: Relative acid-base strengths 57. Which is the strongest acid? A) CH3CH2OH B) CH3CO2H C) HC≡CH D) CH2=CH2 E) CH3CH3 Ans: B Topic: Relative acid-base strengths 58. A) B) C) D) E) Which is the strongest acid? CH2ClCH2CH2CH2CH2CO2H CH3CHBrCH2CH2CH2CO2H CH3CH2CH2CBr2CH2CO2H CH3CH2CH2CHFCH2CO2H CH3CH2CH2CF2CH2CO2H Ans: E 77 Chapter 3 Topic: Relative acid-base strengths 59. A) B) C) D) E) Which is the strongest acid? CH3CH2CH2CH2CHFCO2H CH3CHBrCH2CH2CH2CO2H CH3CH2CH2CHClCH2CO2H CH3CH2CH2CHFCH2CO2H CH3CH2CH2CHICH2CO2H Ans: A Topic: Relative acid-base strengths 60. A) B) C) D) E) Which is the weakest acid? CH3CH2CH2CH2CHFCO2H CH3CHCH2CH2CH2CH2OH CH3CH2CH2CH2CH2SO3H CH3CH2CH2CH2CH=CH2 CH3CH2CH2CH2NH2 Ans: A Topic: Relative acid-base strengths 61. A) B) C) D) E) Which of the following substances has a hydrogen atom with pKa ≈25? CH3CH2CH2CH2CO2H CH3CHCH2C≡CCH3 CH3CH2CH2C≡CH CH3CH2CH2CH2CH=CH2 CH3CH2CH2CH2NH2 Ans: C 78 Chapter 3 Topic: Relative acid-base strengths 62. Hydrogen atom(s) from which position(s) is (are) most likely to be abstracted when the following substance is treated with NaH? 9 10 8 1 6 7 A) B) C) D) E) 4 5 2 3 1 1, 5, 6 1, 2 3, 4, 7, 8, 9, 10 Hydrogens from all of the positions are equally likely to be abstracted by NaH. Ans: A Topic: Relative acid-base strengths 63. Which of the following correctly lists the compounds in order of decreasing acidity? A) H2O > HC≡CH > NH3 > CH3CH3 B) HC≡CH > H2O > NH3 > CH3CH3 C) CH3CH3 > HC≡CH > NH3 > H2O D) CH3CH3 > HC≡CH > H2O > NH3 E) H2O > NH3 > HC≡CH > CH3CH3 Ans: A Topic: Relative acid-base strengths 64. Select the strongest base. A) OH− B) RC≡C− C) NH2− D) CH2=CH− E) CH3CH2− Ans: E 79 Chapter 3 Topic: Relative acid-base strengths 65. A group of acids arranged in order of decreasing acidity is: HNO3 > CH3COOH > C6H5OH > H2O > HC≡CH What is the arrangement of the conjugate bases of these compounds in decreasing order of basicity? A) NO3− > CH3COO− > C6H5O− > OH− > HC≡C− B) CH3COO− > C6H5O− > NO3− > OH− > HC≡C− C) C6H5O− > NO3− > HC≡C− > OH− > CH3COO− D) HC≡C− > OH− > C6H5O− > CH3COO− > NO3− E) No prediction of relative base strength is possible. Ans: D Topic: Relative acid-base strengths 66. What prediction can be made of the relative strengths of the conjugate bases of: H2S, HCl, SiH4, PH3? A) PH2− > SiH3− > HS− > Cl− B) SiH3− > PH2− > HS− > Cl− C) Cl− > HS− > PH2− > SiH3− D) HS− > Cl− > SiH3− > PH2− E) Cl− > PH2− > SiH3− > HS− Ans: B Topic: Acids/bases- general 67. Which of these species is not amphoteric? A) HC≡C− B) HS− C) NH3 D) CH3− E) HPO4− Αns: D 80 Chapter 3 Topic: Acids/bases- general 68. Which of these phosphorus-based acids is dibasic? O A) P HO OH OH O B) HO P OH H O C) H P H OH O D) HO P O O OH O O E) HO P P P OH OH OH OH OH Ans: B Topic: Acids/bases- general 69. Why cannot one determine the relative acid strengths of HClO4 and HNO3 using aqueous solutions of these acids? A) The acids are insufficiently soluble for the measurements. B) A more basic solvent than H2O must be used. C) H2O is too basic a solvent for the distinction to be made. D) These oxidizing acids cause redox reactions to occur. E) Actually, the acid strengths can be determined using aqueous solutions. Ans: C Topic: Acids/bases- general 70. Which of these is not a diprotic acid? A) H2S B) H2SO4 C) H2O D) (COOH)2 E) H2PO4Ans: C 81 Chapter 3 Topic: Acids/bases- thermodynamic principles 71. Which set contains non-equivalent members? A) Enthalpy and heat content B) Endothermic reaction and +ΔH C) Exothermic reaction and -ΔH D) Kinetic energy and energy of motion E) High energy and high stability Ans: E SHORT-ANSWER QUESTIONS: Topic: General Reactivity 72. Addition reactions are characteristic of compounds with ______________. Ans: multiple bonds Topic: Reaction Types 73. The four basic types of reactions are: ________________. Ans: substitution, addition, elimination, rearrangement Topic: Reaction Mechanisms 74. The process of bond-breaking where each fragment takes away one of the electrons from the bond is called ____________. Ans: homolysis Topic: Reaction Mechanisms 75. Heterolytic bond-breaking produces __________. Ans: charged fragments/ions Topic: Acids and Bases 76. According to Bronsted-Lowry theory, an acid is a substance that can ____________. Ans: donate a proton Topic: Acids and Bases 77. According to Lewis theory, a base is a substance that can _________. Ans: donate a lone pair of electrons 82 Chapter 3 Topic: Acids and Bases 78. The molecule or ion that is formed when an acid loses its proton is called the ______________. Ans: conjugate base Topic: Nucleophiles and Electrophiles 79. Reagents that seek to react with a proton or some other electron-deficient center are called ____________. Ans: nucleophiles Topic: Acids and Bases 80. A substance that can donate a lone pair of electrons is a ____________ according to ____________ theory. Ans: base; Lewis Topic: Curved Arrow Notation 81. When drawing mechanisms, chemists generally use curved arrows. The curved arrow begins with ______________ and points toward ______________. Ans: a lone pair or covalent bond; a site of electron deficiency Topic: Acids and Bases 82. Why do water-insoluble carboxylic acids dissolve in aqueous sodium hydroxide? Ans: Because they are converted to water-soluble salts. Topic: Relative Acidity 83. Bond polarization that takes place through space and through the bonds of the molecule is called the _____________. Ans: inductive effect Topic: Energy 84. What are the two fundamental types of energy? Ans: potential energy and kinetic energy Topic: Types of Solvents 85. Define a protic solvent. Ans: one that has a hydrogen atom attached to a strongly electronegative element such as oxygen 83 Chapter 3 Topic: Relative acid strength 86. Briefly, but clearly, explain why the –OH hydrogen in acetic acid (CH3CO2H) is more acidic than in ethanol (C2H5OH). Ans: The greater acidity of the –OH hydrogen in acetic acid is due primarily to two factors: resonance and inductive effects. In acetic acid, the presence of the neighboring carbonyl group has an electron-withdrawing inductive effect on the –OH hydrogen, increasing its acidity relative to ethanol, in which there is no carbonyl group. Also, comparison of the respective conjugate bases shows that, unlike the ethoxide ion, the acetate ion is stabilized by resonance. This too, is reflected in the greater acid strength of the corresponding acid species. O O H O (- H+) O Inductive effect: electron withdrawing O O H O resonance stabilized anion (- H+) O 84 Chapter 3 Topic: Relative acid strength, isotope labeling 87. Isotope labeling is an important tool in the study of reaction mechanisms. How will you selectively deuterate the specified hydrogen atom, indicated by an arrow, in the following compound? Use equations to clarify your answer and briefly explain your rationale. H Ans: The specified hydrogen is attached to an sp-hybridized carbon and is thus more acidic than all the other hydrogens in the molecule. By using an appropriate strong base, such as NaH or NaNH2, the acetylenic hydrogen is selectively removed; adding D2O then replaces the lost hydrogen atom with a deuterium atom. H D i) NaH or NaNH2 ii) D2O Topic: Acid-base reactions 88. Write an equation to show the reaction between ethanol, C2H5OH and methyllithium, CH3Li. Draw all non-bonding electrons and show electron flow with curved arrows. Ans: .. H + O .. .. + O : Li .. : CH3 Li+ + CH4 Topic: Acid-base reactions, solvent selection 89. You are planning to carry out a reaction between propyne, CH3C≡CH and sodium amide, NaNH2. You also need to choose an appropriate solvent for carrying out the reaction. Would ethanol be suitable for this purpose? Explain your rationale clearly. Ans: No, ethanol would be unsuitable for carrying out the reaction between propyne and methyllithium. The pKa of ethanol is ~16, and sodium amide is strong enough a base to readily abstract a proton from the solvent ( pKa of NH3 is ~38); in doing so, it becomes deactivated and is no longer available to react with propyne (pKa ~25). Typically, the selected solvent should be chemically inert toward all substances used in the reaction, so that it does not interfere with the desired reaction. 85 Chapter 3 Topic: Acid-base reactions, solvent selection 90. You are planning to purify an impure sample of benzoic acid, known to be contaminated with naphthalene. Propose a strategy for purifying this sample, making use of acid-base principles, using equations to further clarify your answer. Ans: Benzoic acid reacts with aqueous NaOH to form a water soluble salt, while naphthalene, which is not soluble in water to any appreciable extent, does not react with NaOH. So, upon shaking the impure sample with NaOH (aq), the naphthalene remains as a solid, while the benzoic acid dissolves in the aqueous medium as sodium benzoate. After filtration, HCl is added to the filtrate to regenerate benzoic acid, which precipitates as almost pure crystals. Cooling maximizes the yield of the purified product, after which pure crystals can be obtained by filtration. Alternatively, before beginning the reaction with aqueous NaOH, the impure sample is first dissolved in diethyl ether (benzoic acid and naphthalene are both soluble in ether) and placed in a separatory funnel. After shaking thoroughly with aqueous NaOH, the aqueous layer (which now contains sodium benzoate) is collected. The rest of the procedure is as described earlier. O O OH NaOH water insoluble O OH O ONa water soluble NaOH X No reaction water insoluble 86 HCl OH water insoluble PURE Chapter 4 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. A) B) C) D) E) The IUPAC name for 6-Ethyl-3,4-dimethylheptane 2-Ethyl-4,5-dimethylheptane 3,4,6-Trimethyloctane 3,5,6-Trimethyloctane 2-(1-Methylpropyl)-4-methylhexane Ans: C is: Topic: Nomenclature 2. A) B) C) D) E) An IUPAC name for 5-Methyl-4-(1-methylpropyl)hexane 2-Methyl-3-(1-methylpropyl)hexane 2-Methyl-3-(2-methylpropyl)hexane 3-Methyl-4-(1-methylethyl)heptane 5-Methyl-4-(1-methylethyl)heptane Ans: D is: Topic: Nomenclature 3. A correct IUPAC name for the following compound is: A) B) C) D) E) 2,5-Dimethyl-3-propylheptane 3,6-Dimethyl-5-propylheptane 6-Methyl-4-(1-methylethyl)octane 2-Methyl-3-(2-methylbutyl)hexane 3-Methyl-5-(1-methylethyl)octane Ans: E 87 Chapter 4 Topic: Nomenclature 4. A correct IUPAC name for the following compound is: OH A) B) C) D) E) Ans: Cl 4-propyl-5-chloro-3-heptanol 4-propyl-3-chloro-5-heptanol 4-(1-chloropropyl)-3-heptanol 5-chloro-4-propyl-3-heptanol 3-hydroxy-4-propyl-5-chloroheptane D Topic: Nomenclature 5. A) B) C) D) E) Which of the following pairs of compounds represent pairs of constitutional isomers? 2-Methylbutane and pentane 2-Chlorohexane and 3-chlorohexane sec-Butyl bromide and tert-butyl bromide Propyl chloride and isopropyl chloride All of the above Ans: E 88 Chapter 4 Topic: Nomenclature 6. Which of the following is bicyclo[3.2.2]nonane? I II IV A) B) C) D) E) III V I II III IV V Ans: C Topic: Nomenclature 7. Select the systematic name for A) B) C) D) E) Cl H H Cl cis-1,3-Dichlorocyclopentane trans-1,4-Dichlorocyclopentane cis-1,2-Dichlorocyclopentane trans-1,3-Dichlorocyclopentane 1,1-Dichlorocyclopentane Ans: D 89 Chapter 4 Topic: Nomenclature 8. Which compound is a bicycloheptane? I II IV A) B) C) D) E) III V I II III IV V Ans: D Topic: Nomenclature 9. A) B) C) D) E) Which isomer of C5H10 would you expect to have the smallest heat of combustion? Cyclopentane Methylcyclobutane 1,1-Dimethylcyclopropane cis-1,2-Dimethylcyclopropane trans-1,2-Dimethylcyclopropane Ans: A Topic: Nomenclature 10. Which is the correct name for the compound shown below? A) B) C) D) E) Bicyclo[2.2.0]hexane Bicyclo[2.2.0]butane Bicyclo[2.2.2]hexane Bicyclo[2.2.1]hexane Disquarane Ans: A 90 Chapter 4 Topic: Nomenclature 11. What is the name of this compound? A) B) C) D) E) Bicyclo[2.2.2]octane Bicyclo[3.2.1]octane Bicyclo[4.1.1]octane Bicyclo[4.2.0]octane Bicyclo[3.3.0]octane Ans: D Topic: Nomenclature 12. What is the common name for this compound? Br A) B) C) D) E) Isobutyl bromide tert-Butyl bromide Butyl bromide sec-Butyl bromide Bromo-sec-butane Ans: A Topic: Nomenclature 13. A correct IUPAC name for the following compound is: Br A) B) C) D) E) Ans: 3,6,7-trimethyl-4-bromo-1-octene 4-bromo-3-methyl-6-isopropyl-1-heptene 4-bromo-3,6,7-trimethyl-1-octene 4-bromo-6-isopropyl-3-methyl-1-heptene 4-bromo-6-isopropyl-3,6-dimethyl-1-hexene C 91 Chapter 4 Topic: Nomenclature 14. A correct name for the following compound is: A) B) C) D) E) 2-Methylbicyclo[4.3.0]nonane 1-Methylbicyclo[4.3.1]nonane 7-Methylbicyclo[4.3.0]nonane 2-Methylbicyclo[4.3.1]nonane 1-Methylbicyclo[4.3.0]nonane Ans: A Topic: Nomenclature Use the following to answer questions 15-17: I II IV 15. A) B) C) D) E) III V Which of the above is bicyclo[3.3.1]nonane? I II III IV V Ans: D Topic: Nomenclature 16. A) B) C) D) E) Which of the above is bicyclo[5.2.0]nonane? I II III IV V Ans: E 92 Chapter 4 Topic: Nomenclature 17. A) B) C) D) E) Which of the above is bicyclo[4.3.0]nonane? I II III IV V Ans: A Topic: Nomenclature Use the following to answer questions 18-19: Br H H Br Br H H I Br Br H Br H II III Topic: Nomenclature 18. A) B) C) D) E) trans-1,2-Dibromocyclohexane is represented by structure(s): I II III II and III I and II Ans: D Topic: Nomenclature 19. A) B) C) D) E) cis-1,2-Dibromocyclohexane is represented by structure(s): I II III II and III I and II Ans: A 93 Chapter 4 Topic: Nomenclature 20. cis-1,3-Dibromocyclohexane is represented by structure(s): Br H Br H H H I A) B) C) D) E) H Br Br Br Br II III I II III II and III I and II Ans: A Topic: Nomenclature 21. A) B) C) D) E) CH3CHCH2− CH2CH3 is: An IUPAC name for the group Isopentyl Isoamyl sec-Butylmethyl 2-Methylbutyl 2-Ethylpropyl Ans: D Topic: Nomenclature 22. A) B) C) D) E) H The neopentyl group has the alternative name: 1,1-Dimethylpropyl 1,2-Dimethylpropyl 2,2-Dimethylpropyl 1-Methylbutyl 2-Methylbutyl Ans: C 94 Chapter 4 Topic: Nomenclature 23. A) B) C) D) E) Br Cl is: The correct IUPAC name for 2-Bromo-4-chloro-4-isopropylpentane 4-Bromo-2-chloro-2-isopropylpentane 5-Bromo-3-chloro-2,3-dimethylhexane 2-Bromo-4-chloro-4,5-dimethylhexane 2-(2-Bromopropyl)-2-chloro-3-methylbutane Ans: C Topic: Nomenclature 24. Which of the following is a correct name which corresponds to the common name tertpentyl alcohol? A) 2,2-Dimethyl-1-propanol B) 2-Ethyl-2-propanol C) 2-Methyl-2-butanol D) 3-Methyl-1-butanol E) Methyl tert-butanol Ans: C Topic: Nomenclature 25. The correct IUPAC name for the following compound is: OH A) B) C) D) E) 1-Hydroxy-3-sec-butylcyclopentane 3-sec-Butyl-1-cyclopentanol 1-sec-Butyl-3-cyclopentanol 4-sec-Butyl-1-cyclopentanol 3-Isobutyl-1-cyclopentanol Ans: B 95 Chapter 4 Topic: Nomenclature 26. What is a correct name for the following compound? A) B) C) D) E) 3-Isobutyl-2-methylheptane 3-sec-Butyl-2-methyloctane 5-Isobutyl-6-methylheptane 2-Ethyl-3-isopropyloctane 4-Isopropyl-3-methylnonane Ans: E Topic: Nomenclature 27. What is the correct name of the following compound? Cl A) B) C) D) E) 1-Chlorobicyclo[4.1.1]octane 2-Chlorobicyclo[4.1.0]octane 2-Chlorobicyclo[4.1.1]octane 2-Chlorobicyclo[4.1.1]heptane 5-Chlorobicyclo[4.1.1]octane Ans: C Topic: Nomenclature 28. What is the correct IUPAC name for the following compound? HO A) B) C) D) E) 3-Hydroxymethylheptane 3-Hydroxymethylhexane 3-Methyloxyheptane 2-Ethyl-1-hexanol 2-Ethyl-1-heptanol Ans: D 96 Chapter 4 Topic: Nomenclature 29. Which of the following structures represents bicyclo[3.2.1]octane? I II IV A) B) C) D) E) III V I II III IV V Ans: E Topic: Nomenclature 30. A) B) C) D) E) Which of these is the common name for the 1,1-dimethylpropyl group? tert-Butyl tert-Pentyl Isopentyl Neopentyl sec-Pentyl Ans: B Topic: Nomenclature 31. Neglecting stereochemistry, which of these common group names is ambiguous, i.e., does not refer to one specific group? A) Butyl B) sec-Butyl C) tert-Pentyl D) Neopentyl E) sec-Pentyl Ans: E 97 Chapter 4 Topic: Nomenclature 32. What is the correct IUPAC name for the following compound? OH A) B) C) D) E) 5-Ethyl-3-methylhexanol 5-Ethyl-3-methyl-1-hexanol 2-Ethyl-4-methyl-6-hexanol 3,5-Dimethyl-7-heptanol 3,5-Dimethyl-1-heptanol Ans: E Topic: Nomenclature 33. Isopentyl is the common name for which alkyl group? A) CH3CH2CH2CH CH3 B) CH3CH2CHCH2 CH3 CH CHCH C) 3 2CH2 CH3 D) CH3CH2CH CH2CH3 E) CH3 CH3CCH2 CH3 Ans: C 98 Chapter 4 Topic: Nomenclature 34. A) B) C) D) E) An IUPAC name for 3-Isobutyl-2,4-dimethylhexane 3-sec-Butyl-2,5-dimethylhexane 4-sec-Butyl-2,5-dimethylhexane 4-Isopropyl-2,5-dimethylheptane 4-Isopropyl-3,6-dimethylheptane Ans: D is: Topic: Nomenclature 35. An IUPAC name for the following compound is: A) B) C) D) E) 4-Isobutyl-3,4-dimethylheptane 4-sec-Butyl-2,4-dimethylheptane 2,4,5-Trimethyl-4-propylheptane 3,4,6-Trimethyl-4-propylheptane 4-Isobutyl-4,5-dimethylheptane Ans: C Topic: Nomenclature 36. What is the correct IUPAC name for the following compound? HO A) B) C) D) E) 3-Hydroxymethyl-2-heptene 2-(1-methylethyl)-4-hexen-1-ol 5-(1-methylethyl)-2-hexen-6-ol 5-isopropyl-2,6-hexenol 2-(1-methylethyl)-4-hepten-1-ol Ans: B 99 Chapter 4 Topic: Nomenclature 37. What is the correct IUPAC name for the following compound? OH F A) B) C) D) E) 5-Ethyl-3-fluorohexanol 5-Ethyl-3-fluoro-1-hexanol 2-Ethyl-4-fluoro-6-hexanol 3-fluoro-5-methyl-7-heptanol 3-fluoro-5-methyl-1-heptanol Ans: E Topic: Nomenclature 38. A correct name for the following compound is: Cl A) B) C) D) E) 3-chloro-8-methylbicyclo[4.3.0]nonane 8-Methyl-3-chlorobicyclo[4.3.1]nonane 3-Methyl-7-chlorobicyclo[4.3.0]nonane 3-Methyl-7-chlorobicyclo[4.3.1]decane 3-chloro-8-methyl[4.3.0]bicyclononane Ans: A Topic: Nomenclature 39. A correct name for the following compound is: Br A) B) C) D) E) 4-bromo-3,8-dimethylbicyclo[5.2.2]nonane 3,8-dimethyl-4-bromo-bicyclo[5.2.0]nonane 4-bromo-3,8-dimethylbicyclo[5.2.1]decane 7-bromo-2,6-dimethylbicyclo[5.2.0]nonane 4-bromo-3,8-dimethylbicyclo[5.2.0]nonane Ans: E 100 Chapter 4 Topic: Conformational Analysis 40. The least stable conformation of butane is: H H3C H H3C H H H H CH3 CH3 H H H I H3C H H II III H A) B) C) D) E) CH3 H CH3 H CH3 H H CH3 H H H IV V CH3 H I II III IV V Ans: B Topic: Conformational Analysis 41. A) B) C) D) E) The preferred conformation of cis-3-tert-butyl-1-methylcyclohexane is the one in which: the tert-butyl group is axial and the methyl group is equatorial. the methyl group is axial and the tert-butyl group is equatorial. both groups are axial. both groups are equatorial. the molecule exists in a boat conformation. Ans: D 101 Chapter 4 Topic: Conformational Analysis 42. What structure represents the most stable conformation of cis-1,3-dimethylcyclohexane? CH3 H H H CH3 H3C H CH3 H H3C I H II III H H CH3 H3C CH3 H3C H H V IV A) B) C) D) E) CH3 I II III IV V Ans: B Topic: Ring Strain 43. Which cycloalkane has the largest heat of combustion per CH2 group? I A) B) C) D) E) IV I II III IV V Ans: A II III V 102 Chapter 4 Topic: Ring Strain 44. Which cycloalkane has the lowest heat of combustion per CH2 group? I II IV A) B) C) D) E) III V I II III IV V Ans: D Topic: Ring Strain 45. A) B) C) D) E) Which isomer would have the largest heat of combustion? Propylcyclopropane Ethylcyclobutane Methylcyclopentane Cyclohexane Since they are all isomers, all would have the same heat of combustion. Ans: A Topic: Ring Strain 46. A) B) C) D) E) Which is the most stable conformation of cyclohexane? Chair Twist Boat One-half chair Staggered Ans: A 103 Chapter 4 Topic: Ring Strain 47. A) B) C) D) E) Which cycloalkane has the greatest ring strain? Cyclopropane Cyclobutane Cyclopentane Cyclohexane Cycloheptane Ans: A Topic: Conformational Analysis 48. The most stable conformation of butane is: H H3C H H3C H H H H CH3 CH3 H H H I H3C H H II III H A) B) C) D) E) CH3 H CH3 H CH3 H CH3 H CH3 H H H H IV V I II III IV V Ans: C 104 Chapter 4 Topic: Conformational Analysis 49. The most stable conformation of 1,2-dibromoethane is: H Br H Br H H H H Br Br H H H I H Br H H II III H A) B) C) D) E) Br Br H Br H H Br H H H IV V Br H I II III IV V Ans: C 105 Chapter 4 Topic: Conformational Analysis 50. The most stable conformation of 2,3-dibromobutane, viewed through the C-2—C-3 bond : CH3 Br H Br H H H H Br Br H3C H3C CH3 I H3C Br CH3 H II III Br Br A) B) C) D) E) Br H3C H H Br H3C H H3C H Br CH3 IV V I II III IV V Ans: C 106 Chapter 4 Topic: Conformational Analysis 51. The most stable conformation of 3-bromo-2-methylpentane, viewed through the C-3—C-4 bond (i.e., C-3 in the front, C-4 in the back): CH3 Br H H Br H H CH3 CH(CH3)2 H H H CH(CH3)2 I H H CH3 CH(CH3)2 II III CH3 H Br CH(CH3)2 H A) B) C) D) E) Br H Br H CH3 CH3 H CH2CH3 IV V I II III IV V Ans: A 107 Chapter 4 Topic: Conformational Analysis 52. The most stable conformation of 3-bromo-2-methylpentane, viewed through the C-2—C-3 bond (i.e., C-2 in the front, C-3 in the back): H H CH3 Br CH3 H Br H CH3 CH2CH3 H H3C CH3 I H H CH3 CH(CH3)2 II III CH3 CH3 Br CH2CH3 H A) B) C) D) E) Br H Br H CH3 CH3 H CH2CH3 IV V I II III IV V Ans: E 108 Chapter 4 Topic: Conformational Analysis 53. The most stable conformation of 2,3-dimethylpentane, viewed through the C-2—C-3 bond (i.e., C-2 in the front, C-3 in the back): CH3 CH3 CH3 H H CH3 H CH2CH3 CH3 CH2CH3 H H H3C I CH3 H H CH(CH3)2 II III CH3 CH3 H CH3 H H3C CH3 CH3 CH(CH3)2 IV V H3CH2C A) B) C) D) E) H H H I II III IV V Ans: D Topic: Ring Strain 54. A) B) C) D) E) Which cycloalkane has the least ring strain? Cyclopropane Cyclobutane Cyclopentane Cyclohexane Cycloheptane Ans: D Topic: Conformational Analysis 55. The most stable conformation of cis-1-tert-butyl-2-methylcyclohexane is the one in which: A) the tert-butyl group is axial and the methyl group is equatorial. B) the methyl group is axial and the tert-butyl group is equatorial. C) both groups are axial. D) both groups are equatorial. E) the twist boat conformation is adopted. Ans: B 109 Chapter 4 Topic: Conformational Analysis 56. The most stable conformation of trans-1-tert-butyl-2-methylcyclohexane is the one in which: A) the tert-butyl group is axial and the methyl group is equatorial. B) the methyl group is axial and the tert-butyl group is equatorial. C) both groups are axial. D) both groups are equatorial. E) the molecule is in the half chair conformation. Ans: D Topic: Conformational Analysis 57. The most stable conformation of trans-1-tert-butyl-3-methylcyclohexane is the one in which: A) the tert-butyl group is axial and the methyl group is equatorial. B) the methyl group is axial and the tert-butyl group is equatorial. C) both groups are axial. D) both groups are equatorial. E) the twist boat conformation is adopted. Ans: B Topic: Conformational Analysis 58. A) B) C) D) E) In the most stable conformation of cis-1,4-dimethylcyclohexane, the methyl groups are: one axial, one equatorial. both axial. both equatorial. alternating between being both axial and both equatorial. None of the above Ans: A 110 Chapter 4 Topic: Conformational Analysis 59. The most stable conformation for 1,2-ethanediol (ethylene glycol) is shown below. It is the most stable conformation because: H H OH H OH H A) B) C) D) E) this corresponds to an anti conformation. in general, gauche conformations possess the minimum energy. it is stabilized by intramolecular hydrogen bonding. it is a staggered conformation. it has the highest energy of all the possibilities. Ans: C Topic: Conformational Analysis Relative energy 60. The graph below is a plot of the relative energies of the various conformations of: 0o 60o 120o 180o 240o 300o 360o Angle of rotation A) B) C) D) E) Ethane Propane Chloroethane 1-Chloropropane (C1-C2 rotation) Butane (C1-C2 rotation) Ans: D 111 Chapter 4 Topic: Conformational Analysis Relative energy 61. The graph below is a plot of the relative energies of the various conformations of: 0o A) B) C) D) E) 60o 120o 180o 240o 300o 360o Angle of rotation 2-chloropropane 1,3-dichloropropane 2-methylpropane Butane (C1-C2 rotation) Butane (C2-C3 rotation) Ans: E Topic: Conformational Analysis Relative energy 62. Consider the graph below, which is a plot of the relative energies of the various conformations of hexane, viewed through the C2-C3 bond. The conformations corresponding to the 60o and 300o are: 0o 60o 120o 180o 240o 300o 360o Angle of rotation A) B) C) D) E) Eclipsed Staggered, and gauche Staggered and anti More stable than the conformation at 180o None of the above Ans: B 112 Chapter 4 Topic: Conformational Analysis Relative energy 63. Consider the graph below, which is a plot of the relative energies of the various conformations of 2,3-dimethylbutane, viewed through the C2-C3 bond. The conformations corresponding to the 120o and 240o are: 0o A) B) C) D) E) 60o 120o 180o 240o 300o 360o Angle of rotation Eclipsed, more stable than the conformation at 0o Eclipsed, more stable than the conformation at 180o Staggered, more stable than the conformation at 0o Staggered, less stable than the conformation at 180o Two of the above are true Ans: A Topic: Conformational Analysis 64. Which conformation of trans-1-isopropyl-3-methylcyclohexane would be present in greatest amount at equilibrium? A) The conformation with the methyl group equatorial and the isopropyl group axial B) The conformation with the methyl group axial and the isopropyl group equatorial C) The conformation with both groups axial D) The conformation with both groups equatorial E) The twist boat conformation. Ans: B 113 Chapter 4 Topic: Conformational Analysis 65. Which conformation represents the most stable conformation of trans-1-bromo-4methylcyclohexane? CH3 Br Br Br CH3 CH3 I II III CH3 Br H3C Br IV A) B) C) D) E) V I II III IV V Ans: A Topic: Cis-Trans Isomers 66. Which of the following can be described as cis isomers? Br HO Cl Br F CH3 I II CH3 III CH3 HO CH2CH3 IV A) B) C) D) E) V I II, V III, IV I, III and IV None of the above are cis isomers. Ans: B 114 Chapter 4 Topic: Cis-Trans Isomers 67. Which of the following can be described as trans isomers? Br HO Cl Br F CH3 I II III CH3 CH3 HO CH2CH3 IV A) B) C) D) E) V I II, V III, IV I, III and IV None of the above are trans isomers. Ans: C Topic: Conformational Analysis 68. Which of the following will have the same energy after undergoing ring flip? OH HO Cl Br F CH3 I II CH3 III CH2CH3 HO CH2CH3 IV A) B) C) D) E) V I II III IV V. Ans: E 115 Chapter 4 Topic: Conformational Analysis 69. A) B) C) D) E) The least stable conformation of cyclohexane is the: boat. twist boat. chair. half-chair. twist chair. Ans: D Topic: Conformational Analysis 70. Express, quantitatively, the difference in stability of the two structures shown below. CH3 CH3 H3C H3C I A) B) C) D) E) II I is more stable than II by 7.5 kJ mol-1. I is more stable than II by 15 kJ mol-1. II is more stable than I by 7.5 kJ mol-1. II is more stable than I by 15 kJ mol-1. The two are equal in stability. Ans: A Topic: Conformational Analysis 71. A) B) C) D) E) The twist boat conformation is the preferred conformation for this compound. cis-1,4-Di-tert-butylcyclohexane trans-1,4-Di-tert-butylcyclohexane cis-1,3-Di-tert-butylcyclohexane trans-1,2-Di-tert-butylcyclohexane None of these Ans: A 116 Chapter 4 Topic: Ring Strain 72. Which of these C10H18 isomers is predicted to be the most stable? I A) B) C) D) E) II III H H H H IV V I II III IV V Ans: E Topic: Alkane Synthesis 73. A) B) C) D) E) Select the reagents necessary to convert cyclopentene into cyclopentane. H2 and Ni H2O Heat Zn, H3O+ Light Ans: A Topic: Alkane Synthesis 74. A) B) C) D) E) Select the reagents necessary to convert 3-bromohexane into hexane. Zn, H3O+ CuI H2O H3O+ OHAns: A 117 Chapter 4 Topic: General 75. A) B) C) D) E) How many constitutional isomers are possible for the formula C6H14? 2 3 4 5 6 Ans: D Topic: General 76. How many compounds with the formula C7H16 (heptanes) contain a single 3° carbon atom? A) 2 B) 3 C) 4 D) 5 E) 6 Ans: C Topic: Alkane Synthesis, Nomenclature 77. A) B) C) D) E) Catalytic hydrogenation of which of the following will yield 2-methylpentane? 2-methyl-1-pentene 2-methyl-2-pentene 4-methyl-2-pentene 4-methyl-1-pentene All of the above Ans: E 2 Topic: Alkane Synthesis, Nomenclature 78. The synthesis of an alkyne precursor to 2,2-dimethylheptane is accomplished most effectively by the reaction between these two reagents: A) CH3CH2CH2C≡CNa and (CH3)3CBr B) CH3CH2C≡CNa and (CH3)3CCH2Br C) (CH3)3CC≡CNa and CH3CH2CH2Br D) (CH3)3CCH2CH2C≡CH and CH3CH2I E) HC≡CNa and (CH3)3CCH2CH2Br Ans: C 118 Chapter 4 Topic: Alkane Synthesis, Nomenclature 79. The reaction of the Na salt of 3-methyl-1-pentyne with 1-bromo-3-methylbutane produces which of these? A) 3,8-dimethyl-4-nonyne B) 2,7-dimethyl-4-nonyne C) 3,8-dimethyl-5-nonyne D) 3,7-dimethyl-4-nonyne E) 3,7-dimethyl-5-nonyne Ans: A Topic: General 80. What is the simplest alkane, i.e., the one with the smallest molecular weight, which possesses primary, secondary and tertiary carbon atoms? A) 2-Methylpropane B) 2-Methylbutane C) 2-Methylpentane D) 3-Methylpentane E) 2,2-Dimethylbutane Ans: B Topic: General 81. A) B) C) D) E) How many alkanes of formula C7H16 possess a quaternary carbon atom? 1 2 3 4 5 Ans: C SHORT ANSWER QUESTIONS Topic: General 82. To determine the parent name for an alkane, we begin by finding the ___________________________. Ans: longest continuous chain of carbons 119 Chapter 4 Topic: Nomenclature 83. When more than one substituent is present on the parent chain, how do we organize the names of the substituents in the name of the compound? ___________________________. Ans: alphabetical order Topic: General 84. A compound containing two fused or bridged rings is referred to as a ___________________________. Ans: bicycloalkane Topic: General 85. A compound containing a triple bond between the first two carbons in the chain is called a ___________________________. Ans: terminal alkyne Topic: General 86. When non-bonded atoms/groups are closely positioned, the repulsive interactions between their electron clouds are referred to as ___________________________. Ans: steric hindrance Topic: General 87. _____________________ have the same molecular formula and connectivity but different arrangements of atoms in three-dimensional space. Ans: Stereoisomers Topic: Nomenclature 88. Alkanes in which some or all of the carbon atoms are arranged in a ring are called ___________________________. Ans: cycloalkanes Topic: Nomenclature 89. What is the fundamental principle of the IUPAC system of nomenclature for organic compounds? Ans: Each different compound should have an unambiguous name. 120 Chapter 4 Topic: Nomenclature 90. What are the four possible parts of a IUPAC name? Ans: locant, prefix, parent name, suffix Topic: General 91. In a bicyclic compound, the carbon atoms common to both rings are called ___________________________. Ans: bridgeheads Topic: Nomenclature 92. Give the IUPAC name corresponding to the following structure. Br OH Ans: 5-bromo-6-cyclopentyl-2-hexanol Topic: Nomenclature 93. Give the IUPAC name corresponding to the following structure: Br HO Ans: 3-(2-bromobutyl)cyclopentanol Topic: Nomenclature 94. Give the IUPAC name corresponding to the following structure: Br F Ans: trans-1-bromo-2-fluorocyclohexane Topic: Nomenclature 95. Give the IUPAC name corresponding to the following structure: HO Ans: 3-ethyl-6,7-dimethyl-2-octanol 121 Chapter 4 Topic: Nomenclature, Conformations 96. Draw the bond-line structural formula corresponding to the most stable conformation of the following substance: trans-1-bromo-3-(1-methylpropyl)cyclohexane Br Ans: Topic: Nomenclature 97. Draw the bond-line structural formula corresponding to the name: 2,5,9-trimethyl-2decen-7-yne Ans: Topic: Alkane Conformations 98. Draw the Newman projection formula for the gauche conformation of the C2-C3 bond in pentane. CH3 Ans: H CH2CH3 H H H Topic: Alkane Conformations 99. Draw the Newman projection formula for the most stable conformation of the C2-C3 bond in 3-methylpentane. CH3 Ans: CH3 H H H CH2CH3 Topic: Alkane Synthesis 100. Complete the following reaction sequence, giving structural details of A, B and C. NaH A Ans: C2H5Br NaH B H2,Ni C C2H5Br H2,Ni : Na+ A B 122 C Chapter 5 MULTIPLE CHOICE QUESTIONS Topic: Identifications and Comparisons 1. Which of the following is the enantiomer of the following substance? H H Br H CH3 CH3 Br H Br H H CH3 I A) B) C) D) E) Ans: CH3 H Br H II III I II III It does not have a non-superposable enantiomer. Both II and III D Topic: Identifications and Comparisons 2. Which of the following molecules is achiral? CO2H H H H3C C C H C OH HO2C CH3 Br H H Cl OH I II III CO2H H OH HO H CO2H IV A) B) C) D) E) Ans: F CH3 Br HO CH2CH3 V I II III IV V B 123 Chapter 5 Topic: Identifications and Comparisons 3. Hexane and 3-methylpentane are examples of: A) enantiomers. B) stereoisomers. C) diastereomers. D) constitutional isomers. E) None of these Ans: D Topic: Identifications and Comparisons 4. I and II are: CH2CH3 H3C A) B) C) D) E) Ans: Cl CH2Cl H H H CH2CH3 I II constitutional isomers. enantiomers. non-superposable mirror images. diastereomers. not isomeric. A 124 Chapter 5 Topic: Identifications and Comparisons 5. Pairs of enantiomers are: CH3 H3C H CH3 Cl Cl CH3 H3C CH2CH2CH3 CH2CH2CH3 CH2CH2CH3 I II III CH2Cl CH2CH2CH3 H3C H Cl H CH2CH2CH3 H A) B) C) D) E) Ans: Cl IV I, II and III, IV I, II III, IV IV, V None of the structures C V Topic: Identifications and Comparisons 6. Chiral molecules are represented by: CH3 H3C CH3 Cl Cl H CH3 H3C Cl C2H5 C2H5 C2H5 I II III C2H5 H3C Cl CH2Cl H H H C2H5 IV A) I, II, III, IV and V B) I, II, III and IV C) I and II D) III and IV E) IV alone Ans: D V 125 Chapter 5 Topic: Identifications and Comparisons 7. The molecules shown are: H H H OH H Br H Br H CH3 CH3 A) B) C) D) E) Ans: OH constitutional isomers. enantiomers. diastereomers. identical. None of these B Topic: Identifications and Comparisons The 8. The molecules shown are: H Cl H3CH2C H H Cl and Cl CH2CH3 Cl H CH2CH3 CH2CH3 A) B) C) D) E) Ans: are enantiomers. diastereomers. constitutional isomers. two conformations of the same molecule. not isomeric. B Topic: Identifications and Comparisons 9. The molecules shown are: CH3 H F H H CH3 F A) B) C) D) E) Ans: H constitutional isomers. enantiomers. diastereomers. identical. None of these B 126 Chapter 5 Topic: Identifications and Comparisons 10. The molecules below are: F H H H F H F F A) B) C) D) E) Ans: constitutional isomers. enantiomers. diastereomers. identical. stereoisomers. A Topic: Identifications and Comparisons 11. The molecules shown are: H CH3 Cl H Cl CH3 H Cl Cl H CH3 A) B) C) D) E) Ans: CH3 enantiomers. diastereomers. constitutional isomers. two different conformations of the same molecule. not isomeric. A Topic: Identifications and Comparisons 12. The molecules shown are: H CH3 OH H OH H H CH3 A) B) C) D) E) Ans: constitutional isomers. enantiomers. diastereomers. identical. None of these B 127 Chapter 5 Topic: Identifications and Comparisons 13. The molecules shown are: A) B) C) D) E) Ans: H H F F constitutional isomers. enantiomers. diastereomers. identical. None of these E Topic: Identifications and Comparisons 14. The molecules below are: CH3 H H H H CH3 CH3 CH3 A) B) C) D) E) Ans: structural isomers. enantiomers. diastereomers. identical. None of these C Topic: Identifications and Comparisons 15. Cis-trans isomers are: A) diastereomers. B) enantiomers. C) stereoisomers. D) constitutional isomers. E) More than one of these Ans: E 128 Chapter 5 Topic: Identifications and Comparisons 16. The molecules below are: Cl CH3 Cl Br F A) B) C) D) E) Ans: F Br CH3 I II constitutional isomers. enantiomers. diastereomers. identical. None of these D Topic: Identifications and Comparisons 17. The molecules below are: CH3 CH3 H F CH3 H2N F H H3C F F A) B) C) D) E) Ans: NH2 constitutional isomers. enantiomers. diastereomers. identical. None of these C Topic: Identifications and Comparisons 18. The molecules shown are: A) B) C) D) E) Ans: H CH3 F F constitutional isomers. enantiomers. diastereomers. identical. None of these A 129 Chapter 5 Topic: Identifications and Comparisons 19. The molecules below are: Cl CH3 F F Cl CH3 H A) B) C) D) E) Ans: H constitutional isomers. enantiomers. diastereomers. identical. None of these D Topic: Identifications and Comparisons 20. The molecules below are: H H H H CH3 Cl A) B) C) D) E) Ans: Cl CH3 constitutional isomers. enantiomers. diastereomers. identical. None of these B 130 Chapter 5 Topic: Identifications and Comparisons 21. Which molecule is achiral? H Cl H Cl Br H Br Cl Br Br H H Cl Cl Br Cl Br Br I II III A) B) C) D) E) Ans: I II III More than one of these None of these A Topic: Identifications and Comparisons 22. Which molecule is achiral? H Br Br H Br Cl H Cl H H Br Cl Br Br Cl Cl H H I II III A) B) C) D) E) Ans: I II III More than one of the above None of the above C 131 Chapter 5 Topic: Identifications and Comparisons 23. The molecules below are: H H H F F H H F H H H H H F H H I II A) B) C) D) E) Ans: constitutional isomers. enantiomers. diastereomers. identical. None of these A Topic: Identifications and Comparisons 24. The structures H CH3 CH3 CH3 H H H CH3 represent: A) a single compound. B) enantiomers. C) meso forms. D) diastereomers. E) conformational isomers. Ans: A 132 Chapter 5 Topic: Identifications and Comparisons 25. Which pair of structures represents the same compound? CH3 OH H H H OH OH CH3 CH3 H OH H HO OH H CH3 CH3 OH H H HO H HO CH3 CH3 H HO H HO H OH CH3 CH3 OH H OH H HO H CH3 II III IV V I A) B) C) D) E) Ans: I and II II and III III and IV III and V IV and V D Topic: Identifications and Comparisons 26. Which structure(s) represent(s) diastereomer(s) of I? CH3 OH H HO H HO H CH3 CH3 H OH H HO OH H CH3 I II A) B) C) D) E) Ans: CH3 OH H OH H OH H CH3 III II II and III II and IV III and V IV and V B 133 CH3 H HO H HO H OH CH3 CH3 OH H OH H HO H CH3 IV V Chapter 5 Topic: Identifications and Comparisons 27. The two compounds shown below are: Br Cl H F H Br F A) B) C) D) E) Ans: Cl enantiomers. diastereomers. constitutional isomers. identical. different but not isomeric. A Topic: Identifications and Comparisons 28. The two compounds shown below are: Br Br H H A) B) C) D) E) Ans: Br H and H Br are: identical. enantiomers. diastereomers. conformational isomers. meso forms. B Topic: Identifications and Comparisons 29. (2R,4S) –2,4–Dichloropentane and (2S,4R)-2,4-dichloropentane are: A) enantiomers B) diastereomers C) identical D) conformational isomers E) constitutional isomers Ans: C 134 Chapter 5 Topic: Meso compounds 30. Which of the following is a meso compound? H HO H3C H2 C OH CH3 H H3C HO H H II I CH2OH CH2OH CH3 H OH CH3 OH H H H OH CH2OH CH2OH CH3 III IV V A) B) C) D) E) Ans: I II III IV V A Topic: Meso compounds 31. Which of the following is(are) meso compound(s)? CH3 H CH3 Cl CH3 Cl H H Cl H Cl H Cl H Cl CH3 CH3 CH3 I II III A) B) C) D) E) Ans: I II III Both II and III Both I and III E 135 Chapter 5 Topic: Meso compounds 32. Which of the following molecules is achiral? A) (2R,3R)-2,3-Dichloropentane B) (2R,3S)-2,3-Dichloropentane C) (2S,4S)-2,4-Dichloropentane D) (2S,4R)-2,4-Dichloropentane E) Two of these Ans: D Topic: Meso compounds 33. Which of the following is(are) meso? Br Br H H Br H Br Br I II A) B) C) D) E) Ans: Br Br H H III Topic: Meso compounds 34. Which molecule has a plane of symmetry? Cl H H H Cl Cl H H CH3 I II A) I B) II C) III D) More than one of these E) None of these Ans: D H IV I II III IV Two of the above E F Br H H CH3 CH3 III 136 Chapter 5 Topic: Meso compounds 35. Which molecule has a plane of symmetry? H CH2CH3 CH3 HO H HO CH3 I A) B) C) D) E) Ans: CH3 H H F F II III I II III More than one of these None of these D Topic: Meso compounds 36. Which compound does NOT possess a plane of symmetry? H H Cl F F H I A) B) C) D) E) Ans: II H CH3 H Br CH3 Br Br H Br III I, II and V I, III and IV II, III and IV III and IV V D 137 IV H3C V Chapter 5 Topic: Meso compounds 37. Which molecule is a meso compound? H H CH3 H Br H3C H Br H OH H3C F H F CH3 CH3 OH CH3 I II III A) B) C) D) E) Ans: I II III More than one of the above None of the above D Topic: Meso compounds 38. Which molecule is a meso compound? H H H F H H H CH3 F CH3 OH F F H H F H CH3 F CH3 I A) B) C) D) E) Ans: II III IV I and II IV and V II and III I, II and III None of the above E 138 V Chapter 5 Topic: Meso compounds 39. Which of the following substances is achiral ? Cl H H F H H CH3 F H Br I A) B) C) D) E) Ans: II CH3 Br H III HO IV I II III IV More than one of these E Topic: Meso compounds 40. Which statement is not true for a meso compound? A) The specific rotation is 0º. B) There are one or more planes of symmetry. C) A single molecule is identical to its mirror image. D) More than one stereogenic center must be present. E) The stereochemical labels, (R) and (S), must be identical for each stereogenic center. Ans: E Topic: Meso compounds 41. Which is a meso compound? A) (2R,3R)-2,3-Dibromobutane B) (2R,3S)-2,3-Dibromopentane C) (2R,4R)-2,4-Dibromopentane D) (2R,4S)-2,4-Dibromopentane E) (2R,4S)-2,4-Dibromohexane Ans: D 139 Chapter 5 Topic: Specific names 42. (R)-2-Chlorobutane is represented by: H3C A) B) C) D) E) Ans: Cl H CH3 CH3 Cl CH3 H3C CH2Cl CH2CH3 Cl H3C Cl H H CH2CH3 CH2CH3 CH2CH3 H CH2CH3 I II III IV V CH3 CH2CH3 I II III IV V C Topic: Specific names 43. Which of the following represent (R)-2-butanol? H3C A) B) C) D) E) Ans: H CH3 H OH H OH HO CH3 HO H H OH CH2CH3 CH2CH3 CH2CH3 CH2CH3 CH3 I II III IV V III and V I, III, IV and V I, IV and V I and III I, II, IV and V C 140 Chapter 5 Topic: Specific names 44. Which structure represents (S)-1-chloro-1-fluoroethane? Cl CH3 F F H H Cl H Cl CH3 CH3 F I II III A) B) C) D) E) Ans: I II III More than one of the above None of the above D Topic: Specific names 45. Which structure represents (R)-1-chloro-1-fluoroethane? Cl CH3 F F H H Cl H Cl CH3 CH3 F I II III A) B) C) D) E) Ans: I II III More than one of the above None of the above B 141 Chapter 5 Topic: Specific names 46. Which structure represents (S)-2-bromobutane? H H CH3 CH3 Br Br H H3C Br CH2CH3 CH2CH3 CH2CH3 I II III A) B) C) D) E) Ans: I II III More than one of the above None of the above A Topic: Specific names CH2CH3 47. H Cl H CH3 Cl H CH3 A) B) C) D) E) Ans: is properly named: (3R,4S,5R)- 3,5-Dichloro-4-methylhexane (2S,3S,4S)- 2,4-Dichloro-3-methylhexane (2S,3R,4R)- 2,4-Dichloro-3-methylhexane (2S,3R,4S)-2,4-Dichloro-3-methylhexane (2S,3S,4R)- 2,4-Dichloro-3-methylhexane D 142 Chapter 5 Topic: Specific names 48. The Cahn-Ingold-Prelog stereochemical designations used for the following substance are: H Cl Cl H Cl A) B) C) D) E) Ans: Cl 2R,4S 2S,4R 2R,4R 2S,4S The “R,S” terminology doesn't apply in this case. C Topic: Specific names 49. Which of these is not a correct Fischer projection formula of the (S) form of 3-bromo-1,1-dichloro-2-propanol ? CHCl2 H OH CH2Br I A) B) C) D) E) Ans: CH2Br HO H CHCl2 II H Cl2HC CH2Br OH OH CHCl2 H CH2Br IV III OH CHCl2 BrH2C H V I II III IV V D Topic: Optical activity 50. What is the percent composition of a mixture of (S)-(+)-2-butanol,[α] 25 = +13.52º, D = -13.52º, with a specific rotation [α] 25 = +6.76º? and (R)-(-)-2-butanol,[α] 25 D D A) 75%(R) 25%(S) B) 25%(R) 75%(S) C) 50%(R) 50%(S) D) 67%(R) 33%(S) E) 33%(R) 67%(S) Ans: B 143 Chapter 5 Topic: Optical activity 51. Which one of the following can exist in optically active forms? A) cis-1,3-Dichlorocyclohexane B) trans-1,3-Dichlorocyclohexane C) cis-1,4-Dichlorocyclohexane D) trans-1,4-Dichlorocyclohexane E) cis-1,2-Dichlorocyclohexane Ans: B Topic: Optical activity 52. The compounds whose molecules are shown below would have: CH2CH3 CH3 H F H F CH2CH3 CH3 I II A) B) C) D) E) Ans: the same melting point. different melting points. equal but opposite optical rotations. More than one of the above None of the above D Topic: Optical activity 53. The compounds whose molecules are shown below would have: CH3 CH3 H F H CH3 F A) B) C) D) E) Ans: F H H3C F H the same melting point. different melting points. equal but opposite optical rotations. More than one of the above None of the above B 144 Chapter 5 Topic: Optical activity 54. The compounds whose molecules are shown below would have: H H H OH OH A) B) C) D) E) Ans: the same melting point. different melting points. equal but opposite optical rotations. More than one of these None of these B H OH OH Topic: Optical activity 55. The compounds whose structures are shown below would have: CH3 Br CH3 Br Br CH3 Br A) B) C) D) E) Ans: the same melting point. different melting points. equal but opposite optical rotations. More than one of these None of these D CH3 145 Chapter 5 Topic: Optical activity 56. A solution of which of these allenes will rotate plane-polarized light? H H C C H H C H C H C Cl I H C C H H C C Cl Cl Cl Cl C C Cl C Cl V IV A) B) C) D) E) Ans: C III C Cl C Cl II Cl H I II III IV V C Topic: Optical activity 57. How many optically active compounds are represented by the following generalized formula? BrHC A) B) C) D) E) Ans: CHBr 0 1 2 3 4 C 146 Chapter 5 Topic: Optical activity 58. Which of these is a comparatively insignificant factor affecting the magnitude of specific optical rotation? A) Concentration of the substance of interest B) Purity of the sample C) Temperature of the measurement D) Length of the sample tube E) All of the above are equally significant. Ans: C Topic: Optical activity 59. What can be said with certainty if a compound has [α] 25 = -9.25º ? D A) The compound has the (S) configuration. B) The compound has the (R) configuration. C) The compound is not a meso form. D) The compound possesses only one stereogenic center. E) The compound has an optical purity of less than 100%. Ans: C Topic: Optical activity 60. An alkane which can exhibit optical activity is: A) Neopentane B) Isopentane C) 3–Methylpentane D) 3–Methylhexane E) 2,3–Dimethylbutane Ans: D Topic: Optical activity 61. In the absence of specific data, it can only be said that (R)–2–bromopentane is: A) dextrorotatory (+). B) levorotatory (–). C) optically inactive. D) achiral. E) analogous in absolute configuration to (R)–2–chloropentane. Ans: E 147 Chapter 5 Topic: Optical activity 62. If a solution of a compound (30.0 g/100 mL of solution) has a measured rotation of +15º in a 2 dm tube, the specific rotation is: A) +50º B) +25º C) +15º D) +7.5º E) +4.0º Ans: B Topic: Optical activity 63. Which compound would show optical activity? A) cis 1,4- Dimethylcyclohexane B) trans 1,4- Dimethylcyclohexane C) cis 1,4- Dimethylcycloheptane D) trans 1,4- Dimethylcycloheptane E) More than one of these Ans: D Topic: Optical activity 64. Of the compounds which correspond to the general name "dichlorocyclobutane", how many are optically active? A) 0 B) 1 C) 2 D) 3 E) 4 Ans: C Topic: General definitions 65. Which of the following is true about any (R)-enantiomer? A) It is dextrorotatory. B) It is levorotatory. C) It is an equal mixture of + and -. D) It is the mirror image of the (S)-enantiomer. E) (R) indicates a racemic mixture. Ans: D 148 Chapter 5 Topic: General definitions 66. Which of the following is true of any (S)-enantiomer? A) It rotates plane-polarized light to the right. B) It rotates plane-polarized light to the left. C) It is a racemic form. D) It is the mirror image of the corresponding (R)-enantiomer. E) It has the highest priority group on the left. Ans: D Topic: General definitions 67. Enantiomers are: A) molecules that have a mirror image. B) molecules that have at least one stereogenic center. C) non-superposable molecules. D) non-superposable constitutional isomers. E) non-superposable molecules that are mirror images of each other. Ans: E Topic: General definitions 68. Which of the following is NOT true of enantiomers? They have the same: A) boiling point. B) melting point. C) specific rotation. D) density. E) chemical reactivity toward achiral reagents. Ans: C Topic: General definitions 69. Which statement is true of 1,3-dimethylcyclobutane? A) Only one form of the compound is possible. B) Two diastereomeric forms are possible. C) Two sets of enantiomers are possible. D) Two enantiomeric forms and one meso compound are possible. E) None of the previous statements is true. Ans: B 149 Chapter 5 Topic: Reaction stereochemistry 70. In which of the following reactions is the absolute configuration of the product likely to be the same as that of the reactant? Br Br A) PBr3 (R) OH Br O B) Br (R) OH Br OH O HA O Br C) OH H2O OH (R) D) All of the above E) Answers A) and B) only Ans: E OH Topic: Reaction Stereochemistry 71. Which of the following reactions must occur with retention of configuration? KMnO4 A) (R) OH O POCl3 B) (R) OH Cl C) (S) OH (R) O OCH3 OH D) Cl NH2 NH3 OH O OCH3 Cl PCl5 O O Cl E) (S) OH P, Cl2 Cl O Cl O Ans: D 150 OH Chapter 5 Topic: Reaction stereochemistry 72. Which reaction must take place with retention of configuration at the stereogenic center? OH Cl HCl A) F Br F OH B) PCl3 O C) F OH F Br F Cl O O F O O D) More than one of the above E) None of the above Ans: D Topic: Reaction stereochemistry 73. O The reaction of with H2/Ni forms: A) 2-methylheptane. B) (R)-2-methyl-5-heptanol C) (S)-6-methyl-3-heptanol D) (R,S)-6-methyl-3-heptanol E) Achiral 6,6-dimethyl-3-hexanol Ans: D Topic: General stereochemistry 74. CH3CHBrCH2CHClCH3 is the generalized representation of what number of stereoisomers? A) 3 B) 4 C) 5 D) 6 E) 7 Ans: Bs 151 Chapter 5 Topic: General stereochemistry 75. For the generalized structure BrCH2CHClCH2CHClCH2Br there exists what number of stereoisomers? A) 2 B) 3 C) 4 D) 6 E) 8 Ans: B Topic: General stereochemistry 76. How many discrete dimethylcyclopropanes are there? A) 2 B) 3 C) 4 D) 5 E) 6 Ans: C Topic: General stereochemistry 77. What is the molecular formula for the alkane of smallest molecular weight which possesses a stereogenic center? A) C4H10 B) C5H12 C) C6H14 D) C7H16 E) C8H18 Ans: D Topic: General stereochemistry 78. How many chiral stereoisomers can be drawn for CH3CHFCHFCH(CH3)2? A) 1 B) 2 C) 3 D) 4 E) 8 Ans: D 152 Chapter 5 Topic: General stereochemistry 79. How many different compounds are there which correspond to the general name "3-(1methylbutyl)cyclobutanol”? A) 2 B) 4 C) 6 D) 8 E) None of the above Ans: B Topic: General stereochemistry 80. How many stereogenic centers are there in Lovastatin ( Mevacor® : a cholesterollowering drug) ? HO O O O (Lovastatin) A) 4 B) 5 C) 6 D) 7 E) 8 Ans: E Topic: General stereochemistry 81. What is the total number of compounds, stereoisomers included, designated by the general name "dichlorocyclopentane"? A) 4 B) 5 C) 7 D) 8 E) 9 Ans: C 153 Chapter 5 Use the following to answer questions 82-85: Consider the following compounds: H CH2OH H OH H H CH3 HO CH3 HO H H CH3 HO CH3 CH3 OH H H3C H CH3 OH H OH I II III IV Topic: General stereochemistry 82. Which of the compounds above (I-IV) represent enantiomers? A) I and II B) II and III C) III and IV D) II and IV E) III and IV Ans: B Topic: General stereochemistry 83. Which compound above (I-IV) is a meso compound? A) I B) II C) III D) IV E) None of these Ans: D Topic: General stereochemistry 84. Which compound above (I-IV) is (2R,3R)-2,3-butanediol? A) I B) II C) III D) IV E) None of these Ans: C 154 Chapter 5 Topic: General stereochemistry 85. Which compounds above (I-IV) form a set of stereoisomers? A) I, II and III B) II, III and IV C) II and III D) I, III and IV E) I, II, III and IV Ans: B SHORT ANSWER QUESTIONS Topic: General stereochemistry 86. To be superposable, when one object is placed on top of another, _________________. Ans: all parts of each object must coincide Topic: General stereochemistry 87. An achiral molecule is one that is __________________ upon its mirror image. Ans: superposable Topic: General stereochemistry 88. Enantiomers are stereoisomers whose molecules are ____________________. Ans: nonsuperposable mirror images Topic: General stereochemistry 89. A chiral molecule is defined as one that is _____________________ on its mirror image. Ans: nonsuperposable Topic: General stereochemistry 90. A meso compound has __________ chiral center(s), and is __________ upon its mirror image. Ans: two or more, superposable 155 Chapter 5 Topic: General stereochemistry 91. The molecule of aspartame ( Nutrasweet® ), depicted below, has ___________ ( how many? ) stereogenic centers. O O HO HN O H2N O Aspartame Ans: two Topic: General stereochemistry 92. All molecules with a plane of symmetry are _________. Ans: achiral Topic: General stereochemistry 93. When using the Cahn-Ingold-Prelog rules for prioritizing groups on a stereogenic carbon, priority is first assigned on the basis of ____________________. Ans: atomic number Topic: General stereochemistry 94. Enantiomers have ______________ physical properties. Ans: identical Topic: General stereochemistry 95. The device that is used for measuring the effect of optically active compounds on planepolarized light is called a ________________. Ans: polarimeter Topic: General stereochemistry 96. True or false: A sample consisting of the pure R enantiomer of a compound will always rotate plane-polarized light in a clockwise direction. A) True B) False Ans: B 156 Chapter 5 Topic: General stereochemistry 97. An equimolar mixture of two enantiomers is called a ________________. Ans: racemic mixture Topic: General stereochemistry 98. A molecule that contains stereogenic carbons but is nonetheless achiral is referred to as a ______________. Ans: meso compound Topic: General stereochemistry 99. When discussing the stereochemical relationship of cis/trans isomers of cyclic compounds, we refer to them as __________________. Ans: diastereomers Topic: Nomenclature 100. Draw a dash-wedge structure for (3R)-3-methyl-5-hexen-3-ol OH Ans: Topic: Nomenclature 101. Draw a dash-wedge structure for (1R)-1-bromo-1,3,3-trimethylcyclohexane Ans: Br Topic: Nomenclature 102. Draw a dash-wedge structure for (1R,3R)-1,3-dibromo-1,3-dimethylcyclohexane Ans: Br Br 157 Chapter 5 Topic: Nomenclature 103. Draw a dash-wedge structure for (1S,3R)-1-ethyl-1,3-dimethylcyclopentane CH3 Ans: C2H5 H CH3 Topic: Nomenclature 104. What is the complete IUPAC name of the following substance? (Remember to give stereochemical details, as relevant.) H C2H5 H3C CH3 Ans: (1S)-1-ethyl-1,3,3-trimethylcyclopentane Topic: Nomenclature 105. What is the complete IUPAC name of the following substance? (Remember to give stereochemical details, as relevant.) H OH H3C OH Ans: (1R,3S)-1-methylcyclopentane-1,3-diol 158 Chapter 5 Topic: Fischer projections 106. Draw Fischer projection formulas for all stereoisomers of 2,4-dibromohexane, giving stereochemical details for each structure. CH3 CH3 CH3 CH3 Ans: Br H H Br H Br H H H H H H H Br H H Br Br H H Br H H H H H H H H H Br H CH3 CH3 CH3 CH3 2R,4S 2S,4R 2S,4S 2R,4R 2,4-dibromohexane Topic: Stereoisomers 107. Draw dash-wedge structures for all stereoisomers of 1-bromo-3-isopropylcyclohexane, giving stereochemical details for each structure. Ans: H H H H Br 1S, 3R H Br H H 1R, 3S Br 1S, 3S 1-bromo-3-isopropylcyclohexane 159 Br H 1R, 3R Chapter 5 Topic: Fischer projections 108. Draw Fischer projection formulas for all stereoisomers of 2,4-dimethyl-3-hexanol, giving stereochemical details for each structure. Ans: CH3 H3C CH3 H H OH CH3 CH3 H3C H H3C H HO H H OH H3C H H CH3 H CH3 H H H H H H H3C H HO H H3C H H H CH3 CH3 CH3 CH3 3S,4S 3R,4R 3S,4R 3R,4S 2,4-dimethyl-3-hexanol Topic: Fischer projections 109. Draw a Fischer projection formula of (3R)-6-Bromo-1-hexen-3-ol. H2C H Ans: * OH Br H OH H H H H CH2Br (3R)-6-Bromo-1-hexen-3-ol. 160 Chapter 6 MULTIPLE CHOICE QUESTIONS Topic: Reaction kinetics 1. Consider the SN2 reaction of butyl bromide with OH- ion. CH3CH2CH2CH2Br + OH- ⎯⎯⎯⎯→ CH3CH2CH2CH2OH + Br- A) B) C) D) E) Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both butyl bromide and OH- ion? No effect. It would double the rate. It would triple the rate. It would increase the rate four times. It would increase the rate six times. Ans: D Topic: Reaction kinetics − 2. Consider the SN2 reaction of 2-iodopentane with CH3CO2 ion. I O O O NaI ONa Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both 2-iodopentane and CH3CO2− ion? A) B) C) D) E) No effect. It would double the rate. It would triple the rate. It would increase the rate four times. It would increase the rate six times. Ans: D 161 Chapter 6 Topic: Reaction kinetics − 3. Consider the SN2 reaction of 1-chloro-5-methylhexane with CN ion. Cl NaCN CN NaCl Assuming no other changes, what effect on the rate would result from simultaneously doubling the concentrations of both 1-chloro-5-methylhexane and CN− ion? A) B) C) D) E) No effect. It would double the rate. It would triple the rate. It would increase the rate four times. It would increase the rate six times. Ans: D Topic: Reaction kinetics 4. Select the rate law for the following reaction, e.g., CH3CH2CH2CHBrCH3 + OH− ⎯⎯⎯→ CH3CH2CH2CHOHCH3 + X− ( RBr ) A) Rate = k [RBr] B) Rate = k [RBr] [OH−] C) Rate = k [RBr]2 [OH−] D) Rate = k [RBr] [OH−]2 E) Rate = k [RBr]2 [OH−]2 Ans: B Topic: Activation Energy 5. Increasing the temperature of a chemical reaction usually increases greatly the rate of the reaction. The most important reason for this is that increasing the temperature: A) Increases the collision frequency. B) Decreases the probability factor. C) Increases the fraction of collisions with energy greater than Eact. D) Decreases the energy of activation. E) Makes the reaction more exothermic Ans: C 162 Chapter 6 Topic: Activation Energy 6. Increasing the temperature of a chemical reaction usually increases greatly the rate of the reaction. The primary reason for this is that increasing the temperature: A) Decreases the energy of activation. B) Increases the total number of collisions between reactants C) Decreases the rate of the reverse reaction. D) Favors endothermic processes. E) None of the above properly explains the observed increase in reaction rates with increase in temperature. Ans: E Topic: Reaction Kinetics 7. The rate equation for a nucleophilic substitution reaction of a tertiary alkyl bromide (RBr) with I− ion would be: A) Rate = k [RBr] B) Rate = k [I−] C) Rate = k [RBr][I−] D) Rate = k [RBr]2[I−] E) Rate = k [RBr][I−]2 Ans: A Topic: Reaction Kinetics 8. The rate equation for a nucleophilic substitution reaction of a secondary alkyl chloride (R-Cl) with I− ion would be: A) Rate = k [RCl] B) Rate = k [I−] C) Rate = k [RCl][I−] D) Rate = k [RCl]2[I−] E) Rate = k [RCl][I−]2 Ans: C 163 Chapter 6 Topic: Reaction Kinetics 9. Consider the reaction of 2-chloro-2-methylpentane with sodium iodide. NaI NaCl Cl A) B) C) D) E) I Assuming no other changes, how would it affect the rate if one simultaneously doubled the concentration of 2-chloro-2-methylpentane and sodium iodide? No effect It would double the rate. It would triple the rate. It would quadruple the rate. It would increase the rate five times. Ans: B Topic: Predicting mechanisms, products 10. What would you expect to be the chief organic product(s) when tert-butyl bromide reacts with sodium acetylide, i.e., Br I HC C: ? Na II III HC CH IV A) B) C) D) E) I II III IV None of these Ans: D 164 Chapter 6 Topic: Predicting mechanisms, products 11. What would you expect to be the chief organic product(s) when 2-bromo-2methylpentane reacts with sodium propynide, i.e., Br C: I ? Na III II HC CH HC IV A) B) C) D) E) CH V I II III IV V Ans: D Topic: Predicting products 12. What product(s) would you expect to obtain from the following SN2 reaction? H H CH3 Br CH3OH H H H OCH3 CH3 OCH3 CH3 H I A) B) C) D) E) CH3ONa ? CH3O H H Br II III I II An equimolar mixture of I and II. III None of these Ans: B 165 Chapter 6 Topic: Predicting mechanisms, products 13. What major product(s) are likely to be obtained from the following reaction? H H Cl CH3CH2ONa CH3CH2OH, 65oC H H O I A) B) C) D) E) H ? O O H H H Cl II III I, by predominantly SN2 II, by predominantly SN2 An equimolar mixture of I and II, by predominantly SN1. III, by substitution of the alkyl group, rather than substitution of the chloro group Actually, none of these products are likely to be obtained as major products, because elimination will probably predominate, leading to the formation of an alkene. Ans: E Topic: Predicting mechanisms, products 14. Treating (CH3)3C-Cl with a mixture of H2O and CH3OH at room temperature would yield: A) CH2=C(CH3)2 B) (CH3)3COH C) (CH3)3COCH3 D) All of these E) None of these Ans: D 166 Chapter 6 Topic: Predicting mechanisms, products 15. Treating 1-bromo-1-methylcyclohexane with CH3OH at room temperature would yield: A) OCH3 B) C) D) All of these E) None of these Ans: D Topic: Predicting products 16. The major product of the following reaction would be: C H 2C l H OCH3 − OH SN2 ? CH3 C H 2O H H 3C O H C H 2O H H CH3 OCH3 CH3 II I C H 2C l C H 2C l HO A) B) C) D) E) H H OH CH3 CH3 III IV I II III IV An equimolar mixture of I and II. Ans: B 167 Chapter 6 Topic: Predicting mechanisms, products 17. Which would be formed in the following reaction? CH3 H 3C Br C H 3O H ? 55 o C H CH3 OCH3 H 3C CH3 H 3C OCH3 H H I A) B) C) D) E) II CH3 CH3 CH3 CH2 III IV I II III IV All of the above Ans: E 168 Chapter 6 Topic: Predicting mechanisms, products 18. Which would be formed in the following reaction? CH3 Br H3C O OH ? 50oC H O CH3 O O H3C CH3 H3C H H A) B) C) D) E) O I II III IV I II III IV All of the above Ans: E 169 Chapter 6 Topic: Predicting mechanisms, products 19. Which would be the major product of the following reaction? CH3 H H CH3 (CH3)3CO− ? (CH3)3COH 55oC Cl OC(CH3)3 CH3 H H3C H3C H I I A) B) C) D) E) OC(CH3)3 H II III I II III IV None of the above Ans: C 170 IV Chapter 6 Topic: Predicting mechanisms, products 20. When 1,4-diiodo-2,2-dimethylbutane (0.10 mol) is treated with 0.10 mol of NaCN in dimethyl sulfoxide at 30°C, the product formed is: I A) NC B) CN I C) both A) and B). D) E) CN NC I Ans: B Topic: Predicting mechanisms, products 21. The major product(s) of the following reaction is(are): H NaI, CH3CH2OH H 25oC Cl CH3 H I H H H I A) B) C) D) E) H OCH2CH3 H CH3 CH3 CH3 CH3 I II III IV I II III IV Equal amounts of I and II Ans: A 171 Chapter 6 Topic: Predicting products 22. What would be the major product of the following reaction? CH2Cl H CH3 OH − SN2 CH2OH H3C CH2OH H H CH3 II I CH2Cl HO CH3 III A) B) C) D) E) CH2Cl H OH IV I II III IV An equimolar mixture of I and II Ans: B 172 Chapter 6 Topic: Predicting mechanisms, products 23. What would be the major product(s) of the following reaction? CH3 H3C CH3O− / CH3OH 55oC Br H CH3 H3C OCH3 H A) B) C) D) E) II CH3 III CH3 H I H3C OCH3 H3C H3C IV I II III and IV I and II All of the above Ans: C 173 Chapter 6 Topic: Predicting mechanisms, products 24. What would be the major product of the following reaction? − H CΝ Br 25oC H3C H H H3C CN H CN H3C Br H I II CN H3C H H H H3C Br NC III A) B) C) D) E) IV I II III IV Equal amounts of I and III Ans: C Topic: Predicting mechanisms, products 25. What would be the major product obtained when trans-1-bromo-3-methylcyclopentane is allowed to react with NaSH at 25oC? H H3C H SH H3C H I A) B) C) D) E) SH H3C SH H3C H Br HS H II III I II III IV Equal amounts of I and II Ans: B 174 H Br IV Chapter 6 Topic: Synthesis, reagent selection 26. You want to synthesize 3-methyl-2-pentene from 2-chloro-3-methylpentane. Which reagent would you use? A) HCl, heat B) NH3(aq), 25oC C) CH3CO2Na, CH3CO2H, heat D) CH3CH2ONa, CH3CH2OH, heat E) CH3CH2OH, heat Ans: D Topic: Predicting mechanisms, products 27. When tert-pentyl chloride undergoes solvolysis in aqueous ethanol at room temperature, there is/are formed: A) OH B) OC2H5 C) D) E) All of these Ans: E Topic: Predicting mechanisms, products 28. A) B) C) D) E) Reaction of sodium ethoxide with 1-bromopentane at 30°C yields primarily: CH3CH2CH2CH=CH2 CH3CH2CH=CHCH3 CH3CH2CH2CH2CH3 CH3CH2CH2CH2CH2OH CH3CH2CH2CH2CH2OCH2CH3 Ans: E 175 Chapter 6 Topic: Predicting mechanisms, products 29. Heating an alcoholic solution of sodium hydroxide and 1-bromopentane at 60°C yields primarily: A) B) C) OH D) O E) Ans: D Topic: Predicting mechanisms, products 30. If 0.10 mol of HSCH2CH2OH reacts at 25°C, sequentially, with 0.20 mol of NaH, 0.10 mol of CH3CH2Br and H2O, which is the major product? A) HSCH2CH2OCH2CH3 B) CH3CH2SCH2CH2OH C) CH3CH2SCH2CH2OCH2CH3 D) CH2=CH2 E) CH3CH3 Ans: B Topic: Predicting mechanisms, products 31. When 0.10 mol of ICH2CH2CH2CH2Cl reacts with 0.10 mol of NaOCH3 in CH3OH at 40°C, the major product is: A) CH3OCH2CH2CH2CH2Cl B) CH3OCH2CH2CH2CH2I C) CH3OCH2CH2CH2CH2OCH3 D) CH2=CHCH2CH2Cl E) CH2=CHCH2CH2I Ans: A Topic: Generalities 32. A) B) C) D) E) SN2 reactions of the type, Nu- + RL ⎯⎯⎯⎯→ Nu-R + L-, are favored: when tertiary substrates are used. by using a high concentration of the nucleophile. by using a solvent of high polarity. by the use of weak nucleophiles. by none of the above. Ans: B 176 Chapter 6 Topic: Generalities 33. Which of the following statements is (are) true of SN1 reactions of alkyl halides in general? A) The rate of an SN1 reaction depends on the concentration of the alkyl halide. B) The rate of an SN1 reaction depends on the concentration of the nucleophile. C) SN1 reactions of alkyl halides are favored by polar solvents. D) Answers A) and C) only are true. E) Answers A), B) and C) are true. Ans: D Topic: Generalities 34. Which of the following statements is (are) true of SN1 reactions of alkyl halides in general? A) The rate of an SN1 reaction depends on the concentration of the alkyl halide. B) The rate of an SN1 reaction depends on the concentration of the nucleophile. C) SN1 reactions of alkyl halides occur faster in polar aprotic solvents (compared to protic solvents) D) Answers A) and C) only are true. E) Answers A), B) and C) are true. Ans: A Topic: Generalities 35. A) B) C) D) E) SN1 reactions of the type, Nu- + RL ⎯⎯⎯⎯→ Nu–R + L-, are favored: when tertiary substrates are used. by using a high concentration of the nucleophile. when L- is a strong base. by use of a non-polar solvent. by none of the above. Ans: A Topic: Generalities 36. Which of the following statements is (are) true of an SN2 reaction of (R)-2-bromobutane with hydroxide ion? A) Doubling the hydroxide ion concentration would double the rate of the reaction. (Assume that all other experimental conditions are unchanged.) B) The major product would be (S)-2-butanol. C) Doubling the concentration of (R)-2-bromobutane would double the rate of the reaction. (Assume that all other experimental conditions are unchanged.) D) All of the above E) Two of the above Ans: D 177 Chapter 6 Topic: Generalities 37. SN1 reactions of the following type, Nu:- + R-X ⎯⎯⎯⎯→ R-Nu + :X- A) B) C) D) E) are favored: by the use of tertiary substrates (as opposed to primary or secondary substrates). by increasing the concentration of the nucleophile. by increasing the polarity of the solvent. by use of a weak nucleophile. by more than one of the above. Ans: E Topic: Generalities 38. SN1 reactions of the following type, Nu:- + R-X ⎯⎯⎯⎯→ R-Nu + :X- A) B) C) D) E) are favored: by the use of tertiary substrates (as opposed to primary or secondary substrates). by increasing the concentration of the nucleophile. by increasing the polarity of the solvent. by use of a strong base. by more than one of the above. Ans: A Topic: Generalities 39. A) B) C) D) E) A true statement about the transition state(s) of an SN2 reaction is: the two transition states are of unequal energy. the transition states precede and follow an unstable reaction intermediate. the single transition state represents the point of maximum free energy of the reaction. existence of this transition state implies an exothermic reaction. the transition state will always have a net charge of -1. Ans: C 178 Chapter 6 Topic: Generalities 40. A) B) C) D) E) Elimination reactions are favored over nucleophilic substitution reactions: at high temperatures. when tert-butoxide ion is used. when 3° alkyl halides are used as substrates. when nucleophiles are used which are strong bases and the substrate is a 2° alkyl halide. in all of these cases. Ans: E Topic: Carbocations 41. A) B) C) D) E) The hybridization state of the charged carbon in a carbocation is sp4 sp3 sp2 sp s Ans: C Topic: Carbocations 42. A) B) C) D) E) The p orbital of a methyl cation, CH3+, contains how many electrons? 1 2 3 4 0 Ans: E Topic: Carbocations 43. The p orbital of the charged carbon in the isopropyl cation, (CH3)2CH+, contains how many electrons? A) 1 B) 2 C) 3 D) 4 E) 0 Ans: E 179 Chapter 6 Topic: Generalities, solvent effects 44. Considering the relative solvation of reactants and the transition states of SN reactions of these reactants, predict which general type of reaction would be most favored by the use of a polar solvent. A) Y: + RX ⎯⎯⎯⎯→ RY+ + X:B) Y:- + RX ⎯⎯⎯⎯→ RY + X:C) Y: + RX+ ⎯⎯⎯⎯→ RY+ + X: D) Y:- + RX+ ⎯⎯⎯⎯→ RY + X: E) RX+ ⎯⎯⎯⎯→ R+ + X: Ans: A Topic: Generalities, solvent effects 45. Which is not a polar aprotic solvent? O A) C H3C H B) 3C C) C O CH3 N S H3C O D) CH3 C H N CH3 CH3 CH3 E) CH H3C OH Ans: E Topic: Generalities, solvent effects 46. A) B) C) D) E) Which is a polar aprotic solvent? 2-methylhexane CH3CN NH3(l) CH3CH2CH2OCH2CH2CH3 2-methyl-2-propanol Ans: E 180 Chapter 6 Topic: Generalities, nucleophiles 47. Identify the nucleophile in the following reaction. A) B) C) D) E) 2 H2O + RX Æ ROH + H3O+ + X− XH3O+ ROH H2O RX Ans: D Topic: Generalities, nucleophiles 48. Identify the nucleophile in the following reaction. A) B) C) D) E) 2 R’OH + RX Æ ROR’ + [ROH2]+ + X− X− [ROH2]+ ROR’ R’OH RX Ans: D Topic: Transition State theory 49. A) B) C) D) E) An increase in the kinetic energy of reacting molecules results in: a decrease in reaction rate. an increase in the probability factor. a decrease in the probability factor. an increase in the reaction rate. no changes. Ans: D 181 Chapter 6 Topic: Generalities, leaving group 50. Identify the leaving group in the following reaction. S−Na+ S Na+ I A) B) C) D) E) + I− C6H5SNa+ CH3CH2I C6H5SCH2CH3 IAns: E Topic: Generalities, solvent effects 51. A) B) C) D) E) Which is the weakest nucleophile in polar aprotic solvents? IBrClFAll of the above are equally strong nucleophiles, regardless of the type of solvent used Ans: A Topic: Generalities, solvent effects 52. A) B) C) D) E) Which is the weakest nucleophile in polar protic solvents? IBrClFAll of the above are equally strong nucleophiles, regardless of the type of solvent used Ans: D Topic: Generalities, leaving group 53. A) B) C) D) E) Which of the following is the poorest leaving group? H− CH3O− H2O OH− NH2− Ans: E 182 Chapter 6 Topic: Generalities, nucleophiles 54. A) B) C) D) E) Which of the following is not a nucleophile? H2O CH3ONH3 NH4+ All are nucleophiles. Ans: D Topic: Generalities, solvent effects 55. A) B) C) D) E) Which ion is the strongest nucleophile in aqueous solution? FClBrIAll of these are equally strong. Ans: D Topic: Leaving groups 56. A) B) C) D) E) Which of the following is not a good leaving group? C2H5O− Cl− I− CH3CO2− All of these are good leaving groups Ans: A Topic: Leaving groups 57. Identify the leaving group in the following reaction: CH3OH + CH3OH2 CH3OCH3 + H2O H A) B) C) D) E) CH3OH CH3OH2+ CH3OCH3 H2O None of these Ans: D 183 Chapter 6 Topic: Nucleophiles 58. Which is the strongest nucleophile? A) OHB) CH3CH2OC) D) CH3CH2OH E) H2O Ans: B Topic: Nucleophile, solvent effects 59. Which is the most reactive nucleophile in DMF (structure shown below) ? H A) B) C) D) E) O C CH3 N CH3 FClBrIThey are all equally reactive. Ans: A Topic: Nucleophile, solvent effects 60. Which of these species, acting in a protic solvent, exhibits greater nucleophilic activity than expected on the basis of its basicity? A) OHB) CH3OC) SHD) ClE) H2O Ans: C 184 Chapter 6 Topic: Nucleophilicity 61. The relative nucleophilicities of species do not necessarily parallel the relative basicities of the same species because: A) not all nucleophiles are bases, and vice versa. B) experimental measurements of sufficient accuracy are not available to make the comparisons. C) nucleophilicity is a thermodynamic matter; basicity is a matter of kinetics. D) basicity is a thermodynamic matter; nucleophilicity is a matter of kinetics. E) Actually, the relative values do parallel one another. Ans: D Topic: Nucleophiles 62. Ambident nucleophiles are ones which can react with a substrate at either of two nucleophilic sites. Which of the following is not an ambident nucleophile? .. .. 2 .. :OCH CH S: :CN: 2 2 :OH .. .. .. I A) B) C) D) E) III II .. .. :O:N::O .. .. H. . .. .. . N:O:H .. H. IV V I II III IV V Ans: B Topic: Nucleophile, solvent effects 63. A) B) C) D) E) Which ion is the strongest nucleophile in an aprotic solvent such as dimethylsulfoxide? IBrClFThese are all equal. Ans: D 185 Chapter 6 Topic: Leaving group 64. A) B) C) D) E) Which of the following is a feasible substitution reaction? CH3CH2Cl + NaBr ⎯⎯⎯⎯→ CH3CH2I + NaCl CH3CH3 + NaCN ⎯⎯⎯⎯→ CH3CH2CN + NaH CH3CH2Cl + NaOH ⎯⎯⎯⎯→ CH2=CH2 + H2O + NaCl More than one of the above None of the above Ans: A Topic: Predicting mechanism, products 65. Heating tert-butyl chloride with 1.0 M NaOH in a mixture of water and methanol would yield mainly: A) (CH3)3COH through an SN1 reaction. B) (CH3)3COCH3 through an SN1 reaction. C) (CH3)3COH through an SN2 reaction. D) (CH3)3COCH3 through an SN2 reaction. E) CH2=C(CH3)2 through an E2 reaction. Ans: E 186 Chapter 6 Topic: Free energy diagrams 66. Select the potential energy diagram that represents an exothermic (exergonic) reaction. A) B) C) D) E) I II III IV V Ans: E 187 Chapter 6 Topic: Free energy diagrams 67. Select the potential energy diagram that represents a single-step endothermic (endergonic) reaction. A) B) C) D) E) I II III IV V Ans: A 188 Chapter 6 Topic: Free energy diagrams 68. Select the potential energy diagram that represents a two-step endothermic (endergonic) reaction. A) B) C) D) E) I II III IV V Ans: B Topic: Hammond-Leffler postulate 69. The Hammond-Leffler postulate when applied to nucleophilic substitutions and elimination reactions states that: A) a negatively-charged nucleophile is stronger than its conjugate acid. B) polar aprotic solvents strongly accelerate the rate of SN2 processes. C) bimolecular nucleophilic substitutions are 2nd order kinetically. D) the transition state for an endergonic reaction step (one accompanied by an increase in free energy) resembles the product of that step. E) elimination reactions will always compete with nucleophilic substitution reactions. Ans: D 189 Chapter 6 Topic: Transition state theory 70. A) B) C) D) E) Which will be true for any actual or potential nucleophilic substitution reaction? ΔH° is positive. ΔH° is negative. ΔG‡ is positive. ΔG° is positive. ΔG° is negative. Ans: C Topic: Entropy changes 71. For the typical SN2 reaction Y- + RX ⎯⎯⎯⎯→ RY + X- A) B) C) D) E) it can be predicted that ΔS‡ will be: positive. zero. negative. either positive or negative. unpredictable as to algebraic sign. Ans: C Topic: Free energy changes 72. The reaction, CH3Cl + OH− A) B) C) D) E) H2O CH3OH + Cl− has the following thermodynamic values at 27ºC: ΔH = -75.3 kJ mol-1; ΔS = 54.4 J K-1 mol-1. What is the value of ΔG for this reaction? -73.8 kJ mol-1 -76.8 kJ mol-1 -59.0 kJ mol-1 +91.6 kJ mol-1 -91.6 kJ mol-1 Ans: E 190 Chapter 6 Topic: Activation energy 73. A) B) C) D) E) An increase in the temperature at which reaction is carried out increases: the collision frequency. the fraction of molecules with proper orientation. the fraction of molecules with energy greater than Eact. More than one of the above None of the above Ans: D Topic: Free energy diagrams 74. The difference in the bond energies of reactants and the transition state of a reaction is designated by the notation: A) ΔH° B) ΔH‡ C) ΔG° D) ΔG‡ E) ΔS‡ Ans: B Topic: Hammond-Leffler postulate 75. Which is a true statement concerning the transition state of the rate-determining step of an SN1 reaction? A) Structurally, it closely resembles the carbocation intermediate. B) Both covalent bond-breaking and bond-making are occurring. C) Formation of the transition state is an exothermic reaction. D) Necessarily, the transition state has zero charge overall. E) More than one of the above Ans: A Topic: Stereochemistry of SN/E reactions 76. Which of the following reactions proceeds with inversion of configuration at the carbon bearing the leaving group? A) SN2 B) SN1 C) E2 D) E1 E) All of these Ans: A 191 Chapter 6 Topic: Predicting mechanism, stereochemistry of SN reactions 77. Consider the substitution reaction that takes place when (R)-3-bromo-3-methylhexane is treated with methanol. Which of the following would be true? A) The reaction would take place only with inversion of configuration at the stereogenic center. B) The reaction would take place only with retention of configuration at the stereogenic center. C) The reaction would take place with racemization. D) No reaction would take place. E) The alkyl halide does not possess a stereogenic center. Ans: C Topic: Predicting mechanism, stereochemistry of SN reactions 78. Consider the substitution reaction that takes place when (R)-3-bromo-3-methylhexane is treated with sodium methoxide. Which of the following would be true? A) An SN2 reaction would take place with inversion of configuration at the stereogenic center. B) An SN1 reaction would take place with retention of configuration at the stereogenic center. C) An SN1 reaction would take place with racemization of configuration at the stereogenic center. D) An SN1 reaction would take place, accompanied by an E1 reaction, affording a complex mixture of products. E) An E2 reaction would take place, during which the stereogenic center is lost. Ans: E Topic: Predicting mechanism, stereochemistry of SN reactions 79. Consider the substitution reaction that takes place when (R)-3-iodo-3-methylheptane is treated with sodium acetate (CH3CO2Na). Which of the following would be true? A) An SN2 reaction would take place with inversion of configuration at the stereogenic center. B) An SN1 reaction would take place with retention of configuration at the stereogenic center. C) An SN1 reaction would take place with racemization of configuration at the stereogenic center. D) An SN1 reaction would take place, accompanied by an E1 reaction, affording a complex mixture of products. E) An E2 reaction would take place, during which the stereogenic center is lost. Ans: D 192 Chapter 6 Topic: Predicting products 80. Which alkyl halide, when treated with sodium ethoxide in ethanol, would afford a product mixture consisting of more than one elimination product? A) 1-bromo-3,3-dimethylpentane B) 1-bromo-2,3-dimethylpentane C) 2-bromo-3,4-dimethylpentane D) 2-bromo-3,3-dimethylpentane E) None of the above would yield more than one elimination product Ans: C Topic: Leaving groups, nucleophiles 81. A) B) C) D) E) Which SN2 reaction will occur most rapidly in a mixture of water and ethanol? I- + CH3CH2–Br ⎯⎯⎯⎯→ CH3CH2–I + BrI- + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–I + ClI- + CH3CH2–F ⎯⎯⎯⎯→ CH3CH2–I + FBr- + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–Br + ClBr- + CH3CH2–F ⎯⎯⎯⎯→ CH3CH2–Br + FAns: A Topic: Predicting mechanism, kinetics 82. Which SN2 reaction will occur most rapidly in aqueous acetone solution? Assume concentrations and temperature are the same in each instance. A) HO- + CH3-Cl ⎯⎯⎯⎯→ CH3OH + ClB) HO- + CH3CH2-Cl ⎯⎯⎯⎯→ CH3CH2OH + ClC) HO- + (CH3)2CH-Cl ⎯⎯⎯⎯→ (CH3)2CHOH + ClD) HO- + (CH3)3C-Cl ⎯⎯⎯⎯→ (CH3)3COH + ClE) HO- + (CH3)3CCH2-Cl ⎯⎯⎯⎯→ (CH3)3CCH2OH + ClAns: A Topic: Kinetics 83. A) B) C) D) E) Which alkyl halide would you expect to undergo an SN2 reaction most slowly? 1-bromohexane 1-bromo-2-methylpentane 1-bromo-3-methylpentane 1-bromo-4-methylpentane 1-bromo-2,2-dimethylbutane Ans: E 193 Chapter 6 Topic: Kinetics, nucleophilicity 84. Which SN2 reaction would take place most rapidly? H2O A) OH− + CH3Cl CH3OH + Cl− o 25 C O O B) H2O − + CH3Cl + Cl o − 25 C H3C O H3CO CH3 H 2O C) H2O + CH3Cl CH3OH2+ + Cl− 25oC H D) CH3OH O CH3OH + CH3Cl + Cl− 25oC H3C CH3 H2O E) SH− + CH3Cl CH3SH + Cl− o 25 C Ans: E Topic: Leaving groups 85. A) B) C) D) E) Which nucleophilic substitution reaction would be unlikely to occur? HO− + CH3CH2–I ⎯⎯⎯⎯→ CH3CH2–OH + I− I− + CH3CH2–H ⎯⎯⎯⎯→ CH3CH2–I + H− CH3S− + CH3–Br ⎯⎯⎯⎯→ CH3S–CH3 + Br− All of the above would be unlikely to occur None of the above would be unlikely to occur Ans: B Topic: Predicting products 86. Which nucleophilic substitution reaction would be likely to occur (although probably not in excellent yield, due to competing elimination) ? A) HO− + CH3CH2CH2CHICH3 ⎯⎯⎯⎯→ CH3 CH2CH2CHOHCH3 + I− B) Cl− + CH3CH2CH2CH2–OH ⎯⎯⎯⎯→ CH3CH2CH2CH2–Cl + OH− C) CH3S− + CH3CH2CH2–OCH3 ⎯⎯⎯⎯→ CH3S–CH2CH2CH3 + OCH3− D) All of the above are likely to occur E) None of the above are likely to occur Ans: B 194 Chapter 6 Topic: Leaving groups 87. Which alkyl halide would you expect to react most slowly when heated in aqueous solution? A) (CH3)3C-F B) (CH3)3C-Cl C) (CH3)3C-Br D) (CH3)3C-I E) They would all react at the same rate. Ans: A Topic: Nucleophilicity, leaving groups 88. Which SN2 reaction would you expect to take place most rapidly? Assume that the concentrations of the reactants and the temperature are the same in each instance: − CH3SCH3 + I − A) CH3S + CH3I H B) CH3SH + CH3I − C) CH3O D) + CH3I CH3OH + CH3I − E) CH3S + CH3Cl Ans: A S H3C CH3 CH3OCH3 + + I− I − H O H3C CH3 CH3SCH3 + + I− Cl − Topic: Leaving groups 89. A) B) C) D) E) Which nucleophilic substitution reaction is not likely to occur? I− + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–I + Cl− I− + CH3CH2–Br ⎯⎯⎯⎯→ CH3CH2–I + Br− I− + CH3CH2–OH ⎯⎯⎯⎯→ CH3CH2–I + OH− CH3O− + CH3CH2–Br ⎯⎯⎯⎯→ CH3CH2–OCH3 + Br− OH− + CH3CH2–Cl ⎯⎯⎯⎯→ CH3CH2–OH + Cl− Ans: C 195 Chapter 6 Topic: Leaving groups 90. Which of the following would be most reactive in an SN2 reaction? A) Br B) Br C) Br D) Br E) Br Ans: D Topic: Steric hindrance 91. Which alkyl chloride, though primary, is essentially unreactive in SN2 reactions? Cl A) B) Cl C) Cl Cl D) E) Cl Ans: E 196 Chapter 6 Topic: Kinetics 92. Which alkyl halide would be most reactive in an SN1 reaction? Br Br Br I II III Br Br IV A) B) C) D) E) V I II III IV V Ans: D Topic: Predicting mechanisms 93. Which of these compounds would give the largest E2/SN2 product ratio on reaction with sodium ethoxide in ethanol at 55°C? Cl A) B) Cl C) Cl D) Cl E) Cl Ans: D 197 Chapter 6 Topic: Multistep synthesis, acid-base reactions, SN2 94. What final product is likely to be obtained through the following series of reactions? NaNH2 Br A B NH3(l) Ans: Topic: Multistep synthesis, acid-base reactions, SN2, hydrogenation 95. What final product is likely to be obtained through the following series of reactions? NaNH2 Cl A NH3(l) B excess H2 C Ni Ans: Topic: Multistep synthesis, acid-base reactions, SN2 96. What final product is likely to be obtained through the following series of reactions? NaH Cl OH B A diethylether Ans: O SHORT ANSWER QUESTIONS Topic: Bond length, bond strength, leaving groups 97. As we go down Group 7A of the periodic table, the size of the halogen atom increases; accordingly, the carbon-halogen bond length gets _______________ and the bond strength gets _______________. Ans: longer; weaker 198 Chapter 6 Topic: Transition state theory 98. In the SN2 reaction, the unstable arrangement of atoms in which both the nucleophile and the leaving group are partially bonded to the same carbon atom is called the ______________________. Ans: transition state Topic: Solvolysis 99. A reaction in which the nucleophile is a molecule of the solvent is referred to as a ______________ reaction. Ans: solvolysis Topic: Carbocation stability 100. The substitution mechanism whose rate depends primarily on the relative stability of the intermediate carbocation is the _________. Ans: SN1 Topic: Steric hindrance 101. The substitution mechanism whose rate depends primarily on the degree of steric hindrance around the leaving group is the _________. Ans: SN2 Topic: Carbocation stability 102. The stabilizing effect of alkyl substituents on carbocations can be explained through _____________________. Ans: hyperconjugation Topic: Activation energy, kinetics 103. Increasing the concentration of either of the reactants of an SN2 reaction increases the rate of the reaction. The primary reason for this is that increasing the concentration increases ________________________. Ans: the frequency of collisions between reactant species, thereby statistically increasing the chance encounters between species having the requisite Eactivation Topic: Activation energy, transition state theory 104. In order for colliding species to react, they must _____________ and ____________. Ans: have energy equal/greater than the activation energy, approach with the proper orientation. 199 Chapter 6 Topic: Free energy diagrams 105. Draw the potential energy diagram that represents an exothermic reaction between a tertiary alkyl halide and methanol. Briefly explain your rationale. Ans: The reaction is likely to occur via an SN1 mechanism. The first step is the ratedetermining step, leading to the formation of a tertiary carbocation. The second step is a fast step, where the methanol oxygen acts as a nucleophile, attaching to the positively charged carbon, forming a protonated ether; the last step is a fast loss of a proton to form the (uncharged) ether product. Energy time Topic: Predicting reaction mechanisms 106. Give a detailed reaction mechanism for the reaction expected to occur when 2-bromo-2methylpentane is heated with sodium methoxide. Draw clear structural formulas of all relevant species and use curved arrows to represent electron flow. Also indicate which step is likely to be rate-determining. Ans: The reaction is likely to occur via an E2 mechanism. The first step is the ratedetermining step, leading to the formation of a tertiary carbocation, followed by base promoted elimination to afford 2 different alkene products. .. : Br : H slow .. [ - Br: .. ] H 200 .. :OCH .. 3 fast Chapter 6 Topic: SN1 kinetics 107. Typically, increasing the concentration of the nucleophile of an SN1 reaction has no impact on the rate of the reaction. The reason for this is that ________________________. Ans: An SN1 reaction is a multi-step process; the overall reaction rate is determined by the rate of formation of the carbocation intermediate. Since the nucleophile is not involved in the rate-determining step, changes in its concentration typically have no impact on the rate of reaction. Topic: Nucleophilicity, solvent effects 108. The relative nucleophilicity of the halide ions in polar aprotic solvents is observed to be markedly different from that in protic solvents. Explain briefly. Ans: The smaller, more highly electronegative fluoride ion is more effectively solvated in a protic solvent and is therefore a weaker nucleophile compared to the larger, less electronegative and more polarizable iodide ion. The situation is reversed in aprotic solvents, where the nucleophile is essentially unsolvated; thus, the nucleophilicity parallels the basicity of the halide ions, so that the fluoride ion is the strongest nucleophile of the halide ions Topic: Acid-base reactions, intramolecular SN2 109. When 5-bromo-1-pentanol is treated with sodium hydride in diethyl ether, the product is analyzed to be C5H10O. Propose a likely structure for this product, suggesting a reasonable mechanistic pathway for its formation. Ans: The alcohol is likely to be first deprotonated by the strong base, generating an alkoxide ion, which can then undergo intramolecular SN2 reaction to afford the observed product, a cyclic ether. Cl .. OH .. NaH −H2 Cl 201 .. + O .. : Na O NaCl Chapter 7 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. A correct IUPAC name for the following compound is: A) B) C) D) E) 3,3,5-trimethyl-2-hexene 3-isobutyl-3-isopropyl-2-propene 3-isobutyl-4-methyl-2-pentene 3-(1-methylethyl)-5-methyl-2-hexene None of the above Ans: D Topic: Nomenclature 2. The correct IUPAC name for the following compound is: Br A) B) C) D) E) 2-Bromo-4-methylenehexane 2-(2-Bromopropyl)-1-butene 4-Bromo-2-ethyl-1-pentene 2-Bromo-4-ethyl-1-pentene 2-Bromo-4-ethyl-4-pentene Ans: C Topic: Nomenclature 3. Give the IUPAC name for A) B) C) D) E) 3-Methyl-4-hexyne 4-Methyl-2-hexyne 2-Ethyl-3-pentyne 4-Ethyl-2-pentyne 3-Methyl-2-hexyne Ans: B 202 Chapter 7 Topic: Nomenclature 4. The correct IUPAC name for the following compound is: A) B) C) D) E) 4,5-Dimethyl-3-propyl-2-hexene 4,5-Dimethyl-3-propyl-1-hexene 3-(2,3-Dimethylpropyl)-1-hexene 2,3-Dimethyl-4-isopropyl-5-hexene 2,3-Dimethyl-4-propyl-5-hexene Ans: B Topic: Nomenclature 5. Select the structure of 4–ethyl-2,3-dimethyl-2-heptene. A) B) C) D) E) Ans: B 203 Chapter 7 Topic: Nomenclature 6. Select the structure for cis-3-methyl-6-vinylcyclohexene. I II IV A) B) C) D) E) III V I II III IV V Ans: B Topic: Nomenclature 7. The correct IUPAC name for the following compound is: Cl Br A) B) C) D) E) (E)-2-Bromo-3-chloro-5-methyl-2-hexene (E)-2-Bromo-3-chloro-5-methyl-3-hexene (Z)-2-Bromo-3-chloro-5-methyl-3-hexene (Z)-2-Bromo-3-chloro-5-methyl-2-hexene (E)-2-Methyl-5-bromo-4-chloro-4-hexene Ans: A 204 Chapter 7 Topic: Nomenclature 8. A) B) C) D) E) The IUPAC name for diisobutylacetylene is 2,7-Dimethyl-4-octene 2,7-Dimethyl-4-octyne 3,6-Dimethyl-4-octyne 2,5-Diethyl-3-hexyne 2,2,5,5-Tetramethyl-3-hexyne Ans: B Topic: Carbocation Stability, Rearrangement 9. Which of the following carbocations would NOT be likely to undergo rearrangement? A) CH3CHCHCH3 CH3 CH3 B) CH3CHCCH3 C) CH3 CH3 CH3CCH2CH3 D) CH3 CH3CHCH2 CH3 E) CH3CCHCH2CH3 CH3 Ans: C 205 Chapter 7 Topic: Carbocation stability 10. Which alcohol would initially produce the most stable carbocation when treated with concentrated H2SO4? A) OH B) OH C) OH D) HO E) HO Ans: A Topic: Carbocation Stability, Rearrangement 11. A) B) C) D) E) Which statement(s) is (are) true of acid-catalyzed alcohol dehydrations? Protonation of the alcohol is a fast step. Formation of a carbocation from the protonated alcohol is a slow step. Rearrangements of less stable carbocations to more stable carbocations are common. Loss of a proton by the carbocation is a fast step. All of the above Ans: E Topic: Carbocation Stability, Rearrangement 12. Carbocations are frequent intermediates in acidic reactions of alkenes, alcohols, etc. What do carbocations usually do? They may: A) rearrange to a more stable carbocation. B) lose a proton to form an alkene. C) combine with a nucleophile. D) react with an alkene to form a larger carbocation. E) do all of the above. Ans: E 206 Chapter 7 Topic: Carbocation Stability, Rearrangement 13. Neopentyl alcohol, (CH3)3CCH2OH, cannot be dehydrated to an alkene without rearrangement. What is the chief product of dehydration? I II IV A) B) C) D) E) III V I II III IV V Ans: B Topic: Carbocation Stability, Rearrangement 14. A) B) C) D) E) Rearrangements are likely to occur in which of the following reaction types? SN1 reactions SN2 reactions E1 reactions E2 reactions Both SN1 and E1 reactions Ans: E 207 Chapter 7 Topic: Alkene Synthesis, Reaction Mechanisms 15. Which compound listed below would you expect to be the major product when 2bromo-2-methylbutane is refluxed with KOH/ethanol? A) OH B) O C) D) E) Ans: D Topic: Alkene Synthesis, Reaction Mechanisms 16. Which product(s) would be produced by acid-catalyzed dehydration of 2-methyl-2pentanol? A) B) and C) and D) E) O Ans: B 208 Chapter 7 Topic: Alkene Synthesis, Reaction Mechanisms 17. Which product (or products) would be formed in appreciable amount(s) when trans-1bromo-2-methylcyclohexane undergoes dehydrohalogenation upon treatment with sodium ethoxide in ethanol? I A) B) C) D) E) II III IV I II III IV More than one of these Ans: B Topic: Alkene Reactions, Reaction Mechanisms 18. Which would be the major product of the following reaction? D2, Ni ? D CH3 D D CH3 DD H CH3 H D I H II III CH3 DH D D CH3 D H IV A) B) C) D) E) V I II III IV V Ans: A 209 Chapter 7 Topic: Alkene Synthesis, Reaction Mechanisms 19. What is the major product of the reaction, (CH3)3COK ? (CH3)3COH heat Br A) B) C) D) E) (CH3)2C=C(CH3)2 (CH3)3C–CH=CH2 (CH3)2C=CHCH3 (CH3)2C=CHCH2CH3 None of these Ans: B Topic: Alkene Synthesis, Reaction Mechanisms 20. Which compound would be the major product? Br (CH3)3COK ? (CH3)3COH heat O A) B) C) OH D) E) Ans: E 210 Chapter 7 Topic: Alkene Synthesis, Reaction Mechanisms, Carbocation Rearrangements 21. What will be the major product of the following reaction? 85% H3PO4 ? heat OH A) B) C) D) O E) Ans: A 211 Chapter 7 Topic: Alkene Synthesis, Reaction Mechanisms, Carbocation Rearrangements 22. Which alkene would you expect to be the major product of the following dehydration? H2SO4 ? heat OH I IV A) B) C) D) E) III II V I II III IV V Ans: C 212 Chapter 7 Topic: Alkyne Synthesis, Catalytic hydrogenation 23. The structure of the product, C, of the following sequence of reactions would be: NaNH2 A CH3CH2Br NH3(l) B H2 Ni2B [P-2] A) B) C) Br D) E) Ans: A Topic: Dissolving Metal Reduction; trans-hydrogenation 24. The structure of the product obtained from 2-butyne and Li/C2H5NH2 is: A) B) C) HN D) NH E) Ans: A 213 C Chapter 7 Topic: Catalytic hydrogenation 25. Which alkene would yield 3-methylpentane when subjected to catalytic hydrogenation? A) B) C) D) E) Ans: B Topic: Alkyne Synthesis 26. A) B) C) D) E) Which reaction would yield 2-butyne? CH3C≡C:− Na+ + CH3Br ⎯⎯⎯⎯→ CH3CH2Br + HC≡C:− Na+ ⎯⎯⎯⎯→ CH3:− Na+ + HC≡CCH3 ⎯⎯⎯⎯→ More than one of these None of these Ans: A Topic: Alkyne Synthesis 27. Which of the following methods could be used to synthesize 4,4-dimethyl-2-hexyne? CH3 A) C2H5 C C C: Na CH3 H3C I CH3 B) H3C C C: Na C2H5 C Br CH3 C) NaNH2 ( excess) Br Br NH3 (l) D) More than one of these E) None of these Ans: D 214 Chapter 7 Topic: Alkene Synthesis 28. Your task is to convert 2-bromobutane to 1-butene in highest yield. Which reagents would you use? A) KOH/H2O B) KOH/CH3OH C) CH3ONa/CH3OH D) CH3CH2ONa/CH3CH2OH E) (CH3)3COK/(CH3)3COH Ans: E Topic: Alkene Synthesis, Nomenclature 29. Which of the following reactions would yield 3,3-dimethyl-1-butene in a reasonable percentage yield (i.e., greater than 50%)? A) H2SO4 heat OH B) (CH3)3COK, (CH3)3COH heat Br C) i) 3 NaNH2, mineral oil, heat Br Br ii) H3O+ D) All of these E) Answers B) and C) only Ans: B 215 Chapter 7 Topic: Alkene Synthesis, Reaction Mechanisms 30. Which compound(s) would be produced by the following reaction? CH3 CH3CH2OH Br H3C 55oC ? H OCH2CH3 CH3 OCH2CH3 H3C H A) B) C) D) E) I I II III More than one of the above All of the above Ans: E CH3 CH3 H3C CH3 H II III Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms 31. Dehydrohalogenation of tert-pentyl bromide will produce 2-methyl-1-butene as the chief product when: A) CH3COONa is employed as the base. B) KOH/C2H5OH is employed as the base. C) CH3CH2ONa/CH3CH2OH is employed as the base. D) (CH3)3COK/(CH3)3COH is employed as the base. E) any base is used, as long as the temperature is sufficiently high. Ans: D Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms 32. A) B) C) D) E) Which is not a satisfactory procedure for the synthesis of 3-methyl-1-butene? (CH3)2CHCΗΟΗCH3 + conc. H2SO4 (CH3)2CHC≡CH + Li/liq.NH3 (CH3)2CHCH2CH2Br + CH3ONa/CH3OH (CH3)2CHCHBrCH3 + (CH3)3COK/(CH3)3COH (CH3)2CHC≡CH + H2/Ni2B (P-2) Ans: A 216 Chapter 7 Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms 33. A) B) C) D) E) Which of these is the most satisfactory method for the preparation of cis-2-pentene? CH3CHBrCH2CH2CH3 + (CH3)3COK/(CH3)3COH CH3C≡CCH2CH3 + H2,Pt CH3C≡CCH2CH3 + H2, Ni2B (P-2) CH3C≡CCH2CH3 + Li/liq. NH3 CH3CH2CHBrCH2CH3 + CH3CH2ONa/CH3CH2OH Ans: C Topic: Alkyne Reduction, Nomenclature, Reaction Mechanisms 34. A) B) C) D) E) Which of the following reductions of an alkyne is NOT correct? 2-Pentyne + 2H2/Pt Æ pentane 2-Pentyne + H2/Ni2B Æ Z-2-Pentene 2-Pentyne + Li/NH3(l) Æ Z-2-Pentene All of the above are correct. None of the above is correct. Ans: C Topic: Alkene Synthesis, Nomenclature, Reaction Mechanisms 35. Which of the following reactions would yield 2-pentyne? I A) NaNH2 (1 mol) NaNH2 B) Br (1 mol) C) Br Zn CH3CO2H Br HA heat D) OH E) Br NaOC2H5 C2H5OH Ans: B 217 Chapter 7 Topic: Alkyne Synthesis, Nomenclature, Reaction Mechanisms 36. Which reaction would not be a method for preparing 5-methyl-1-hexyne? A) 1) NaNH2 (2 mol), liq NH3 Br 2) NH4+ B) HC CNa + Cl C) Li D) + HC CH 1) NaNH2 (3 mol), liq NH3 Br Br Br E) Br 2) NH4+ 1) NaNH2 (3 mol), liq NH3 2) NH4+ Ans: C Topic: Index of Hydrogen Deficiency 37. A) B) C) D) E) Compute the index of hydrogen deficiency for the molecule C10H8. 3 4 5 6 7 Ans: E 218 Chapter 7 Topic: Index of Hydrogen Deficiency 38. Which compound has an index of hydrogen deficiency equal to three? I II III IV A) B) C) D) E) V I, III IV, V V II II, V Ans: E Topic: Index of Hydrogen Deficiency, Nomenclature 39. A) B) C) D) E) What is the index of hydrogen deficiency of bicyclo[2.2.2]octane? 1 2 3 4 5 Ans: B Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 40. Which is a possible structure for a compound with an index of hydrogen deficiency equal to 3 and which absorbs one molar equivalent of hydrogen when treated with hydrogen and a platinum catalyst? A) B) C) D) E) I I II III IV V Ans: C II III IV 219 V Chapter 7 Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 41. Upon catalytic hydrogenation, a compound C6H6 absorbs four moles of hydrogen. Select a structure for C6H6. I A) B) C) D) E) II III IV V I, II III II, III IV, V I, IV, V Ans: D Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 42. A compound, C6H10, which reacts with 2 mol of hydrogen over a platinum catalyst and which shows an IR absorption band at approximately 3300 cm-1 could be: I II IV A) B) C) D) E) III V I II III IV V Ans: C 220 Chapter 7 Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 43. On hydrogenation, a compound C9H12 absorbs 2 mol of hydrogen. Which of the following is a possible structure for the compound? I IV A) B) C) D) E) III II V I II III IV V Ans: D Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 44. A compound with the formula C10H14 reacts with excess hydrogen and a catalyst to yield a compound with the formula C10H18. The compound could have: A) one ring and three double bonds. B) two rings and two double bonds. C) two rings and a triple bond. D) no rings and two double bonds. E) More than one of the above Ans: E Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 45. A) B) C) D) E) X (C8H14) H2, Pt 25oC Given: One can conclude that X has: no rings and no double bonds. no rings and one double bond. one ring and one double bond. two rings and no double bonds. one triple bond. Ans: C Y (C8H16) 221 Chapter 7 Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 46. What is the structure of a compound with formula C6H10 which has IR absorption at approximately 3300 cm-1 and which can be catalytically reduced with hydrogen to 2methylpentane? A) B) C) D) E) Ans: D Topic: Index of Hydrogen Deficiency, Catalytic Hydrogenation 47. A compound X with the formula C7H10 undergoes catalytic hydrogenation to produce a compound Y with the formula C7H14. What might be true of X? A) X might have one triple bond and one ring. B) X might have two double bonds and one ring. C) X might have one double bond and two rings. D) X might have one double bond and one triple bond. E) More than one of the above Ans: E Topic: Alkene Stability, Heats of Hydrogenation and Combustion 48. Which reaction would you expect to liberate the least heat? A) + 9O2 6CO2 + 6H2O B) C) + 9O2 6CO2 + 6H2O + 9O2 6CO2 + 6H2O + 9O2 D) E) + 9O2 6CO2 + 6H2O 6CO2 + 6H2O Ans: C 222 Chapter 7 Topic: Alkene Stability, Heats of Hydrogenation and Combustion 49. One mol of each of the following alkenes is subjected to complete combustion. Which would you expect to liberate the LEAST heat? A) 1-Pentene B) 2-Pentene C) 2-Methyl-1-butene D) 2-Methyl-2-butene E) 3-Methyl-1-butene Ans: D Topic: Alkene Stability, Heats of Hydrogenation and Combustion 50. Which molecule would have the lowest heat of hydrogenation? A) B) C) D) E) I I II III IV V Ans: A II III IV V Topic: Alkene Stability, Heats of Hydrogenation and Combustion, Nomenclature 51. One mole of each of the following alkenes is subjected to complete combustion. Which would you expect to liberate the most heat? A) 1-Pentene B) cis-2-Pentene C) 2-Methyl-1-butene D) 2-Methyl-2-butene E) trans-2-Pentene Ans: A 223 Chapter 7 Topic: Alkene Stability, Heats of Hydrogenation and Combustion 52. Which reaction would you expect to liberate the most heat? A) + 9O2 6CO2 + 6H2O B) C) + 9O2 6CO2 + 6H2O + 9O2 6CO2 + 6H2O + 9O2 D) E) + 9O2 6CO2 + 6H2O 6CO2 + 6H2O Ans: C Topic: Alkene Stability, Heats of Hydrogenation and Combustion 53. Heats of hydrogenation data would be useful in comparing the relative stabilities of which of the following substances? I II III IV V I, II, III III, IV I, II, V Heats of hydrogenation data would not be a useful way to compare relative stabilities of any of the substances E) All of the above substances could effectively be compared using heats of hydrogenation data Ans: C A) B) C) D) Topic: Alkene Stability, Heats of Hydrogenation and Combustion 54. Which alkene would liberate the most heat per mole when subjected to complete combustion? A) B) C) D) E) Ans: A 224 Chapter 7 Topic: Alkene Stability, Heats of Hydrogenation and Combustion 55. Which alkene would liberate the most heat per mole when subjected to catalytic hydrogenation? A) B) C) D) E) Ans: A Topic: Alkene Stability, Heats of Hydrogenation and Combustion 56. One mole of each of the following alkenes is subjected to complete combustion. Which would liberate the least heat? I A) B) C) D) E) II III IV V I II III IV V Ans: D Topic: Alkene Stability, Heats of Hydrogenation and Combustion 57. Which alkene is most stable? I A) B) C) D) E) II III IV I II III IV V Ans: A 225 V Chapter 7 Topic: Alkene Stability, Heats of Hydrogenation and Combustion 58. Concerning the relative stabilities of alkenes, which is an untrue statement? A) Unless hydrogenation of the alkenes gives the same alkane, heats of hydrogenation cannot be used to measure their relative stabilities. B) In general, the greater the number of alkyl groups attached to the carbon atoms of the double bond, the greater the stability of the alkene. C) The greater the quantity of heat liberated on combustion or hydrogenation of an alkene, the greater its energy content. D) trans-Cycloalkenes are always more stable than the cis-isomers. E) Heats of combustion can be used to measure the relative stabilities of isomeric alkenes, even though their hydrogenation products are not identical. Ans: D Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry 59. A) B) C) D) E) Which of the following correctly lists the compounds in order of decreasing acidity? H2O > HC≡CH > NH3 > CH3CH3 HC≡CH > H2O > NH3 > CH3CH3 CH3CH3 > HC≡CH > NH3 > H2O CH3CH3 > HC≡CH > H2O > NH3 H2O > NH3 > HC≡CH > CH3CH3 Ans: A Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry 60. A) B) C) D) E) Select the strongest base. OH− RC≡C− NH2− CH2=CH− CH3CH2− Ans: E Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry Which ion is the weakest base? CH3CH2: − CH2=CH: − HC≡C: − .. − NH2 .. E) OH − .. Ans: E .. 61. A) B) C) D) .. 226 Chapter 7 Topic: Relative Acidity of Alkenes, Alkynes; Acid-Base Chemistry 62. In the following hydrocarbon, which hydrogen would have the smallest value for pKa? CH3CH2CH=CHCH2CH2C≡CH A) CH3CH2CH=CHCH2CH2C CH B) CH3CH2CH=CHCH2CH2C CH C) CH3CH2CH=CHCH2CH2C CH D) CH3CH2CH=CHCH2CH2C CH E) CH3CH2CH=CHCH2CH2C CH Ans: E Topic: Relative Acidity of Alkenes, Alkynes; Bond Lengths 63. Which of the following statements is true when ethane, ethene and acetylene are compared with one another? A) Acetylene is the weakest acid and has the longest C-H bond length. B) Acetylene is the strongest acid and has the shortest C-H bond length. C) Ethane is the strongest acid and has the longest C-H bond length. D) Ethene is the strongest acid and has the shortest C-H bond length. E) Ethene is the weakest acid and has the longest C-H bond length. Ans: B 227 Chapter 7 Topic: Alkene Synthesis; Alcohol Dehydration 64. Which one of the following alcohols would dehydrate most rapidly when treated with sulfuric acid? OH OH I OH II III OH OH IV A) B) C) D) E) V I II III IV V Ans: B Topic: Alkene Synthesis; Alcohol Dehydration 65. Which mechanistic step in the acid-catalyzed dehydration of 3,3-dimethyl-2-butanol is the rate determining step? A) Step 1: + H3O+ + H2O OH2+ OH B) Step 2: + H2O OH2+ C) Step 3: D) Step 4a: + H2O + H3O+ + H 2O + H3O E) Step 4b: Ans: B 228 + Chapter 7 Topic: Alkene Synthesis; Alcohol Dehydration 66. Which alcohol would be most easily dehydrated? CH3 A) CH3CH2CCH2CH3 OH CH3 B) CH3CH2CHCHCH3 OH CH3 C) CH3CH2CHCH2CH2OH CH3 D) HOCH2CHCH2CH2CH3 CH2OH E) CH3CH2CHCH2CH3 Ans: A Topic: Alkene Synthesis; Alcohol Dehydration 67. Which alcohol would be most easily dehydrated? OH OH I OH II III OH OH IV A) B) C) D) E) V I II III IV V Ans: B 229 Chapter 7 Topic: Alkene Structure; Stereochemistry 68. What is the simplest alkene, i.e., the one with the smallest molecular weight, which can exhibit optical activity? A) 3-methyl-1-pentene B) 3-methyl-2-pentene C) 4-methyl-1-pentene D) 3-methyl-1-butene E) 4-methyl-2-hexene Ans: A Topic: Alkene Structure; Stereochemistry 69. Determine the total number of stereoisomers which correspond to this general structure: Cl CH3CHCHCH=CHCH3 CH3 A) B) C) D) E) 4 6 8 10 12 Ans: C Topic: Alkene Structure; Stereochemistry 70. A) B) C) D) E) Which can exist as cis-trans isomers? 1-Pentene 3-Hexene Cyclopentene 2-Methyl-2-butene 3-Ethyl-2-pentene Ans: B Topic: Alkene Structure; Stereochemistry 71. A) B) C) D) E) For which of the following is cis-trans isomerism impossible? 2-Hexene 3-Methyl-2-pentene 3-Hexene 2-Methyl-2-butene 2-Pentene Ans: D 230 Chapter 7 Topic: Alkene Structure; Stereochemistry 72. A) B) C) D) E) Which of the following compounds can exhibit cis-trans isomerism? 1-Pentene 2-Pentene 2-Methyl-2-pentene 3-Methyl-1-pentene 1-Hexene Ans: B Topic: Alkene Structure; Stereochemistry 73. Which of the following compounds can exhibit cis-trans isomerism? I. 1-Pentene II. 2-Pentene III. 2-Methyl-2-pentene IV. 1,2-Dibromoethene A) B) C) D) E) V. 1,1-Dichloroethene II, III, IV I, III, V II, IV II, III None of these Ans: C Topic: Alkene Structure; Stereochemistry 74. A) B) C) D) E) What is the total number of pentene isomers, including stereoisomers? 2 3 4 5 6 Ans: E 231 Chapter 7 Topic: Nomenclature; Stereochemistry 75. Cis-trans alkenes are often distinguished from each other by examining the spatial orientation of identical groups relative to the double bond. While this often also corresponds to (Z) and (E) descriptions, sometimes it does not. For which of the following alkenes does cis- not equal (Z) or trans not equal (E)? O Cl A) B) C) D) E) Br Cl I Cl I Br II Br F III F IV OH Cl V I II III IV V Ans: C Topic: Nomenclature; Stereochemistry 76. The most specific term used to designate the relationship of cis-3-hexene to trans-3hexene is: A) stereoisomers. B) enantiomers. C) diastereomers. D) constitutional isomers. E) conformational isomers. Ans: C Topic: Nomenclature; Stereochemistry 77. A) B) C) D) E) How many stereoisomers can be predicted for 4–ethyl-2,3-dimethyl-2-heptene? 1 2 3 4 None of the above Ans: B 232 Chapter 7 Topic: General Information, Bonding 78. A) B) C) D) E) How many sigma bonds are there in CH2=CH–C≡CH? 6 7 8 9 10 Ans: B Topic: General Information, Bonding 79. A) B) C) D) E) What characteristic(s) of alkynes would make it difficult to prepare cyclohexyne? The requirement for linearity at the triple bond center The large electron density between carbons of a triple bond The short carbon-carbon triple bond length The need that the carbon-carbon triple bond be internal in the chain All of these Ans: A Topic: General Information, Nomenclature 80. The ambiguous name "methylcyclohexene" does not differentiate among this number of compounds (ignoring stereoisomers): A) 2 B) 3 C) 4 D) 5 E) 6 Ans: B Topic: Alkene Synthesis 81. Zaitsev's rule states that: A) In electrophilic addition of an unsymmetrical reagent to an unsymmetrical alkene, the more positive portion of the reagent will become attached to the carbon of the double bond bearing the greater number of hydrogen atoms. B) An equatorial substituent in cyclohexane results in a more stable conformation than if that substituent were axial. C) E2 reactions occur only if the β-hydrogen and leaving group can assume an antiperiplanar arrangement. D) When a reaction forms an alkene, and several possibilities exist, the more (or most) stable isomer is the one which predominates. E) The order of reactivity of alcohols in dehydration reactions is 3º > 2º > 1º. Ans: D 233 Chapter 7 Topic: Alkene Synthesis 82. Regarding the use of potassium tert-butoxide as a base in E2 reactions, it is incorrect to state that: A) this base is more effective than ethoxide ion, because it (KO-t-Bu) is the more basic of the two. B) it tends to give the anti-Zaitsev, i.e., Hofmann, product. C) it is more reactive in dimethyl sulfoxide than it is in tert-butyl alcohol. D) it favors E2 reactions over competing SN2 reactions. E) it will form, predominantly, the more stable alkene. Ans: E Topic: General Information 83. When an elimination reaction gives the most stable alkene as the major product, we say that the elimination follows ________________'s rule. Ans: Zaitsev Topic: General Information 84. When an elimination reaction gives the less substituted alkene as the major product, we say that the elimination follows ________________'s rule. Ans: Hofmann Topic: General Information 85. In a dehydration reaction, the leaving group is _______________. Ans: a molecule of water Topic: General Information 86. In hydrogenation reactions, both hydrogen atoms add to the pi system from the same face of the molecule. This is an example of a(n) _________ addition. Ans: syn Topic: General Information 87. Syn hydrogenation of an alkyne will produce a _________ alkene. Ans: Cis / Z Topic: General Information 88. Dehydration of alcohols requires a __________________ catalyst. Ans: strong acid 234 Chapter 7 Topic: General Information 89. Carbocations have three options available for further reaction. These options include reaction with a nucleophile, loss of a beta proton to give an alkene, and ________________. Ans: rearrangement Topic: General Information 90. Alkynes can be produced from either __________________ or _________________ dihalides. Ans: vicinal/geminal Topic: General Information 91. Conversion of alkynes to E-alkenes (trans-alkenes) can be accomplished via a __________________ reaction. Ans: dissolving metal reduction Topic: Nomenclature, Bonding 92. The number of (s-sp2) bonds in a molecule of 2,3-dimethyl-2,4-heptadiene is _____. Ans: two Topic: Alkene Hydrogenation 93. How will you prepare cis-1,2-dimethylcyclohexane from 1,2-dimethylcyclohexene? Ans: Catalytic hydrogenation with H2, Ni (or Pt/Pd) H2, Ni Topic: Alkyne Reduction 94. How will you prepare trans-2-heptene from 2-heptyne? Ans: Dissolving metal reduction with metallic Na in NH3(l). Na, NH3 (l) 235 Chapter 7 SHORT EXPLANATION / STRUCTURE DRAWING QUESTIONS Topic: Nomenclature, Stereochemistry 95. Draw the structures of all stereoisomers of 2-chloro-4-methyl-3-hexene, clearly showing all stereochemical details, using appropriate 3-D representations (dash-wedge, etc.) as relevant. 2-chloro-4-methyl-3-hexene Ans: Cl H H (2R, 3E) Cl Cl (2S, 3E) H H (2R, 3Z) Cl (2S, 3Z) Topic: Alkene Nomenclature, Relative Stability 96. The ambiguous name dimethylcyclopentene does not clearly distinguish between several structures. a) Draw the structures of all constitutional isomers corresponding to this name. b) Indicate which of these is likely to be the most stable, i.e, have the smallest heat of combustion, justifying your rationale briefly. c) Which of these structures represents an achiral molecule? Ans: a) dimethylcyclopentene I II III IV V VI b) Structure I is likely to be the most stable, because it is a tetra-substituted alkene: II, IV and V are tri-substituted; III and VI are di-substituted. c) Structure I is achiral 236 Chapter 7 Topic: Alkyne Synthesis, Acid-Base reactions 97. Complete the following reaction sequence, providing a brief rationale for your answer. O i) PCl5 ? ii) 3 NaNH2, mineral oil, heat iii) H3O+ Ans: O Cl : Na H3O+ 3 NaNH2, mineral oil, heat (-2HCl) II III I Reaction with PCl5 would afford a geminal dihalide I, which would undergo E2 elimination when heated, losing 2 moles of HCl to afford the alkyne III. However, since III is a terminal alkyne, it has a hydrogen atom that is labile in presence of NaNH2; hence, an extra mole equivalent of the base is required to ensure complete reaction and convert all of the initially formed III into the sodium alkynide intermediate, II; this, upon acidification, affords the final alkyne product III. PCl5 Cl Topic: Alkyne Synthesis, Alkyne Hydrogenation 98. Complete the following reaction, giving structural details of all intermediates as well as the final product. ? : Ans: 1) NaNH2, NH3 (l) 2) CH3CH2CH2Br 3) H2, Lindlar catalyst NaNH2 NH3 (l) Na CH3CH2CH2Br H2 Lindlar catalyst 237 Chapter 7 Topic: Carbocation Stability, Rearrangement 99. What “new”, more stable, carbocation(s) may be formed when the following carbocation undergoes spontaneous rearrangement? Ans: Topic: Nomenclature, Multistep Synthesis 100. Propose a two-step synthetic strategy for the synthesis of 2-methylhexane from 5methyl-2-hexanol. OH Ans: H2 H3O+ + Ni heat Step 1: Acid-catalyzed dehydration of 5-methyl-2-hexanol to yield an isomeric mixture of 5-methyl-1-hexene and 5-methyl-2-hexene Step 2: Catalytic hydrogenation of the double bond with H2, Ni to yield the desired 2methylhexane Topic: Nomenclature, Multistep Synthesis 101. Propose a reasonable synthetic strategy for the synthesis of trans-6-methyl-3-heptene from 4-methyl-1-pentyne. + Ans: Na : NaNH2 CH3CH2Br NH3 (l) Li, NH3(l) Step 1: Add NaNH2/NH3(l) to selectively deprotonate the alkyne hydrogen. Step 2: Add ethyl iodide to give 6-methyl-3-pentyne by an SN2 process. Step 3: Add Na(s)/NH3(l) to give the desired trans-alkene by dissolving metal reduction. 238 Chapter 7 Topic: Carbocation Rearrangement, Alkene Synthesis, Dehydration Mechanism 102. Provide a mechanistic explanation for the formation of the observed products in the following reaction. H3O+ OH heat Ans: H OH2+ :O H rearrangement : OH2+ :O H H H 2) : OH : : : 1) [-H2O] H : 3) :O H :O H H H 239 Chapter 7 Topic: Nomenclature, Index of Hydrogen Deficiency, IR Spectroscopy, Catalytic Hydrogenation 103. The IR spectrum of an unknown substance Q, C9H16, is found to have distinct peaks at 3310 cm-1 and 2140 cm-1. Treatment of Q with excess H2 in presence of Raney Ni affords nearly quantitative yields of 2,3-dimethylheptane. Propose a reasonable structure for Q, based on the above information, briefly explaining your rationale. Also give its IUPAC name. Ans: excess H2 Ni IR: 2140, 3310 cm-1 2,3-dimethylheptane Substance Q: 5,6-dimethyl-1-heptyne The Index of Hydrogen deficiency of Q is 2 (compared with C9H20). The IR data suggests that Q is a terminal alkyne; thus, there must be no rings in its structure. The catalytic hydrogenation data provides further details of the carbon skeleton. Due to the specific substitution pattern in this carbon skeleton, there is only one possible position for a terminal triple bond. Thus, the structure given above is consistent with all of the given information. IUPAC Name: 5,6-dimethyl-1-heptyne 240 Chapter 8 MULTIPLE CHOICE QUESTIONS Topic: Structure Elucidation 1. An alkene adds hydrogen in the presence of a catalyst to give 3,4-dimethylhexane. Ozonolysis of the alkene followed by treatment with zinc and acetic acid gives a single organic product. The structure of the alkene is: CH3 A) CH3CH=C-CHCH2CH3 (cis or trans) CH3 CH3 B) CH3CH2C=CCH3 (cis or trans) CH2CH3 C) CH3 CH2=CCH2CHCH2CH3 CH3 CH2 D) CH3CH2CCHCH2CH3 CH3 CH3 E) CH3CH2CHCHCH=CH2 CH3 Ans: B 241 Chapter 8 Topic: Structure Elucidation 2. Ozonolysis of compound Z yields the products shown below. What is the structure of Z? O Z 1) O3 2) Zn, HOAc O 2HCH + CH3CCH2CH O I II III O H IV A) B) C) D) E) O V I II III IV V Ans: B 242 Chapter 8 Topic: Structure Elucidation 3. Compound C has the molecular formula C7H12. On catalytic hydrogenation, 1 mol of C absorbs 1 mol of hydrogen and yields a compound with the molecular formula C7H14. On ozonolysis and subsequent treatment with zinc and acetic acid, C yields only: O O The structure of C is: I II IV A) B) C) D) E) III V I II III IV V Ans: E Topic: Structure Elucidation 4. Compound X has the molecular formula C6H10. X decolorizes bromine in carbon tetrachloride. X also shows IR absorption at about 3300 cm-1. When treated with excess hydrogen and a nickel catalyst, X yields 2-methylpentane. The most likely structure for X is: A) B) C) D) E) Ans: D 243 Chapter 8 Topic: Structure Elucidation 5. An unknown compound, A, has the molecular formula C7H12. On oxidation with hot aqueous potassium permanganate, A yields CH3CH2COOH and (CH3)2CHCOOH. Which of the following structures best represents A? A) B) C) D) E) Ans: C 244 Chapter 8 Topic: Structure Elucidation 6. Determine a possible structure for an alkene, X, formula C9H14, on the basis of the following information: X adds one mole of hydrogen on catalytic hydrogenation. On treatment with hot basic KMnO4 followed by acidification, X yields the following dicarboxylic acid. O HO OH O A possible structure for X might be: I II IV A) B) C) D) E) III V I II III IV V Ans: C Topic: Structure Elucidation 7. An optically active compound, Y, with the molecular formula C7H12 gives a positive test with cold dilute KMnO4 and shows IR absorption at about 3300 cm-1. On catalytic hydrogenation, Y yields Z(C7H16) and Z is also optically active. Which is a possible structure for Y? A) CH3CH2CH2CH2CH2C≡CH B) (CH3)2CHCH2CH2C≡CH C) CH3CH2CH(CH3)CH2C≡CH D) CH3CH2CH(CH3)C≡CCH3 E) CH2=CHCH(CH3)CH2CH=CH2 Ans: C 245 Chapter 8 Topic: Structure Elucidation 8. One mole of an optically active compound, X, with the molecular formula C6H8 reacts with three moles of hydrogen in the presence of a catalyst to yield an optically inactive product that cannot be resolved. X also exhibits IR absorption at approximately 3300 cm-1. Which is a possible structure for X? A) (E)-4-hexen-1-yne B) (Z)-4-hexen-1-yne C) (E)-2-hexen-4-yne D) 2-methyl-1-penten-3-yne E) 3-methyl-1-penten-4-yne Ans: E Topic: Structure Elucidation 9. An alkene with the molecular formula C10H18 is treated with ozone and then with zinc and acetic acid. The product isolated from these reactions is: O O What is the structure of the alkene? I II III IV A) B) C) D) E) V I II III IV V Ans: C 246 Chapter 8 Topic: Structure Elucidation 10. An optically active compound, A, with the molecular formula C7H12 reacts with cold dilute KMnO4 and gives IR absorption at about 3300 cm-1. On catalytic hydrogenation, A is converted to B (C7H16) and B is also optically active. Which is a possible structure for A? I II III IV A) B) C) D) E) V I II III IV V Ans: E Topic: Structure Elucidation 11. Which substance would undergo the following reaction? ? A) B) C) D) E) i. O3 ii. Zn, HOAc H O + 4-Hexen-1-yne 3-methyl-1-hexene (E)-2-hexene (Z)-2-hexene 4-methyl-1-hexene Ans: E r 247 H O Chapter 8 Topic: Structure Elucidation 12. Which alkene would yield only CH3CH2COOH on oxidation with hot alkaline potassium permanganate (followed by acid work-up)? A) (E)-2-hexene B) (Z)-2-hexene C) 2-methyl-2-pentene D) (E)-3-hexene E) (E)-4-methyl-2-pentene Ans: D Topic: Structure Elucidation 13. An unknown compound, B, has the molecular formula C7H12. On catalytic hydrogenation 1 mol of B absorbs 2 mol of hydrogen and yields 2-methylhexane. B has significant IR absorption band at about 3300 and 2200 cm-1. Which compound best represents B? A) 3-methyl-1-hexyne B) 5-methyl-2-hexyne C) 5-methyl-1,3-hexadiene D) 5-methyl-1-hexyne E) 2-methyl-1,5-hexadiene Ans: D Topic: Structure Elucidation 14. What compound would yield an equimolar mixture of CH3CH2CH2CHO and CH3CHO upon treatment with O3, followed by Zn/HOAc? A) 1-Hexene B) cis-2-Hexene C) trans-2-Hexene D) More than one of these E) None of these Ans: D Topic: Structure Elucidation 15. An alkene with the molecular formula C8H16 undergoes ozonolysis to yield a mixture of (CH3)2C=O and (CH3)3CCHO. The alkene is: A) 2,2-Dimethyl-2-hexene B) 2,3-Dimethyl-2-hexene C) 2,4-Dimethyl-2-hexene D) 2,4,4-Trimethyl-2-pentene E) More than one of the above is a possible answer. Ans: D 248 Chapter 8 Topic: Structure Elucidation 16. Which of the following would decolorize bromine in carbon tetrachloride and yield a ketone upon reaction with sulfuric acid in the presence of catalytic amounts of HgSO4? A) CH3CH=CHCH3 B) CH3CH=CH2 C) CH3CH2C≡CH D) CH3CH2CH2CH3 E) All of these would give positive results in each test. Ans: C Topic: Structure Elucidation 17. Which of these compounds will react with cold concd. H2SO4, as well as Br2 in CCl4 ? A) B) C) D) E) CH3CH2CH=CHCH3 CH3CH2CH2CH=CH2 CH3CH2C≡CCH3 (CH3)2CHC≡CH All of these Ans: E Topic: Structure Elucidation 18. Which of the following reagents might serve as the basis for a simple chemical test that would distinguish between pure 1-pentene and pure pentane? A) Bromine in carbon tetrachloride B) Dilute aqueous potassium permanganate C) Concentrated sulfuric acid D) All of the above E) Answers A) and B) only Ans: D Topic: Structure Elucidation 19. A) B) C) D) E) Which reagent or test could be used to distinguish between 3-pentyne and 1-pentyne? Br2/CCl4 IR examination Concd. H2SO4 KMnO4,OHNone of these Ans: B 249 Chapter 8 Topic: Structure Elucidation 20. Which reagent or test could be used to distinguish between 2-methyl-2-pentene and 2methylpentane? A) Br2/CCl4 B) KMnO4, OH− C) Concd. H2SO4 D) Two of the above E) All of the above Ans: E Topic: Structure Elucidation 21. A) B) C) D) E) Which of the following could be used to distinguish between 1-octyne and 3-octyne? Treatment with 2 mol of HX Addition of water Reaction with KMnO4 Decolorization of bromine in CCl4 IR examination Ans: E Topic: Structure Elucidation 22. A reagent or test that could be used to distinguish between 1-pentene and 1-pentyne would be: A) Bromine in carbon tetrachloride B) Dilute aqueous potassium permanganate C) CrO3 in H2SO4 D) H2SO4 E) IR examination Ans: E Topic: Structure Elucidation 23. Which of the following could be used as the basis for a simple test that would distinguish between 1-pentyne and pentane? A) IR examination B) Br2/CCl4 C) KMnO4/H2O D) Two of these E) All of these Ans: E 250 Chapter 8 Topic: Reaction Products 24. Treating 1-methylcyclohexene with H3O+ would yield primarily which of these? HO HO HO I II III HO OH IV A) B) C) D) E) V I and V II III and V IV I, III and V Ans: D Topic: Reaction Products 25. What would be the major product of the following reaction? HCl Cl Cl Cl Cl I II III Cl Cl IV A) B) C) D) E) V I II III IV V Ans: B 251 Chapter 8 Topic: Reaction Products 26. Treating 1-methylcyclohexene with HCl would yield primarily which of these? H3C H3C Cl Cl I H3C Cl II H3C Cl III Cl IV A) B) C) D) E) V I II III IV V Ans: C Topic: Reaction Products 27. Which product would you expect from the following reaction? H3O+ H2O OH OH II I OH III OH IV A) B) C) D) E) V I II III IV V Ans: D 252 Chapter 8 Topic: Reaction Products 28. The reaction of Br2/CCl4 to cyclohexene would produce the compound(s) represented by structure(s): H H H Br H Br A) B) C) D) E) Br Br I I alone II alone II and III III alone I , II and II Ans: C Br H Br H II III Topic: Reaction Products 29. What product would you expect from addition of deuterium chloride to 2-cyclohexyl-4methyl-2-pentene? D Cl D Cl D H Cl I III II Cl D D Cl IV A) B) C) D) E) V I II III IV V Ans: B 253 Chapter 8 Topic: Reaction Products 30. A) B) C) D) E) What is the chief product of the reaction of IBr with 2-methyl-2-pentene? 2-bromo-3-iodo-2-methylpentane 3-bromo-2-iodo-2-methylpentane 1-bromo-2-iodo-2-methylpentane 2-bromo-1-iodo-2-methylpentane All of the above Ans: A Topic: Reaction Products 31. A) B) C) D) E) What is the chief product of the acid-catalyzed hydration of 2,5-dimethyl-2-hexene? 2,5-dimethyl-1-hexanol 2,5-dimethyl-2-hexanol 2,5-dimethyl-3-hexanol 2,5-dimethyl-2,3-hexanediol 2,5-dimethyl-3,4-hexanediol Ans: B Topic: Reaction Products 32. What product would result from the following reaction? KMnO4, H2O cold, dilute ? CO2H O K I A) B) C) D) E) OH OH MnO4 II III OH OH OH OH IV V I II III IV V Ans: C 254 Chapter 8 Topic: Reaction Products 33. A) B) C) D) E) Acid-catalyzed hydration of 2-methyl-1-butene would yield which of the following? (CH3)2C(OH)CH2CH3 CH2OHCH(CH3)CH2CH3 (CH3)2CHCHOHCH3 (CH3)2CHCH2CH2OH CH3CH2CH(CH3)CH2OH Ans: A Topic: Reaction Products 34. Which of these is not formed when cyclopentene reacts with an aqueous solution of bromine? Br OH OH Br I A) B) C) D) E) Br Br Br II Br III OH OH IV V I II III IV V Ans: E Topic: Reaction Products 35. What would be the major product of the following reaction? Br2, H2O ? Br OH I A) B) C) D) E) Br OH Br II OH Br Br Br III IV I II III IV V Ans: A 255 OH V Chapter 8 Topic: Reaction Products 36. Addition of hydrogen chloride to the following molecule would produce: HCl ? Cl Cl Cl Cl Cl Cl A) B) C) D) E) Cl Cl Cl Cl Cl I II III IV V I and II II and III I and IV V All of the above are equally likely to be formed Ans: A 256 Chapter 8 Topic: Reaction Products 37. In addition to the expected major product, which compound may be reasonably anticipated as a by-product in the hydroxylation of R-2-methylcyclohexene with cold alkaline permanganate? H3C i. KMnO4, H2O H cold, dilute ii. H3O H3C H H3C OH ? + H OH H3C O H OH I O II H III CH3 O CH3 H O IV A) B) C) D) E) H O OH O OH I II III IV V Ans: E 257 V Chapter 8 Topic: Reaction Products 38. Select the structure of the major product formed in the following reaction. 2 HCl ? Cl Cl Cl Cl I III II Cl Cl Cl Cl IV A) B) C) D) E) V I II III IV V Ans: D Topic: Reaction Products 39. Which of these compounds is not formed when gaseous ethene is bubbled into an aqueous solution of bromine, sodium chloride and sodium nitrate? A) BrCH2CH2Br B) BrCH2CH2Cl C) BrCH2CH2OH D) ClCH2CH2OH E) BrCH2CH2ONO2 Ans: D 258 Chapter 8 Topic: Reaction Products 40. Select the structure of the major product formed in the following reaction. 2 Cl2 ? Cl Cl Cl Cl Cl Cl Cl I II Cl III Cl Cl Cl IV A) B) C) D) E) V I II III IV V Ans: C 259 Chapter 8 Topic: Reaction Products 41. Addition of excess HBr to 2-methyl-3-heptyne would produce: 2-methyl-3,3-dichloroheptane 2-methyl-2,3-dichloroheptane I II 2-methyl-4,4-dichloroheptane 2-methyl-3,4-dichloroheptane III IV 2-methyl-3-chloroheptene V A) B) C) D) E) I and II I and III II and IV V All of the above Ans: B Topic: Reaction Products 42. What would be the major product of the following reaction? Br2, CCl4 ? CH3 CH3 H Br Br H H Br Br H C3H7 I A) B) C) D) E) CH3 CH3 H Br Br H Br H H Br C3H7 C3H7 C3H7 II III IV Equal amounts of I and II Equal amounts of II and III Equal amounts of III and IV I and II as major products, III and IV as minor products All of the above in equal amounts Ans: A 260 Chapter 8 Topic: Reaction Products 43. What would be the major product of the following reaction? Br2, CCl4 C2H5 C2H5 Br Br CH3 H3C Br H Br Br H Br H I A) B) C) D) E) C2H5 C2H5 H3C C3H7 ? Br CH3 H Br C3H7 C3H7 C3H7 II III IV Equal amounts of I and II Equal amounts of II and III Equal amounts of III and IV I and II as major products, III and IV as minor products All of the above in equal amounts Ans: A Topic: Reaction Products 44. Hydroxylation of cis-2-pentene with cold alkaline KMnO4 yields CH3 CH3 H OH HO H H H OH HO H HO C2H5 A) B) C) D) E) CH3 C2H5 CH3 OH H C2H5 HO H H OH C2H5 I II III IV Equal amounts of I and II Equal amounts of II and III Equal amounts of III and IV I and II as major products, III and IV as minor products All of the above in equal amounts Ans: B 261 Chapter 8 Topic: Reaction Products 45. The reaction of BrCl (bromine monochloride) with 1-methylcyclopentene will produce as the predominant product: CH3 CH3 Br Cl + enantiomer I A) B) C) D) E) Br Cl Br Cl + enantiomer CH3 CH2Cl Cl Br Br + enantiomer II CH3 III + enantiomer IV + enantiomer V I II III IV V Ans: D Topic: Reaction Products 46. Reaction of trans-2-hexene with a solution of Br2 in CCl4 produces: H Br H Br H Br Br H Br H I H Br II III Br H Br H IV A) B) C) D) E) H Br H Br V I and II II and V III and IV IV and V V Ans: C 262 Chapter 8 Topic: Reaction Products 47. When either cis- or trans-2-butene is treated with hydrogen chloride in ethanol, the product mixture that results includes: A) CH3CH2CH2CH2Cl B) CH3CH2CH2CH2OCH2CH3 C) CH3CH2CH(CH3)OCH2CH3 D) (CH3)3CCl E) (CH3)2CHCH2OCH2CH3 Ans: C Topic: Reaction Products 48. What is the major product of the following reaction? H2SO4, H2O ? HgSO4 OH OH OH OH I II III O O IV A) B) C) D) E) V I II III IV V Ans: D Topic: Reaction Products 49. A) B) C) D) E) Addition of 2 mol of HCl to 1-butyne would yield: CH3CH2CH2CHCl2 CH3CH2CCl2CH3 CH3CH2CHClCH2Cl CH3CH2CH=CHCl CH3CHClCHClCH3 Ans: B 263 Chapter 8 Topic: Reaction Products 50. Consider the addition of HCl to 3-methyl-1-butene. The major product of the reaction would be: A) 1-Chloro-2-methylbutane B) 1-Chloro-3-methylbutane C) 2-Chloro-2-methylbutane D) 2-Chloro-3-methylbutane E) 1-Chloropentane Ans: C Topic: Reaction Products 51. What is the final product of the following synthesis? 2-Butyne HO H H2 Ni2B (P-2) CH3 OH H CH3 I A) B) C) D) E) HO HO C4H8 CH3 H H CH3 i. OsO4 ii. NaHSO4 HO H II CH3 H OH CH3 III Final Product H HO CH3 OH H CH3 IV I II III IV An equimolar mixture of III and IV Ans: B Topic: Synthetic Strategy 52. A synthetic strategy for converting trans-2-butene into pure cis-2-butene would consist of which of the following? A) Reaction with H2, Ni2B (P-2) B) Reaction with i) Br2, CCl4; ii) 2 NaNH2, NH3(l); iii) Na, NH3 (l) C) Reaction with H3O+, heat D) Reaction with i) Br2, CCl4; ii) 2 NaNH2, NH3(l); iii) H2, Ni2B (P-2) E) None of these will successfully effect the desired transformation Ans: D 264 Chapter 8 Topic: Synthetic Strategy 53. Which reagent(s) given below could be used to synthesize cis-1,2-cycloheptanediol from cycloheptene? A) KMnO4, OH−, 5oC B) KMnO4, H3O+, 75oC C) H2SO4, heat D) All of these E) None of these Ans: A Topic: Synthetic Strategy 54. A) B) C) D) E) Which reaction sequence would convert cis-2-butene to trans-2-butene? Br2/CCl4; then 2 NaNH2; then H2/Ni2B(P-2) Br2/CCl4; then 2 NaNH2; then Li/liq. NH3 H3O+, heat; then cold dilute KMnO4 HBr; then NaNH2; then H2, Pt None of these Ans: B Topic: Synthetic Strategy 55. The conversion of ethylene to vinyl bromide can be accomplished by use of these reagents in the order indicated. A) (1) HBr; (2) NaOC2H5 B) (1) Br2; (2) NaOC2H5 C) (1) Br2; (2) H2O D) (1) NaNH2; (2) HBr E) (1) HBr; (2) H2SO4 Ans: B Topic: Synthetic Strategy 56. Cyclohexene is treated with cold dilute alkaline KMnO4. Assuming syn addition, the spatial arrangement of the two hydroxyl groups in the product would be: A) equatorial-axial B) axial-axial C) equatorial-equatorial D) coplanar E) trans Ans: A 265 Chapter 8 Topic: Synthetic Strategy 57. A) B) C) D) E) Which of the following reactions of cyclobutene would yield a meso product? Reaction with H3O+, H2O Reaction with Br2, CCl4 Reaction with Cl2, CCl4 Reaction with D2, Pt Reaction with hot, alkaline KMnO4, followed by acid workup Ans: E Topic: Reaction Products 58. How many compounds are possible from the addition of bromine to CH2=CHCH2CH3 (counting stereoisomers separately)? A) One B) Two C) Three D) Four E) Five Ans: B Topic: Reaction Products 59. Which alkene would react with cold dilute alkaline permanganate solution to form an optically inactive and irresolvable product? A) B) C) D) E) Ans: C 266 Chapter 8 Topic: Reaction Products 60. A) B) C) D) E) Which reaction of an alkene proceeds with anti addition? Hydroboration/oxidation Bromination Oxidation with cold KMnO4 Hydrogenation Oxymercuration-demercuration Ans: B Topic: Reaction Products 61. A) B) C) D) E) A pair of enantiomers results from which of these reactions? cyclopentene + cold, dil. KMnO4 ⎯⎯⎯⎯→ trans-2-butene + Br2 ⎯⎯⎯⎯→ 1-pentene + HCl ⎯⎯⎯⎯→ cis-2-butene + D2/Pt ⎯⎯⎯⎯→ cyclobutene + OsO4, then Na2SO3 ⎯⎯⎯⎯→ Ans: C Topic: Reaction Products 62. A) B) C) D) E) Which reaction would yield a racemic product? cyclopentene + D2/Pt ⎯⎯⎯⎯→ Cyclopentene + OsO4, then Na2SO3 ⎯⎯⎯⎯→ cyclopentene + Br2/H2O ⎯⎯⎯⎯→ Cyclopentene + cold, dilute KMnO4 ⎯⎯⎯⎯→ Cyclopentene + dilute H2SO4 ⎯⎯⎯⎯→ Ans: C Topic: Reaction Products 63. 3,3-dimethylcyclohexene is subjected to reaction with cold, dilute KMnO4, to give 3,3dimethyl-1,2-cyclohexanediol. In the most stable conformation of the product, the hydroxyl groups would be: A) both axial B) both equatorial C) axial-equatorial D) coplanar E) None of these Ans: B 267 Chapter 8 Topic: Reaction Products 64. Cyclohexene reacts with bromine to yield 1,2-dibromocyclohexane. Molecules of the product would: A) be a racemic form and, in their most stable conformation, they would have both bromine atoms equatorial. B) be a racemic form and, in their most stable conformation, they would have one bromine atom equatorial and one axial. C) be a meso compound and, in its most stable conformation, it would have both bromine atoms equatorial. D) be a meso compound and, in its most stable conformation, it would have one bromine atom equatorial and one axial. E) be a pair of diastereomers and, in their most stable conformation, one would have the bromines equatorial and axial, and the other would have the bromines equatorial and equatorial. Ans: A Topic: Reaction Products 65. Which reaction would yield a meso compound? Br2/CCl4 A) cis-2-Butene H2/Pd B) cis-2-Butene i) OsO4 C) cis-2-Butene ii) NaHSO3 dil KMnO4 D) trans-2-Butene 5oC E) None of these Ans: C Topic: Reaction Products 66. A) B) C) D) E) Which reaction would give a meso compound as the product? Cyclopentene + Br2/CCl4 Cyclopentene + OsO4, then NaHSO3 Cyclopentene + RCO3H, then H3O+ Cyclopentene + Cl2, H2O More than one of these Ans: B 268 Chapter 8 Topic: Reaction Products 67. A) B) C) D) E) Which of the following reactions would yield the final product as a racemic form? Cyclohexene + a peroxy acid, then H3O+ Cyclohexene + cold, dilute KMnO4 and OHCyclohexene + HCl Cyclohexene + OsO4, then NaHSO3 Cyclohexene + D2/Pt Ans: A Topic: Reaction Products 68. (R)-3-Chloro-1-butene reacts with HCl by Markovnikov addition, and the products are separated by gas chromatography. How many total fractions would be obtained and how many would be optically active? A) One optically active fraction only B) One optically active fraction and one optically inactive C) Two optically active fractions D) One optically active fraction and two optically inactive E) Two optically active fractions and one optically inactive Ans: B Topic: Reaction Products 69. The interaction of the π bond of an alkene with an electrophile can initially result in the formation of a species termed a π complex. Which of these cannot combine with an alkene to form a π complex? A) H+ B) NH3 C) Ag+ D) Hg2+ E) BF3 Ans: B Topic: Reaction Products 70. A) B) C) D) E) Markovnikov addition of HI to 2-methyl-2-butene involves: initial attack by an iodide ion. initial attack by an iodine atom. isomerization of 2-iodo-2-methylbutene. formation of a carbocation at C-2. formation of carbocation at C-3. Ans: D 269 Chapter 8 Topic: Reaction Products 71. Which reaction is NOT stereospecific? trans-2-Butene Br2/CCl4 cis-2-Pentene I Br2/H2O II 1-Methylcyclohexene H2/Pd III 2-Methyl-2-heptene dil KMnO4 trans-2-Hexene 5oC V IV A) B) C) D) E) I II III IV V Ans: E 270 HBr Chapter 8 Topic: Reaction Products 72. Which reaction is regioselective? Cl I II ICl I Br Br2 Br OH III KMnO4 OH IV A) B) C) D) E) D2/Ni H D D H I II III IV None of these Ans: A Topic: General Information 73. The thermodynamic parameters at 298 K for the following reaction are given below. gas phase CH2=CH2 + HCl CH3CH2Cl ΔHº = -64.9 kJ mol-1 ΔSº = -131 J K-1 mol-1 ΔGº = -25.8 kJ mol-1 Which of the following statements is true of the reaction? A) Both ΔHº and ΔSº favor product formation. B) Neither ΔHº nor ΔSº favors product formation. C) The entropy term is unfavorable but the formation of ethyl chloride is favored. D) The entropy term is favorable but the formation of ethyl chloride is not favored. E) The sign of ΔGº indicates that the reaction cannot occur as written. Ans: C 271 Chapter 8 Topic: Reaction Products 74. In general, when the addition of an unsymmetrical electrophilic reagent to an unsymmetrical alkene forms the product predicted by Markovnikov's rule, that occurs because: A) the product is statistically favored. B) steric hindrance favors its formation. C) it is formed via the more/most stable carbocation. D) it is the more/most stable product. E) All of the above are reasons. Ans: C Topic: General Information 75. Which of these compounds belongs to the class of substances commonly known as "halohydrins"? A) BrCH2CH2Cl B) ClCH2CO2H C) ICH2CH2OH D) FCH2CH2NH2 E) HOCH2COCl Ans: C Topic: General Information 76. A) B) C) D) E) Which alkene would you expect to be most reactive toward acid-catalyzed hydration? 1 pentene trans-2-pentene cis-2-pentene 2-methyl-1butene All of these would be equally reactive. Ans: D Topic: General Information 77. A) B) C) D) E) The most resistant compound to the action of hot alkaline KMnO4 is: Pentane 1-Pentene 2-Pentene 2-Pentyne Cyclopentene Ans: A 272 Chapter 8 Topic: General Information 78. A) B) C) D) E) 2-Pentyne will not react with: H2, Pt Br2 NH3 H2SO4 KMnO4/H2O Ans: C Topic: General Information 79. Consider the ozonolysis products obtained from all the unbranched and unsymmetrical isomers of heptene. The reaction product in each case would consist of: A) a single aldehyde. B) an aldehyde and a ketone. C) two different ketones. D) two different aldehydes. E) a single ketone. Ans: D SHORT ANSWER QUESTIONS Topic: General Information 80. The rule that correctly predicts the regiochemistry of most ionic additions to alkenes is called ____________________. Ans: Markovnikov's Rule Topic: General Information 81. When a reaction that could potentially yield two or more constitutional isomers instead produces only one as the major product, the reaction is said to be _____________________. Ans: regioselective Topic: General Information 82. When a particular stereoisomer reacts in such a way that it gives a particular stereoisomer as a product, even if more than one stereoisomer is theoretically possible, the reaction is said to be _____________. Ans: stereospecific 273 Chapter 8 Topic: General Information 83. A reaction in which the reactant is not necessarily chiral but still produces primarily one stereoisomeric form of the product (or a specific subset of the possible stereoisomers) is referred to as a _________________ reaction. Ans: stereoselective Topic: General Information 84. Hydroboration-oxidation is a reaction with _________ stereochemistry and ________________ regiochemistry. Ans: syn, anti-Markovnikov Topic: General Information 85. Even when one or more stereogenic centers are produced as the result of an addition reaction to an alkene, the product is always formed as a racemic mixture. Why is that? Ans: Because alkenes are planar, and the reagent can add from either face. Topic: General Information 86. The “decolorization” of molecular bromine is often used as a functional group test to detect the presence of ________________. Ans: carbon-carbon multiple bonds; or, alkenes and alkynes Topic: General Information 87. Neutral divalent carbon compounds are called ___________. Ans: carbenes Topic: General Information 88. Carbenes are frequently produced by α-elimination reactions. These are reactions in which the proton being lost and the leaving group are ___________. Ans: both attached to the same carbon Topic: General Information 89. π bonds are quite susceptible to reaction with electron-seeking reagents, also referred to as ____________________. Ans: electrophiles 274 Chapter 8 Topic: Reaction Sequence 90. Predict the final product(s) obtained when (2R,3R)-2-bromo-3-methylpentane is subjected to the following sequence of reactions, briefly explaining your rationale. Provide regiochemical and stereochemical details as relevant. NaOC2H5/C2H5OH, heat i) ii) BH3, THF H2O2, OH− iii) H Ans: Br H E-3-methyl-2-hexene NaOC2H5 C2H5OH CH3 H3C H Hydroboration/oxidation: (E2: anti overall (2R,3R) elimination) Anti-Markovnikov, syn addition of H2O H OH HO H + H3C H H CH3 (2S,3R) (2R,3S) 3-methyl-2-pentanol Heating with sodium ethoxide results in E2 elimination; the anti- elimination leads to the formation of E-3-methyl-2-hexene as the major product. Subsequent hydroboration oxidation is regioselective (anti-Markovnikov) and stereospecific (syn), resulting in the formation of racemic (2S,3R & 2R,3S) 3-methyl-2-pentanol. The other diastereomer pair (2S,3S & 2R,3R) is not expected to be obtained. Topic: Reaction Products 91. Provide a mechanistic explanation for the following observation: The same major product is obtained when 2-ethyl-1-hexene and 3-methyl-2-heptene are allowed to react with HCl. Ans: HCl Cl HCl most stable carbocation Both alkenes are unsymmetrically substituted: the major product is a consequence of regioselective addition to the double bond. Upon reaction with HCl, electrophilic addition of a proton results in the formation of the most stable intermediate carbocation, which then reacts with Cl−, to give the observed product. 275 Chapter 8 Topic: Reaction Products 92. Predict the major product(s) of the following reaction, giving regiochemical and/or stereochemical details as relevant. Br2, H2O ? Ans: OH Br H OH Br H + The reaction takes place with Markovnikov regioselectivity and anti stereospecificity, giving a racemic mixture of the halohydrin as the major product. Topic: Reaction Products 93. Draw Fischer projection formula(s) of the major product(s) of the reaction between Z-2-methyl3-hexene and cold, alkaline KMnO4. Ans: CH(CH ) CH(CH ) 3 2 cold, dil KMnO4 3 2 H OH HO H H OH + HO H C2H5 C2H5 The reaction takes place with syn stereospecificity, giving a racemic mixture of the diol product. Topic: Reaction Products 94. Draw Fischer projection formula(s) of the major product(s) of the reaction between Z-3-methyl3-hexene and cold, alkaline KMnO4. CH2CH3 CH2CH3 Ans: OH HO CH3 cold, dil H3C + H H OH HO KMnO4 C2H5 C2H5 The reaction takes place with syn stereospecificity, giving a racemic mixture of the diol product. 276 Chapter 8 Topic: Reaction Products 95. Draw Fischer projection formulas of the major product of the reaction between E-2-methyl-3hexene and aqueous Br2. Ans: CH(CH ) CH(CH ) CH(CH ) CH(CH ) 3 2 Br2 H2O HO H H Br 3 2 H + Br C2H5 3 2 OH H H Br + HO H C2H5 + 3 2 Br H H OH C2H5 C2H5 The reaction takes place with anti stereospecificity. Since the alkene is symmetrically substituted, Markovnikov rule is not applicable, and the reaction is not regioselective. The product mixture would therefore consist of 2 pairs of enantiomers, that are constitutional isomers of each other. Topic: Reaction Products 96. Give a mechanistic explanation for the formation of the following product in significant yield. What other product(s) might also be obtained? Explain clearly. HI Ans: H+ + I fast I− + I + I − I The regioselective addition of a proton first generates a secondary carbocation, which can undergo rearrangement to a more stable 3o carbocation by two alternate pathways. One pathway results in ring expansion to a more stable 5-membered ring. This pathway is thus more likely, which would then lead to the observed product. The other pathway is less likely, since ring strain is not relieved; however, this could lead to a minor product, as shown above. 277 Chapter 8 Topic: Structure Elucidation 97. Deduce the structure of an unknown compound A, C8H16, from the following data. Briefly, but clearly explain your rationale. A decolorizes Br2/CCl4, and upon reaction with excess H2/Ni, affords 1-ethyl-2-methylcyclopentane. When A is subjected to ozonolysis, the following product is obtained. O O Ans: A must be 3-ethyl-4-methylcyclopentene. This given data can be explained as shown below: C8H14: Index of Hydrogen Deficiency of A = 2 decolorizes Br2,CCl4: A must contain pi bonds A H2, Ni A must contain some the same carbon skeleton and one pi bond ozonolysis O O O O pi bond position in A deduced from the structure of the ozonolysis product Topic: Reaction Products 98. Predict the product(s) of the oxidation of 2,3,4-trimethyl-1,5-heptadiene with hot, alkaline KMnO4. Ans: OH hot, alkaline CO + H O + O + 2 2 O KMnO4 O OH 278 Chapter 8 Topic: Reaction Products 99. Predict the structure of product obtained when cis-2-hexene is allowed to react with Zn/CH2I2. H Ans: H Zn, CH2I2 + H H The Zn/CH2I2 produces a carbene which reacts with the alkene to give the corresponding cyclopropane derivative. The reaction proceeds with retention of alkene stereochemistry, resulting in a racemic mixture of the two cis enantiomers. Topic: Reaction Products 100. Predict the structure of product obtained when 1-hexyne is allowed to react with aqueous H2SO4 in the presence of catalytic amounts of HgSO4. Ans: HgSO4, H2SO4, H2O OH O The reaction of 1-hexyne with aqueous H2SO4, in the presence of catalytic amounts of HgSO4, results in regioselective hydration to produce an enol, which tautomerizes to the more stable keto form. 279 Chapter 9 MULTIPLE CHOICE QUESTIONS Topic: Proton NMR- Chemical Shift, Splitting, Etc. 1. If all the protons of 1-fluoropentane could be discerned, which would you expect to be at the lowest field in the 1H NMR spectrum of this compound? CH3CH2CH2CH2CH2F A) B) C) D) E) V IV III II I Protons on carbon I Protons on carbon II Protons on carbon III Protons on carbon IV Protons on carbon V Ans: A Topic: Proton NMR- Chemical Shift, Splitting, Etc. 2. Which proton(s) of the compound below would appear as a septet in the 1H NMR spectrum? I CH3 CH3CH2CH2-O-CH CH3 V IV III II I A) The protons on carbon I B) The proton on carbon II C) The protons on carbon III D) The protons on carbon IV E) The protons on carbon V Ans: B Page 280 Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 3. Which proton(s) of the compound below would appear as a doublet in the 1H NMR spectrum? I CH3 CH3CH2CH2-O-CH CH3 V IV III II I A) The protons on carbon I B) The protons on carbon II C) The protons on carbon III D) The protons on carbon IV E) The protons on carbon V Ans: A Topic: Proton NMR- Chemical Shift, Splitting, Etc. 4. Which proton(s) of the compound below would appear as a triplet in the 1H NMR spectrum? I CH3 CH3CH2CH2-O-CH CH3 II V IV III I A) The protons on carbon II B) The protons on carbon I and V C) The protons on carbon III and V D) The protons on carbon III and IV E) The protons on carbon V Ans: C Topic: Proton NMR- Chemical Shift, Splitting, Etc. 5. How many signals would you expect to find in the 1H NMR spectrum of CH3OCH2CH2OCH3? A) 1 B) 2 C) 3 D) 4 E) 5 Ans: B 281 Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 6. Predict the splitting pattern you would observe for the proton at C3 of 2,3-dimethyl-2phenylbutane. A) B) C) D) E) Doublet Singlet Quartet Septet Octet Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc. 7. Predict the splitting pattern you would observe for the proton at C1 of 2,3-dimethyl-2phenylbutane. A) B) C) D) E) Doublet Singlet Quartet Septet Octet Ans: B Topic: Proton NMR- Chemical Shift, Splitting, Etc. 8. Predict the splitting pattern you would observe for the proton at C4 of 2,3-dimethyl-2phenylbutane. A) B) C) D) E) Doublet Singlet Quartet Septet Octet Ans: A 282 Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 9. What feature would you expect to see in the 1H NMR spectrum of B after subjecting A to the following reaction? Cl2 C8H9Cl + HCl heat or light (chief product) A B A) B) C) D) E) There would be only 4 aromatic protons at low field. The signal for the protons on the benzylic carbon would be a doublet. The signal for the methyl protons would be a triplet. The signal for the methyl protons would be a doublet. The signal for the methyl protons would integrate for only 2 hydrogens. Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc. 10. A) B) C) D) E) How many 1H NMR signals would trans-1,2-dichlorocyclopropane give? 1 2 3 4 5 Ans: B Topic: Proton NMR- Chemical Shift, Splitting, Etc. 11. How many 1H NMR signals would the following compound give? ClCH2CHCH3 A) B) C) D) E) Br 1 2 3 4 5 Ans: D 283 Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 12. A) B) C) D) E) How many 1H NMR signals would cis-1,2-dichlorocyclopropane give? 1 2 3 4 5 Ans: C Topic: Proton NMR- Chemical Shift, Splitting, Etc. 13. How many 1H NMR signals would you expect from this compound? OCH3 OCH3 A) B) C) D) E) 1 2 3 4 5 Ans: B Topic: Proton NMR- Chemical Shift, Splitting, Etc. 14. The 1H NMR signal for which of the indicated protons occurs furthest downfield? III Cl H H C C C C CH3 I H IV II V A) B) C) D) E) I II III IV V Ans: E 284 Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 15. The 1H NMR spectrum of which of the compounds below, all of formula C7H12O2, would consist of two singlets only? O O O O O O I II III O O O O IV A) B) C) D) E) V I II III IV V Ans: E Topic: Proton NMR- Chemical Shift, Splitting, Etc. 16. The 1H NMR spectrum of which of the compounds below, all of formula C7H12O2, would consist of three singlets only? O O O O O I II III O O O O IV A) B) C) D) E) V I II III IV V Ans: B 285 O Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 17. The 1H NMR spectrum of which of the compounds below, all of formula C7H12O2, would consist of a singlet, a doublet and a triplet only? O O O O O O I II III O O O O IV A) B) C) D) E) V I II III IV V Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc. 18. The 1H NMR spectrum of which of these compounds would consist of a triplet, singlet and quartet only? A) 2-chloro-4-methylpentane B) 3-chloro-2-methylpentane C) 3-chloropentane D) 1-chloro-2,2-dimethylbutane E) 3-chloro-3-methylpentane Ans: E Topic: Proton NMR- Chemical Shift, Splitting, Etc. 19. In NMR terminology, protons Ha and Hb are said to be: H Cl Hb A) B) C) D) E) Ha Identical Enantiotopic Diastereotopic Homotopic Mesotopic Ans: C 286 Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 20. Consider the 1H NMR spectrum of very pure 1-propanol. Assuming the maximum multiplicity of signals and non-superposition of peaks, what is the expected signal splitting pattern for each signal, in the order (a, b, c, d) ? CH3-CH2-CH2-OH b c d a A) B) C) D) E) 3, 6, 4, 1 3, 6, 4, 3 3, 12, 3, 1 3, 12, 3, 3 3, 12, 6, 3 Ans: C Topic: Proton NMR- Chemical Shift, Splitting, Etc. 21. In the structure shown, Hb and Hc are classified as: Ha Hb Hc A) B) C) D) E) homotopic protons. vicinal protons. enantiotopic protons. diastereotopic protons. isomeric protons. Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc. 22. In the structure shown, Hb and Hc are classified as: Hb A) B) C) D) E) Ha homotopic protons. vicinal protons. enantiotopic protons. diastereotopic protons. isomeric protons. Ans: C 287 Chapter 9 Topic: Proton NMR- Chemical Shift, Splitting, Etc. 23. In the structure shown, Hb and Hc are classified as: Ha Hb A) B) C) D) E) homotopic protons. vicinal protons. enantiotopic protons. diastereotopic protons. isomeric protons. Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc. 24. In the structure shown, Hb and Hc are classified as: HO H Ha H b A) B) C) D) E) homotopic protons. vicinal protons. enantiotopic protons. diastereotopic protons. isomeric protons. Ans: D Topic: Proton NMR- Chemical Shift, Splitting, Etc. 25. Distinction between the methine protons in the compounds I and II below should be possible in the 1H NMR spectra if: H C2H5 H3C A) B) C) D) E) Cl C2H5 H3C Cl H I II a very high field instrument is used. the spectra are determined in a chiral solvent. a long scan time is used for each compound. a high amplitude setting is employed. Distinction between the enantiomers is impossible. Ans: B 288 Chapter 9 Topic: Proton NMR- Unknown Identification. 26. A compound with the molecular formula C4H10O gives a 1H NMR spectrum consisting only of a quartet centered at δ 3.5 and a triplet at δ 1.1. The most likely structure for the compound is: CH3 A) CH3COH B) C) D) E) CH3 CH3 CH3OCHOH CH3CH2CH2CH2OH CH3CH2OCH2CH3 CH3CHCH2OH CH3 Ans: D Topic: Proton NMR- Unknown Identification. 27. Determine the most likely structure of a compound, with the molecular formula C9H12, which gave a 1H NMR spectrum consisting of: a doublet at δ 1.25 a septet at δ 2.90 and a multiplet at δ 7.25 I II III IV V ] A) B) C) D) E) I II III IV V Ans: D 289 Chapter 9 Topic: Proton NMR- Unknown Identification. 28. A compound with the molecular formula C10H13Cl gave the following 1H NMR spectrum: singlet, δ 1.6 singlet, δ 3.1 multiplet, δ 7.2 (5H) The most likely structure for the compound is: Cl Cl I Cl II III Cl Cl IV A) B) C) D) E) V I II III IV V Ans: B Topic: Proton NMR- Unknown Identification. 29. A compound with the molecular formula C8H9BrO gave the following 1H NMR spectrum: triplet, δ 1.4 quartet, δ 3.9 multiplet, δ 7.0 (4H) There was no evidence of an -OH band in the IR spectrum. A possible structure for the compound is: O O Br O Br Br I II III O Br Br IV A) B) C) D) E) O V I II III IV V Ans: C 290 Chapter 9 Topic: Proton NMR- Unknown Identification 30. A compound with the molecular formula C6H15N gave the following 1H NMR spectrum: triplet, δ 0.90 quartet, δ 2.4 There were no other signals. The most likely structure for the compound is: A) CH3NCH2CH3 B) CH2CH2CH3 CH3NCH2CH2CH2CH3 CH3 C) CH3CH2CH2CH2CH2CH2NH2 D) CH3CH2NCH2CH3 CH2CH3 E) CH3CH2CH2NCH2CH2CH3 H Ans: D Topic: Proton NMR- Unknown Identification 31. A compound with the molecular formula C8H9ClO gave the following 1H NMR spectrum: triplet, δ 3.7 triplet, δ 4.2 multiplet, δ 7.1 There was no evidence of an -OH band in the IR spectrum. The most likely structure for the compound is: Cl O O O Cl Cl I II III O Cl Cl IV A) B) C) D) E) O V I II III IV V Ans: A 291 Chapter 9 Topic: Proton NMR- Unknown Identification 32. A compound with the molecular formula C3H6Cl2 gave a 1H NMR spectrum consisting only of a triplet centered at δ 3.7 and a quintet centered at δ 2.2. The most likely structure for the compound is: A) CH3CH2CHCl2 B) CH3CHClCH2Cl C) ClCH2CHClCH3 D) ClCH2CH2CH2Cl E) CH3CCl2CH3 Ans: D Topic: Proton NMR- Unknown Identification 33. A compound with the molecular formula C10H14 gave the following 1H NMR spectrum: doublet, δ 1.2 singlet, δ 2.3 septet, δ 2.8 multiplet, δ 7.1 A possible structure for the compound is: I II IV A) B) C) D) E) III V I II III IV V Ans: B 292 Chapter 9 Topic: Proton NMR- Unknown Identification 34. A compound C5H10O gave the following spectral data: 1 H NMR spectrum IR spectrum, doublet, δ 1.10 strong peak singlet, δ 2.10 near 1720 cm-1 septet, δ 2.50 Which is a reasonable structure for the compound? O O II I O IV A) B) C) D) E) O III O V I II III IV V Ans: E Topic: Proton NMR- Unknown Identification 35. A compound C4H9Br gave the following 1H NMR spectrum: multiplet, δ 4.1 (1H); multiplet, δ 1.8; doublet, δ 1.7; triplet, δ 1.0 (3H) Which is a reasonable structure for the compound? A) CH3CH2CHBrCH3 B) CH3CH2CH2CH2Br C) (CH3)2CHCH2Br D) (CH3)3CBr Ans: A 293 Chapter 9 Topic: Proton NMR- Unknown Identification 36. Determine the likely structure for a compound A (C6H10O), which is found to decolorize bromine in carbon tetrachloride. Its spectral data is as follows: 1 H NMR IR -1 triplet, δ 1.0 singlet, δ2.4 2200 cm (sharp) singlet, δ 1.4 singlet, δ3.4 3300 cm-1 (sharp) quartet, δ 1.6 3500 cm-1 (broad) OH OH I II OH IV A) B) C) D) E) OH III OH V I II III IV V Ans: C 294 Chapter 9 Topic: C-13 NMR- Symmetry, Chemical shift. 37. The broadband proton-decoupled 13C NMR spectrum of a hexyl chloride exhibits five signals. Which of these structures could be the correct one for the compound? CH3 A) CH3CCH2CH2Cl CH3 Cl B) CH3CH2CCH2CH3 CH3 CH3 CH3 C) CH3C CHCH3 Cl CH3 D) CH3CHCHCH2CH3 Cl CH3 E) CH3C CHCH3 CH3 Cl Ans: D Topic: C-13 NMR- Symmetry, Chemical shift 38. How many signals will be recorded in the broadband proton-decoupled 13C spectrum of 4-chloro-1-ethylbenzene? Cl A) B) C) D) E) 2 3 4 6 7 Ans: D 295 Chapter 9 Topic: C-13 NMR- Symmetry, Chemical shift 39. How will the methyl carbon appear in the proton off-resonance decoupled 13C spectrum of toluene? A) B) C) D) E) Singlet Doublet Triplet Quartet Quintet Ans: D Topic: C-13 NMR- Symmetry, Chemical shift 40. How many 13C signals would 1,4-dimethylbenzene give? A) B) C) D) E) 1 2 3 4 5 Ans: C Topic: C-13 NMR- Symmetry, Chemical shift 41. How many 13C signals would 1,3-dichlorobenzene give? Cl Cl A) B) C) D) E) 1 2 3 4 5 Ans: D 296 Chapter 9 Topic: C-13 NMR- Symmetry, Chemical shift 42. How many 13C signals would 1,2-dimethylbenzene give? A) B) C) D) E) 1 2 3 4 5 Ans: D Topic: C-13 NMR- Symmetry, Chemical shift 43. How many 13C signals would you expect from C6H5OCH3? O A) B) C) D) E) 1 2 3 4 5 Ans: E Topic: C-13 NMR- Symmetry, Chemical shift 44. The C7 compound which gives 3 signals in the broadband proton-decoupled 13C spectrum could be: A) Heptane B) 2-Methylhexane C) 3,3-Dimethylpentane D) 2,4-Dimethylpentane E) 2,2,3-Trimethylbutane Ans: D 297 Chapter 9 Topic: Proton NMR- Symmetry, Splitting, Chemical shift 45. Which of these compounds will not be represented by a singlet only in the 1H NMR spectrum? A) Neopentane B) Hexamethylbenzene C) Isobutane D) (Z)-1,2-Dichloroethene E) (E)-1,2-Dichloroethene Ans: C Topic: Proton NMR- Symmetry, Splitting, Chemical shift 46. For the C2 methylene group in 1-bromopropane, the theoretical multiplicity in the 1H NMR spectrum, presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, is which of these? A) B) C) D) E) CH3 CH2 CH2 c b a Br 2 5 6 8 12 Ans: E Topic: Proton NMR- Symmetry, Splitting, Chemical shift 47. A compound C5H11Cl which exhibits only two singlets in the 1H NMR spectrum must be: A) 1-Chloropentane B) 1-Chloro-2,2-dimethylpropane C) 1-Chloro-2-methylbutane D) 3-Chloropentane E) 1-Chloro-3-methylbutane Ans: B 298 Chapter 9 Topic: Proton NMR- Symmetry, Splitting, Chemical shift 48. A downfield (δ 9-10) singlet is observed in the 1H NMR spectrum of: O A) B) CH3CCH2CH3 H C6H5CH2C H C) O (CH3)2CHC H O D) E) (CH3)3CC O O C6H5CH2CCH3 Ans: D Topic: Proton NMR- Symmetry, Splitting, Chemical shift 49. Consider the expected splitting of signal “b” in the 1H NMR spectrum of N-methyl-1propanamine, shown below. Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”? d H b N a A) B) C) D) E) c e 2 5 6 8 12 Ans: E 299 Chapter 9 Topic: Proton NMR- Symmetry, Splitting, Chemical shift 50. Consider the expected splitting of signal “b” in the 1H NMR spectrum of 1-methoxy-2methylpropane, shown below. Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”? a a A) B) C) D) E) b O c d 8 9 12 21 24 Ans: D Topic: Proton NMR- Symmetry, Splitting, Chemical shift 51. Consider the expected splitting of signal “b” in the 1H NMR spectrum of 1,1-dichloro-3methylbutane, shown below. Presuming that Jab is sufficiently different from Jbc and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”? Cl a a A) B) C) D) E) b c d Cl 8 9 12 18 21 Ans: E 300 Chapter 9 Topic: Proton NMR- Symmetry, Splitting, Chemical shift 52. Consider the expected splitting of signal “b” in the 1H NMR spectrum of 1,2dimethoxypropane, shown below. Presuming that Jbc is sufficiently different from Jbd and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “b”? c a O A) B) C) D) E) b O e d 2 5 6 8 12 Ans: E Topic: Proton NMR- Symmetry, Splitting, Chemical shift 53. Consider the expected splitting of signal “c” in the 1H NMR spectrum of 2-ethyl-1butanol, shown below. Presuming that Jbc is sufficiently different from Jcd and that the instrument has sufficient resolving power, what is the theoretical multiplicity of signal “c”? a b a A) B) C) D) E) b c OH d e 6 7 8 12 15 Ans: E 301 Chapter 9 Topic: Proton NMR- Symmetry, Splitting, Chemical shift 54. Consider the expected splitting of the C2 proton signal in the 1H NMR spectrum of 2ethyl-1,3-propanediol. Presuming that the coupling constants for neighboring protons are sufficiently different, and that the instrument has sufficient resolving power, what is the theoretical multiplicity of the C2 proton signal? A) B) C) D) E) 6 7 8 12 15 Ans: E Topic: Proton NMR- Symmetry, Splitting, Chemical shift 55. What is the theoretical multiplicity of the C-2 proton signal in the 1H NMR spectrum of 2-hydroxymethyl-1,3-propanediol, shown below? OH HO A) B) C) D) E) OH 1 6 7 8 9 Ans: C Topic: Proton NMR- Symmetry, Splitting, Chemical shift 56. Consider the expected 1H NMR spectrum of 1,1,3,3-trimethylcyclopentane. Which of the following is likely to be observed? A) B) C) D) E) 7 signals: all singlets 7 signals: 4 singlets, 3 doublets 3 signals: all singlets 3 signals: one singlet, 2 doublets 3 signals: two singlets, one doublet Ans: E 302 Chapter 9 Topic: Proton NMR- Symmetry, Splitting, Chemical shift 57. Consider the expected 1H NMR spectrum of 2,4-dimethyl-1,4-pentadiene. Which of the following is likely to be observed? A) B) C) D) E) 7 signals: all singlets 4 signals: all singlets 3 signals: all singlets 3 signals: one singlet, 2 doublets 4 signals: two singlets, two doublets Ans: B Topic: Proton NMR- Symmetry, Splitting, Chemical shift 58. Consider the expected splitting of the C2 proton signal in the 1H NMR spectrum of 1,1dibromopentane. Presuming that the coupling constants for neighboring protons are sufficiently different, and that the instrument has sufficient resolving power, what is the theoretical multiplicity of the C2 proton signal? A) 3 B) 4 C) 5 D) 6 E) 8 Ans: D 303 Chapter 9 Topic: Carbon NMR- Symmetry, Chemical shift 59. A bromodichlorobenzene which gives four signals in the broadband proton-decoupled 13 C spectrum could be: Br Cl Cl Br Cl Br Cl Cl Cl I II III Cl Br Cl Br Cl IV A) B) C) D) E) Cl V I II III IV V Ans: A Topic: Carbon NMR- Symmetry, Chemical shift 60. In 13C NMR spectroscopy, the signal due to this type of carbon occurs furthest downfield. A) –C≡N B) C O C) C O C X D) E) –C≡C– Ans: B 304 Chapter 9 Topic: Mass Spectrometry. Use the following to answer Q 61-62 Topic: Mass Spectrometry. 61. A) B) C) D) E) Which is the base peak? 15 29 44 45 100 Ans: B Topic: Mass Spectrometry. 62. A) B) C) D) E) Which is the likely molecular ion (M+•)? 15 29 44 45 100 Ans: C Topic: Mass Spectrometry. 63. What is the molecular formula of this compound? A) B) C) D) E) m/z 84 M+• 85 86 C5H10O C5H8O C5H24 C6H12 C4H6O2 Ans: B intensity 10.00 0.56 0.04 305 Chapter 9 Topic: Mass Spectrometry. 64. What is the molecular formula of this compound? A) B) C) D) E) m/z 78 M+• 79 80 81 C6H6 C3H5Cl C6H8 C6H9 C3H7Cl Ans: E intensity 10.00 1 3.3 0.3 Topic: Mass Spectrometry. 65. The mass spectra of alkyl bromides and chlorides are characterized by an unusually intense __________. A) base peak B) parent peak C) M+• +1 peak D) M+• +2 peak E) None of these Ans: D Topic: Mass Spectrometry. 66. A) B) C) D) E) Predict the base peak for 2-chloro-2-methylpropane m/z 15 m/z 92 m/z 43 m/z 57 m/z 77 Ans: D 306 Chapter 9 Topic: Mass Spectrometry. 67. A) B) C) D) E) Select the structure of a compound C6H14 with a base peak at m/z 43. CH3CH2CH2CH2CH2CH3 (CH3CH2)2CHCH3 (CH3)3CCH2CH3 (CH3)2CHCH(CH3)2 None of these Ans: D Topic: Mass Spectrometry. 68. The data below from the molecular ion region of the mass spectrum of a halogencontaining compound are consistent with the presence of what halogen(s) in the original compound? intensity A) B) C) D) E) 51.0 M+• + 100.0 M • +2 + 49.0 M • +4 One Br One Cl One Br and one Cl Two Br Two Cl Ans: D Topic: Mass Spectrometry. 69. A) B) C) D) E) A prominent (M+• -18) peak suggests that the compound might be a(n): alkane alcohol ether ketone primary amine Ans: B 307 Chapter 9 Topic: Structure Elucidation 70. An organic compound absorbs strongly in the IR at 1687 cm-1. Its 1H NMR spectrum consists of two signals, a singlet at 2.1 ppm and a multiplet centered at 7.1 ppm. Its mass spectrum shows significant peaks at m/z 120, m/z 105 and m/z 77. This information is consistent with which of the following structures? O O I II IV A) B) C) D) E) O III V I II III IV V Ans: A SHORT ANSWER QUESTIONS Topic: General 71. Which form of electromagnetic radiation possesses the least energy? Ans: radiofrequency radiation Topic: General 72. “NMR” stands for _______________________. Ans: nuclear magnetic resonance Topic: General; Signal Integration 73. When measuring the integral for a particular peak in the NMR spectrum, we are not interested in the peak height as much as in the ____________________. Ans: area under the peak 308 Chapter 9 Topic: General; Chemical Shift 74. A shielded proton will absorb at a higher frequency (this is the ________ end of the spectrum); and a deshielded proton will absorb at a lower frequency (the _____________ end of the spectrum). Ans: upfield; downfield Topic: Reference Compound 75. What compound is used as the standard “zero” reference in both carbon and proton NMR? Ans: TMS or tetramethylsilane or (CH3)4 Si Topic: General, Bond Rotation, Proton Exchange 76. Name two rapid processes that occur in organic molecules. Ans: Rotation about C-C single bonds; chemical exchange of protons attached to electronegative atoms Topic: Molecular Ion 77. In electron impact mass spectrometry, a beam of high-energy electrons initially dislodges one electron from the compound being studied. This produces a positively charged ion called the ____________________. Ans: molecular ion Topic: Nitrogen Rule 78. What is the nitrogen rule? Ans: If the molecular ion peak is even, the molecule must contain an even number of nitrogen atoms (zero is an even number). If the molecular ion peak is odd, the molecule must contain an odd number of nitrogen atoms.) Topic: Relative Abundance 79. What can be determined from the relative abundance of the M+• +1 peak? Ans: An approximation for the number of carbon atoms in the molecule. Topic: Relative Abundance 80. What can be determined from the relative abundance of the M+• +2 peak? Ans: The presence of a number of different elements, including S, Br, and Cl. 309 Chapter 9 Topic: Base Peak 81. In mass spectrometry, the most intense peak is assigned an intensity of 100%, and is referred to as the ______________. Ans: base peak Topic: m/z Ratio 82. A mass spectrometer sorts ions on the basis of their _______________. Ans: mass to charge ratio Topic: Structure Elucidation 83. Briefly explain how you might distinguish between the following substances by comparing their 1H-NMR spectra: O O O O I II Ans: The main difference would likely be in the chemical shift of the methine proton of the isopropyl group. The methine proton in I is likely to be more deshielded, and produce a signal (septet) at about 3.5 ppm, while the analogous proton in II is likely to be found, also as a septet, at about 2.3 ppm. O O O O I ~3.5 ppm II ~2.3 ppm 310 Chapter 9 Topic: Structure Elucidation 84. Briefly explain how you might distinguish between the following substances by comparing their 1H-NMR spectra: O O O O I II Ans: The main difference would likely be in the chemical shifts of the methine proton of the isopropyl group and the methylene proton closest to the ester function. The methine proton in I is likely to be more deshielded, and produce a signal (septet) at about 3.5 ppm, while the analogous proton in II is likely to be found, also as a septet, at about 2.3 ppm. By contrast, the methylene proton in II is likely to be more deshielded, and produce a signal (triplet) at about 3.4 ppm, while the analogous proton in II is likely to be found, also as a triplet, at about 2.2 ppm. I II O O O O ~3.5 ppm (septet) ~2.2 ppm (triplet) ~2.3 ppm (septet) ~3.4 ppm (triplet) 311 Chapter 9 Topic: Structure Elucidation 85. Briefly explain how you might distinguish between the following substances by comparing their 1H-NMR spectra: O H N N H O I II Ans: The main difference would likely be in the chemical shifts of the methine proton of the isopropyl group and the methylene proton closest to the amide function. The methine proton in I is likely to be more deshielded, and produce a signal (septet) at about 3.5 ppm, while the analogous proton in II is likely to be found, also as a septet, at about 2.3 ppm. By contrast, the methylene proton in II is likely to be more deshielded, and produce a signal (triplet) at about 3.4 ppm, while the analogous proton in II is likely to be found, also as a triplet, at about 2.2 ppm. I II O N H ~3.2 ppm (septet) ~2.2 ppm (triplet) H N O ~2.3 ppm (septet) ~3.1 ppm (triplet) 312 Chapter 9 Topic: Structure Elucidation 86. An unknown compound, A, has the formula C7H14O. Elucidate the structure of A by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. Ans: O 4-Heptanone 313 Chapter 9 Topic: Structure Elucidation 87. An unknown compound, C, has the formula C7H7Br. Elucidate the structure of C by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. 314 Chapter 9 Ans: Br 4-Bromotoluene 315 Chapter 9 Topic: Structure Elucidation 88. An unknown compound, E, has the formula C6H12O. Elucidate the structure of E by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. Ans: O 2-Hexanone 316 Chapter 9 Topic: Structure Elucidation 89. An unknown compound, F, has the formula C3H6O2. Elucidate the structure of F by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. 317 Chapter 9 Ans: O OH Propanoic acid 318 Chapter 9 Topic: Structure Elucidation 90. An unknown compound, I, has the formula C3H7NO2. Elucidate the structure of I by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. Ans: NO2 1-Nitropropane 319 Chapter 9 Topic: Structure Elucidation 91. An unknown compound, L, has the formula C5H10O2. Elucidate the structure of L by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. O Ans: O Methyl butyrate 320 Chapter 9 Topic: Structure Elucidation 92. An unknown compound, U, has the formula C6H4Cl2O. Elucidate the structure of U by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. 321 Chapter 9 OH Ans: Cl Cl 2,6-dichlorophenol 322 Chapter 9 Topic: Structure Elucidation 93. An unknown compound, V, has the formula C8H10O. Elucidate the structure of V by scrutinizing its IR, 1H NMR and 13C NMR spectra, shown below. 323 Chapter 9 Ans: OH 2,6-dimethylphenol 324 Chapter 9 Topic: Structure Elucidation 94. Examine the 1H NMR spectrum of 1-nitropropane, shown below. Assign the signals to the respective hydrogen atoms in the molecule. 4.3 ppm triplet Ans: > > > 1.0 ppm triplet NO2 2.0 ppm sextet Topic: 1H NMR 95. Predict the 1H NMR spectrum of 2-chloroethanal, CH2ClCHO. 9-10 ppm triplet Ans: > > Cl O 4-5 ppm doublet 325 Chapter 9 Topic: 1H NMR 96. Predict the number of signals in the 1H NMR spectrum of 2-methyl-2-pentanol. Ans: Five 1 2 1' 4 3 OH 5 Topic: 13C NMR, Structure Elucidation 97. Interpret the following 13C/DEPT spectrum of a compound C5H10Br2: elucidate the structure and assign all the 13C resonances. 32 ppm > > 33 ppm > > Br 27 ppm Br > Ans: 33 ppm 326 Chapter 9 Topic: 1H NMR 98. Predict the 1H NMR spectrum of diethoxymethane, CH3CH2OCH2OCH2CH3. ~1.2 ppm triplet ~1.2 ppm triplet > > ~3.4 ppm quartet ~4.9 ppm singlet > O > O > Ans: ~3.4 ppm quartet 327 Chapter 10 MULTIPLE CHOICE QUESTIONS Topic: Delta H Calculations and Comparisons 1. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. (CH3)3C-H + Cl-Cl (CH3)3C-Cl + H-Cl ΔHo=400 kJ/mol ΔHo=243 kJ/mol A) B) C) D) E) ΔHo=349 kJ/mol ΔHo=432 kJ/mol +243 kJ / mol -138 kJ / mol +138 kJ / mol -781 kJ / mol +781 kJ / mol Ans: B Topic: Delta H Calculations and Comparisons 2. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. CH3CH2CH2-H + Br-Br CH3CH2CH2-Br ΔHo=423 kJ/mol ΔHo=193 kJ/mol A) B) C) D) E) + H-Br ΔHo=294 kJ/mol ΔHo=366 kJ/mol +616 kJ / mol -101 kJ / mol -173 kJ / mol +57 kJ kJ / mol -44 kJ / mol Ans: E 328 Chapter 10 Topic: Delta H Calculations and Comparisons 3. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. CH3CH2-H + Cl-Cl CH3CH2-Cl + H-Cl ΔH =421 kJ/mol ΔH =243 kJ/mol o A) B) C) D) E) ΔH =353 kJ/mol ΔH =432 kJ/mol o o o -121 kJ / mol +121 kJ / mol +243 kJ / mol +664 kJ / mol -785 kJ / mol Ans: A Topic: Delta H Calculations and Comparisons 4. The bond dissociation energies for the relevant bonds are given below each of the species involved in the following reaction. Calculate the overall ΔH° for the reaction. (CH3)2CH-H + F-F (CH3)2CH-F + H-F ΔHo=413 kJ/mol ΔHo=159 kJ/mol A) B) C) D) E) ΔHo=439 kJ/mol ΔHo=570 kJ/mol +437 kJ / mol -437 kJ / mol -411 kJ / mol +26 kJ / mol -1581 kJ / mol Ans: B Topic: Delta H Calculations and Comparisons 5. A) B) C) D) E) Which of the reactions listed below would have a value of ΔH° equal to zero? H–H ⎯⎯⎯⎯→ 2H· H· + CH3–H ⎯⎯⎯⎯→ CH3–H + H· CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 CH3· + CH3–H ⎯⎯⎯⎯→ CH3–H + CH3· Reactions (B) and (D) Ans: E 329 Chapter 10 Topic: Delta H Calculations and Comparisons 6. A) B) C) D) E) Which of the reactions listed below would be exothermic? CH3–CH3 ⎯⎯⎯⎯→ 2CH3· CH3· + CH4 ⎯⎯⎯⎯→ CH4 + CH3· 2(CH3)2CH· ⎯⎯⎯⎯→ (CH3)2CH–CH(CH3)2 H· + (CH3)3CH ⎯⎯⎯⎯→ (CH3)3CH + H· None of the above Ans: C Topic: Delta H Calculations and Comparisons 7. A) B) C) D) E) Which of the reactions listed below would be exothermic? H–H ⎯⎯⎯⎯→ 2H· H· + CH3–H ⎯⎯⎯⎯→ CH3–H + H· CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 CH3· + CH3–H ⎯⎯⎯⎯→ CH3–H + CH3· All of the above Ans: C Topic: Activation Energies 8. Which reaction would you expect to have the smallest energy of activation? ΔH°(kJ mol-1) A) CH3· + CH3· ⎯⎯⎯⎯→ CH3CH3 -378 B) CH4 + F· ⎯⎯⎯⎯→ CH3· + HF -130 C) CH4 + I· ⎯⎯⎯⎯→ CH3· + HI +142 D) CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr +104 E) CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl +8 Ans: A Topic: Activation Energies 9. A) B) C) D) E) Which of the following reactions would have an activation energy equal to zero? CH3–CH3 ⎯⎯⎯⎯→ 2CH3· H· + CH3CH3 ⎯⎯⎯⎯→ CH3CH3 + H· 2CH3CH2· ⎯⎯⎯⎯→ CH3CH2CH2CH3 CH3· + CH3CH3 ⎯⎯⎯⎯→ CH3CH3 + CH3· None of the above Ans: C 330 Chapter 10 Topic: Activation Energies 10. A) B) C) Which of the following reactions would have the smallest energy of activation? CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr CH3CH3 + Br· ⎯⎯⎯⎯→ CH3CH2· + HBr CH3CHCH3 CH3CHCH2 + + Br CH3 D) CH3CHCH3 CH3CCH3 + E) + Br CH3 CH3 CH3 C HBr CH3 HBr CH3 CH3 CH3 + Br CH3 CH3 C CH2 + HBr CH3 Ans: D Topic: Activation Energies 11. Which of the following reactions would have the smallest energy of activation? . A) + Br . + HBr B) + HBr . + Br . C) + Br . D) + Br . E) + HBr . . + HBr . + HBr + Br . Ans: C Topic: Activation Energies 12. A) B) C) D) E) An example of a reaction having an Eact = 0 would be: Br· + Br–Br ⎯⎯⎯⎯→ Br–Br + Br· F· + CH4 ⎯⎯⎯⎯→ H–F + CH3· CH3· + CH3CH3 ⎯⎯⎯⎯→ CH4 + CH3CH2· Br· + H–Br ⎯⎯⎯⎯→ H–Br + Br· CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 Ans: E 331 Chapter 10 Topic: Activation Energies 13. A) B) C) Which of the following reactions should have the smallest energy of activation? CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl CH3CH3 + Cl· ⎯⎯⎯⎯→ CH3CH2· + HCl CH3CHCH3 CH3CHCH2 + + Cl CH3 D) CH3CHCH3 CH3CCH3 + E) + Cl CH3 CH3 CH3 C HCl CH3 HCl CH3 CH3 CH3 + CH3 Cl CH3 C CH2 + CH3 Ans: D Topic: Activation Energies 14. Which reaction would you expect to have the largest energy of activation? ΔH° (kJ mol-1) A) CH3· + CH3· ⎯⎯⎯⎯→ CH3CH3 -378 B) CH3· + Br· ⎯⎯⎯⎯→ CH3Br -130 C) CH4 + I· ⎯⎯⎯⎯→ CH3· + HI +142 D) CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr +104 E) CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl +8 Ans: C Topic: Activation Energies 15. A) B) C) D) E) An example of a reaction having an Eact = 0 would be: Br· + Br–Br ⎯⎯⎯⎯→ Br–Br + Br· F· + CH4 ⎯⎯⎯⎯→ H–F + CH3· CH3· + Cl· ⎯⎯⎯⎯→ CH3Cl More than one of these None of these Ans: C 332 HCl Chapter 10 Topic: Activation Energies 16. A) B) C) D) E) Which of the following reactions would have an activation energy equal to zero? H–H ⎯⎯⎯⎯→ 2H· H· + CH3–H ⎯⎯⎯⎯→ CH3––H + H· CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 CH3· + CH3–H ⎯⎯⎯⎯→ CH3–H + CH3· All of the above Ans: C Topic: Activation Energies 1. Given the following bond dissociation energies: ΔH° (kJ mol-1) CH3CH2–H H–F H–Cl H–Br H–I A) B) C) D) E) Ans: 421 570 432 366 298 predict which of the following reactions would have the highest energy of activation. CH3CH3 + F· ⎯⎯⎯⎯→ CH3CH2· + HF CH3CH3 + Cl· ⎯⎯⎯⎯→ CH3CH2· + HCl CH3CH3 + Br· ⎯⎯⎯⎯→ CH3CH2· + HBr CH3CH3 + I· ⎯⎯⎯⎯→ CH3CH2· + HI ΔH° values are important, but not sufficient for this prediction D 333 Chapter 10 Topic: Activation Energies 18. Given the following bond dissociation energies: ΔH°(kJ mol-1) CH3–H H–F H–Cl H–Br H–I A) B) C) D) E) 440 570 432 366 298 predict which of the following reactions would have the highest energy of activation. CH4 + F· ⎯⎯⎯⎯→ CH3· + HF CH4 + Cl· ⎯⎯⎯⎯→ CH3· + HCl CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr CH4 + I· ⎯⎯⎯⎯→ CH3· + HI ΔH° values are important, but not sufficient for this prediction Ans: D Topic: Activation Energies 19. A) B) C) D) E) For which of the following gas-phase reactions would the Eact be equal to ΔH°? Cl–Cl ⎯⎯⎯⎯→ 2Cl· 2 Cl· ⎯⎯⎯⎯→ Cl–Cl Cl· + CH4 ⎯⎯⎯⎯→ CH3· + H–Cl CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 CH3· + Cl–Cl ⎯⎯⎯⎯→ CH3–Cl + Cl· Ans: A Topic: Reaction Products (Isomers) 20. In the presence of light, ethane (1 mol) reacts with chlorine (1 mol) to form which product(s)? A) CH2ClCHCl2 B) CH3CHCl2 C) CH3CH2Cl D) ClCH2CH2Cl E) All of these Ans: E 334 Chapter 10 Topic: Reaction Products (Isomers) 21. How many different monochlorobutanes (including stereoisomers) are formed in the free radical chlorination of butane? A) 1 B) 2 C) 3 D) 4 E) 5 Ans: C Topic: Reaction Products (Isomers) 22. The reaction of 2-methylbutane with chlorine would yield how many monochloro derivatives? (include stereoisomers) A) 2 B) 3 C) 4 D) 5 E) 6 Ans: E Topic: Reaction Products (Isomers) 23. The reaction of 2,2-dimethylbutane with chlorine would yield how many monochloro derivatives? (include stereoisomers) A) 1 B) 2 C) 3 D) 4 E) 5 Ans: D Topic: Reaction Products (Isomers) 24. The free radical chlorination of pentane produces this number of monochloro compounds, including stereoisomers. A) 2 B) 3 C) 4 D) 5 E) 6 Ans: C 335 Chapter 10 Topic: Reaction Products (Isomers) 25. A) B) C) D) E) Free radical chlorination will produce but one monochloro derivative in the case of: Propane. Butane. Isobutane. Isopentane. Neopentane. Ans: E Topic: Reaction Products (Isomers) 26. Free radical chlorination of hexane produces this number of monochloro derivatives (including stereoisomers): A) 3 B) 4 C) 5 D) 7 E) 8 Ans: C Topic: Reaction Products (Isomers) 27. More than one monochloro compound can be obtained from the free radical chlorination of: A) Cyclopentane B) Neopentane C) Isobutane D) Ethane E) Methane Ans: C Topic: Reaction Products (Isomers) 28. What is the total number of trichloropropanes which can be produced by free radical chlorination of propane? Include all stereoisomers. A) 4 B) 5 C) 6 D) 7 E) 8 Ans: C 336 Chapter 10 Topic: Reaction Products (Isomers) 29. If chlorocyclopentane were chlorinated to form all possible dichloro compounds and the product mixture subjected to precise fractional distillation, how many fractions would be obtained (ideally)? A) 3 B) 4 C) 5 D) 7 E) 9 Ans: C Topic: Reaction Products (Isomers) 30. The free radical chlorination of (R)-2-chloropentane forms a mixture of dichloropentanes which includes: A) three optically active compounds B) two achiral compounds. C) two meso compounds. D) one pair of diastereomers. E) one racemic mixture. Ans: B Topic: Reaction Products (Isomers) 31. How many monochloro derivatives, including stereoisomers, can be formed in the chlorination of 1-bromobutane? A) 4 B) 5 C) 6 D) 7 E) 8 Ans: D Topic: Reaction Products (Isomers) 32. The free radical chlorination of 3-chloropentane forms a mixture of dichloropentanes which, on precise fractional distillation, affords these fractions: A) 4 fractions, none optically active B) 4 fractions, 2 optically active C) 7 fractions, 4 optically active D) 7 fractions, 6 optically active E) 7 fractions, all optically active Ans: A 337 Chapter 10 Topic: Reaction Products (Isomers) 33. Consider the light-initiated chlorination of (S)-2-chlorobutane followed by careful fractional distillation (or separation by GLC) of all of the products with the formula C4H8Cl2. How many fractions (in total) would be obtained and how many of these fractions would be optically active? A) Three fractions total; all optically active B) Four fractions total; three fractions optically active C) Five fractions total; all optically active D) Five fractions total; four fractions optically active E) Five fractions total; three fractions optically active Ans: E Topic: Reaction Products 34. What is the product of the reaction CH3CH2CH CH2 + CBr4 peroxides A) CH3CH2CH=CHCBr3 B) CH3CH2CHCH2CBr3 Br C) CH3CH2CHCH2Br CBr3 D) CH3CH2CH2CH2CBr3 E) No reaction occurs. Ans: B 338 ? Chapter 10 Topic: Reaction Products 35. Select the structure of the major product formed in the following reaction. CH3 Br2 ? hν CH2Br Br CH3 CH3 Br CH3 IV V Br Br I A) B) C) D) E) II III I II III IV V Ans: B Topic: Reaction Products 36. What would be the major product of the following reaction? CH3 HBr ? peroxides CH3 Br CH3 CH3 Br CH3 Br OR CH3 Br I A) B) C) D) E) II III IV I II III IV V Ans: A 339 V Chapter 10 Topic: Reaction Products 37. In the presence of light at 25°C, isobutane (1 mol) and bromine (1 mol) yield which monobromo product(s)? A) 2-Methyl-1-bromopropane (almost exclusively) B) 2-Methyl-2-bromopropane (almost exclusively) C) A mixture of 50% (A) and 50% (B) D) A mixture of 90% (A) and 10% (B) E) Butyl bromide Ans: B Topic: Reaction Products 38. Which of these molecules is not expected to arise as a product of the high temperature chlorination of methane? A) CCl4 B) HCCl3 C) CH2Cl2 D) CH3CH3 E) CH2=CH2 Ans: E Topic: Reaction Products 39. In a competition reaction, equimolar amounts of five alkanes compete for a deficiency of chlorine at 300°C. The greatest amount of reaction would occur in the case of which of these alkanes? A) Ethane B) Propane C) Butane D) Isobutane E) Pentane Ans: D Topic: Reaction Products 40. Which of the following combinations of reactants can provide a demonstrable example of anti-Markovnikov addition? A) CH2=CHCH3 + HCl + ROOR B) CH3CH=CH2 + H2O + Cl2 C) CH3CH=CHCH3 + HBr + ROOR D) CH3CH2CH=CH2 + HBr + ROOR E) CH3CH2CH=CH2 + Br2 + ROOR Ans: D 340 Chapter 10 Topic: Reaction Products 41. 2-Methyl-2-butene reacts with HBr in the presence of peroxide to give (chiefly): A) (CH3)2CHCH2CH2Br B) (CH3)2CHCHCH3 Br C) (CH3)2CCH2CH3 D) Br CH3 E) BrCH2CHCH2CH3 Br (CH3)2CCHCH3 Br Ans: B Topic: Reaction Products 42. What product would result from the following reaction? + HBr peroxides ? Br Br I A) B) C) D) E) Br HOO Br II III Br OOH IV I II III IV V Ans: A 341 V Chapter 10 Topic: Synthesis 43. Which of the following would serve as the best synthesis of 2-bromohexane? peroxides A) B) C) D) CH2 CHCH2CH2CH2CH3 + HBr CH2 CHCH2CH2CH2CH3 + HBr CH3CH2 CHCH2CH2CH3 + HBr CH3CH2 CHCH2CH2CH3 + HBr heat heat heat peroxides heat E) All of the above would be equally suitable. Ans: B Topic: Synthesis 44. Which would be the best way to carry out the following synthesis? ? (CH3)3COH (CH 3)2CHCH2Br A) B) C) D) E) (1) HA, heat; (2) HBr (1) HBr and peroxides; (2) Br2/CCl4 (1) HA, heat; (2) HBr and peroxides (1) Br2/CCl4; (2) HA, heat (1) HA, heat; (2) Br2/CCl4 Ans: C Topic: Reaction Products 45. What sequence of reactions could be used to prepare cis-1,2-cyclopentanediol from cyclopentane? A) (1) Cl2, hν; (2) t-BuOK/t-BuOH; (3) OsO4; (4) NaHSO3/H2O B) (1) t-BuOK/t-BuOH; (2) Cl2, hν; (3) NaOH/H2O C) (1) Cl2, hν; (2) t-BuOK/t-BuOH; (3) H2O2 D) (1) NaOH/H2O; (2) Br2; (3) NaNH2(2eq.)/liq.NH3; (4) KMnO4, NaOH/H2O, 5°C E) (1) Cl2, hν; (2) t-BuOK/t-BuOH; (3) Hg(OAc)2, H2O (4) NaBH4, H3O+ Ans: A 342 Chapter 10 Topic: Mechanisms 46. Carbocations are NOT intermediates in which one of the following reactions? Br A) + HBr B) OH + H2SO4 H C) H2B + BH3 OSO3H D) + H2SO4 E) R-O-O-R Br + HBr Ans: E Topic: Mechanisms 47. A) B) C) D) A chain reaction is one that: involves a series of steps. involves two steps of equal activation energy. is one that can be initiated by light. involves a series of steps, each of which generates a reactive intermediate that brings about the next step. E) involves free radicals that have an unusual stability and thereby cause a large quantum yield. Ans: D Topic: Mechanisms 48. Which of the following statements is true when used to compare the reaction of fluorine with 2-methylhexane and the reaction of bromine with 2-methylhexane? A) Bromine is the less reactive and the less selective, giving 2-bromo-2-methyl hexane as one of several products. B) Fluorine is the less reactive and the more selective, giving 2-fluoro-2-methyl hexane as the major product. C) Fluorine is the more reactive and less selective, giving 2-fluoro-2-methyl hexane as one of several products. D) Bromine is the more reactive and the more selective, giving 2-bromo-2-methyl hexane as the major product. E) More than one of the above statements is true Ans: C 343 Chapter 10 Topic: Mechanisms 49. An alternate mechanism for the chlorination of methane is: Cl2 ⎯⎯⎯⎯→ 2Cl· Cl· + CH4 ⎯⎯⎯⎯→ CH3Cl + H· H· + Cl2 ⎯⎯⎯⎯→ HCl + Cl· A) B) C) D) E) Cl–Cl, ΔH° = 243 kJ mol-1 CH3–H, ΔH° = 440 kJ mol-1 CH3–Cl, ΔH° = 352 kJ mol-1 H–Cl, ΔH° = 432 kJ mol -1 This mechanism is unlikely because: The overall ΔH° is highly endothermic. The probability factor is low. One of the chain propagating steps is non-productive. One of the chain propagating steps has a very high Eact. One of the chain propagating steps is highly exothermic. Ans: D Topic: Mechanisms 50. A) B) C) D) E) Which statement(s) is(are) true about the reaction of bromine with isobutane? Bromine selectively abstracts the tertiary hydrogen. The transition state of the rate determining step is product-like. The major product formed from this reaction is 1-bromo-2-methylpropane. A) and B) A), B) and C) Ans: D Topic: Mechanisms 51. A) B) C) For which reaction would the transition state be most product-like? CH4 + Br· ⎯⎯⎯⎯→ CH3· + HBr CH3CH3 + Br· ⎯⎯⎯⎯→ CH3CH2· + HBr CH3CHCH3 CH3CHCH2 + + Br CH3 D) CH3CHCH3 CH3CCH3 + E) + Br CH3 CH3 CH3CCH3 HBr CH3 HBr CH3 CH3 + CH3CCH2 Br CH3 CH3 Ans: A 344 + HBr Chapter 10 Topic: Mechanisms 52. For which of the following reactions would the transition state most resemble the products? The following bond dissociation energies may be useful. (CH3)2CH–H (413 kJ mol-1) CH3CH2CH2–H (423 kJ mol-1) H–Cl (432 kJ mol-1) H–F (570 kJ mol-1) H–Br (366 kJ mol-1) A) B) CH3CH2CH3 + F· ⎯⎯⎯⎯→ CH3CH2CH2· + HF C) D) CH3CH2CH3 + Cl· ⎯⎯⎯⎯→ CH3CH2CH2· + HCl E) CH3CH2CH3 + Br· ⎯⎯⎯⎯→ CH3CH2CH2· + HBr Ans: E Topic: Mechanisms 53. Which of the following gas-phase reactions is a possible chain-terminating step in the light-initiated chlorination of methane? A) Cl–Cl ⎯⎯⎯⎯→ 2Cl· B) Cl· + CH4 ⎯⎯⎯⎯→ CH3· + H–Cl C) CH3· + CH3· ⎯⎯⎯⎯→ CH3–CH3 D) CH3· + Cl–Cl ⎯⎯⎯⎯→ CH3Cl + Cl· E) More than one of the above Ans: C Topic: Mechanisms 54. The reaction of 1-butene with HBr in the presence of peroxides yields 1-bromobutane. The mechanism for the reaction involves: A) attack on the alkene by a Br+ ion. B) attack on the alkene by a H+ ion. C) attack on the alkene by a bromine atom, Br·. D) attack on the alkene by a hydrogen atom, H·. E) isomerization of the 2-bromobutane produced initially. Ans: C 345 Chapter 10 Topic: Mechanisms 55. The reaction of Cl2 with a methyl radical has a positive ΔH°. Which of these drawings is the best representation of the transition state of this reaction? H H A) δCl δCl C H H B) Cl Cl C H H C) δCl δC Cl H H H D) Cl E) H + δCl Cl Cl C δC H H H H H Ans: E Topic: Free Radicals 56. A) B) C) D) E) Ans: The hybridization state of the carbon of a methyl radical is: sp sp2 sp3 sp4 p3 B Topic: Free Radicals 57. A) B) C) D) E) The p-orbital of a methyl radical carbon, CH3·, contains how many electrons? 1 2 3 4 0 Ans: A 346 Chapter 10 Topic: Free Radicals 58. Which of the following free radicals is the most stable? CH2 A) B) CH3CHCH2CH3 CH3 C) CH3CHCH2CH2 CH3 D) CH2CHCH2CH3 CH3 CH3CHCHCH3 E) CH3 CH3CCH2CH3 Ans: E Topic: Free Radicals 59. Hydrogen atom abstraction from which position would yield the most stable free radical intermediate during the reaction of bromine with 2,2,3-trimethylpentane? A) C1 B) C2 C) C3 D) C4 E) C5 Ans: C Topic: Free Radicals 60. A) B) C) D) E) Free radicals can be produced by: use of high temperatures. irradiation with light. reaction of a molecule with another free radical. both A) and B). all of A), B) and C). Ans: E 347 Chapter 10 Topic: Free Radicals 61. The ΔH° value is expected to be least for which indicated C-H bond of isopentane? A) H CH2CHCH2CH3 B) C) CH3 CH3CHCH2CH3 CH2 H H CH3CCH2CH3 D) CH3 H CH3CHCHCH3 E) CH3 CH3CHCH2CH2 H CH3 Ans: C Topic: Free Radicals 62. A) B) C) D) E) Which is true for a chain-terminating step? A new free radical is formed. The process is endothermic. Eact = 0. ΔH° is positive. A product is formed which is immune to further reaction. Ans: C Topic: Free Radicals 63. At some temperatures, the relative reactivities of 3°, 2° and 1° alkane hydrogens in free radical chlorination are in the ratio of 5:3:1. Thus, monochlorination of isopentane should produce these percentages of 2-chloro-2-methylbutane (A), combined 1-chloro2-methylbutane and 1-chloro-3-methylbutane (B), and 2-chloro-3-methylbutane (C): A) 8% A, 75% B, 17% C B) 25% A, 45% B, 30% C C) 29% A, 44% B, 18% C D) 30% A, 35% B, 35% C E) 36% A, 43% B, 21% C Ans: B 348 Chapter 10 Topic: Miscellaneous 64. According to the present explanation of the role of atmospheric chlorofluorocarbons in ozone depletion, it is this species which destroys, i.e., reacts irreversibly with, ozone. A) F· B) Cl· C) O· D) ClO· E) FO· Ans: B Topic: Miscellaneous 65. If propene polymerization is initiated by the use of diacyl peroxide, this is an intermediate species formed early in the process. CH3 CH3 A) B) RCH2CHCH2CH CH3 CH3 C) RCHCH2CHCH2 CH3 CH3 D) RCHCH2CH2CH CH3 RCH2CHCHCH2 CH3 E) CH3 RCCH2CH CH3 CH3 Ans: A Topic: Miscellaneous 66. As the term "peroxide" is used in Chapter 10, it can refer to which structure(s)? A) ROOR B) ROOH C) O O RCOOCR D) Answers A) and B) only E) Answers A), B) and C) Ans: E 349 Chapter 10 Topic: Miscellaneous 67. When an alkane in which all hydrogen atoms are not equivalent is monosubstituted, use of this halogen produces a ratio of isomers which is essentially statistical, i.e., dependent only on the number of each type of hydrogen. A) F2 B) Cl2 C) Br2 D) I2 E) All of the above Ans: A Topic: Multistep Reactions 68. What is the final product, C, obtained via the following reaction sequence? Br2 hν A t-BuOK t-BuOH heat OH A) B) C) D) E) I I II III IV V Ans: A OH II B ii) H2O2, OH OH III i) BH3, THF − OH OH OH IV 350 C V Chapter 10 Topic: Multistep Reactions 69. What is the major product obtained from the following reaction sequence? Br2 hν A OH I A) B) C) D) E) t-BuOK t-BuOH heat B OH II i) Hg(OAc)2, H2O, THF ii) NaBH4, OH− OH OH OH OH III IV C V I II III IV V Ans: B Topic: Multistep Reactions 70. What is the major product obtained from the following reaction sequence? Br2 HBr NaSH B D A t-BuOK C peroxides t-BuOH hν heat SH SH A) B) C) D) E) I I II III IV V Ans: A SH II SH III IV 351 V Chapter 10 Topic: Multistep Reactions 71. What is the major product obtained from the following reaction sequence? Br2 HBr NaCN B A EtONa C D peroxides EtOH hν heat CN CN A) B) C) D) E) I I II III IV V Ans: C CN II CN CN III IV V Topic: Multistep Reactions 72. What is the major product obtained from the following reaction sequence? i) BH3, THF HBr t-BuOK B C A peroxides t-BuOH ii) H2O2, OH− heat OH OH OH I II III HO OH IV A) B) C) D) E) V I II III IV V Ans: E 352 Chapter 10 Topic: Multistep Reactions 73. What is the major product obtained from the following reaction sequence? Br2 hν OH A EtONa EtOH heat I I II III IV V Ans: E i) O3 ii) Zn, HOAc OH O OH A) B) C) D) E) B C O O II III O IV V SHORT ANSWER QUESTIONS Topic: General 74. Intermediates possessing unpaired electrons are called ______________. Ans: radicals or free radicals Topic: General 75. A covalent bond breaking so that each of the resulting intermediates bears a single unpaired electron is an example of __________________ bond cleavage. Ans: homolytic Topic: General 76. Bond formation is an ______________ process, and therefore ΔH° is ____________. Ans: exothermic; negative Topic: General 77. Although alkyl radicals are uncharged, the carbon bearing the odd electron is electron ___________, and alkyl groups provide a __________________ effect. Ans: deficient; stabilizing 353 Chapter 10 Topic: General 78. The mechanism for a free-radical reaction consists of three types of steps. These are: _______________ Ans: initiation, propagation, termination – or chain-initiating, chain-propagating, chainterminating Topic: General 79. In a chain-initiating step, radicals are _____________. Ans: created or formed Topic: General 80. In a chain-terminating step, radicals are ______________. Ans: used up or removed Topic: General 81. In a chain-propagating step, one radical _______________. Ans: generates another Topic: General 82. While the electrophilic addition of HBr to an alkene is ionic and follows Markovnikov's rule, if the reaction is done in the presence of peroxides it becomes a ___________ reaction and is ____________________ in regiochemistry. Ans: radical or free-radical; anti-Markovnikov Topic: General 83. Macromolecules made up of many repeating subunits are called ____________. Ans: polymers Topic: General 84. Two radicals that are very important in biological processes are ________________ and __________________. Ans: molecular oxygen; nitric oxide 354 Chapter 10 Topic: General 85. Chlorofluorocarbons, or freons, diffuse into the upper atmosphere. There, ultraviolet light initiates a radical chain reaction that has been shown to cause extreme damage to _______________. Ans: the ozone layer Topic: General 86. Unsymmetrical alkenes give Markovnikov products through the most stable_______________ intermediates and anti-Markovnikov products through the most stable _______________ intermediates. Ans: Carbocation; free-radical Topic: Reaction Products ( Isomers) 87. Draw bond-line formulas of all monochloro derivatives that might be formed when 2,3dimethylbutane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Cl Ans: Cl2, hν Cl * + 2,3-dimethylbutane monochloro derivatives Topic: Reaction Products ( Isomers) 88. Draw bond-line formulas of all monochloro derivatives that might be formed when 1,1dimethylcyclobutane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans: Cl2, hν Cl + Cl * + Cl 1,1-dimethylcyclobutane monochloro derivatives 355 Chapter 10 Topic: Reaction Products ( Isomers) 89. Draw bond-line formulas of all monochloro derivatives that might be formed when 3ethylhexane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans: Cl Cl2 * * + + * Cl * * hν Cl 3-ethylhexane Cl * Cl + * ** * Cl + Cl monochloro derivatives * Topic: Structure Elucidation 90. Deduce the structure of a substance, C8H18, which gives only a single monochloro derivative upon reaction with Cl2 under UV irradiation. Cl Ans: Cl2 hν single C8H18 monochloro derivative Topic: Reaction Products ( Isomers) 91. Draw bond-line formulas of all dichloro derivatives that might be formed when 1chloro-2,2,3,3,-tetramethylpentane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Cl Ans: Cl * Cl Cl2 Cl + Cl + hν Cl Cl 1-chloro-2,2,3,3tetramethylpentane Cl Cl Cl + Cl dichloro derivatives 356 * + Chapter 10 Topic: Reaction Products ( Isomers) 92. Draw bond-line formulas of all monochloro derivatives that might be formed when 2,2,4-trimethylpentane is allowed to react with Cl2 under UV irradiation. For each structure, indicate, with an asterisk, any stereocenters that might be present. Ans: Cl2 * + Cl hν Cl 2,2,4-trimethylpentane + Cl + * monochloro derivatives Cl Topic: Multistep Reactions 93. Complete the following reaction sequence: indicate regiochemical/stereochemical details as relevant. i) Br2, hν Methylcyclopentane ii) C2H5ONa/C2H5OH, heat ? iii) BH3, THF iv) H2O2, OH− Ans: Br Br2 hν C2H5ONa C2H5OH heat BH3, THF H3C H H3C H OH + H H H2O2, OH OH − H3C H H3C H BH2 357 + H H BH2 Chapter 10 Topic: Multistep Reactions 94. Complete the following reaction sequence: indicate regiochemical/stereochemical details as relevant. i) Br2, hν ii) C2H5ONa/C2H5OH, heat ? iii) HBr, peroxides iv) NaCN Br2 C2H5ONa Ans: HBr NaCN Br peroxides C2H5OH hν Br heat CN Topic: Multistep Reactions 95. Complete the following reaction sequence: indicate regiochemical/stereochemical details as relevant. i) Br2, hν ii) C2H5ONa/C2H5OH, heat 1,1,2-trimethylcyclohexane ? iii) Ozonolysis O Ans: Br2 C H ONa Ozonolysis hν Br 2 5 C2H5OH heat Topic: Multistep Synthesis 96. Suggest a reasonable strategy for the synthesis of 1-bromo-2-methylcyclohexane from methylcyclohexane Br2 C2H5ONa Ans: HBr Br peroxides C2H5OH hν Br heat 358 O Chapter 10 Topic: Mechanisms 97. Provide a reasonable mechanistic explanation for the formation of small amounts of 3,3,4,4-teramethylhexane during the free-radical bromination of 2-methylbutane. Ans: During the free radical bromination of 2-methylbutane, the most stable intermediate is produced by abstraction of the tertiary hydrogen atom at C2. Two such radicals can couple together via a termination step to afford 3,3,4,4teramethylhexane as a minor product. Br2 minor product hν + termination step: radical coupling Topic: Mechanisms 98. What product(s) might be obtained via chain-termination step(s) during the reaction of 2-methylpropene with HBr in presence of peroxides? Ans: The addition of HBr to 2-methylpropene takes place via the formation of the most stable free radical intermediate, by addition of a bromine atom at C1. Two such radicals can couple together via a termination step to afford 1,4-dibromo-2,2,3,3teramethylbutane as a minor product. Analogous coupling between this radical and a bromine radical leads to the formation of 1,2-dibromo-2-methylpropane as another minor product. HBr peroxides Br + Br most stable radical intermediate Br Br Br Br Br + Br Br termination steps: radical coupling 359 Chapter 10 Topic: Reactivity / Selectivity 99. Briefly, but clearly, explain the following observation: While alkanes can be fluorinated, chlorinated and brominated easily, they do not easily undergo iodination. Ans: The energy of activation for the first propagation step in the free radical mechanism for halogenation of alkanes determines the overall reactivity pattern for the various halogens. In contrast to the reaction with the other halogens, hydrogen atom abstraction from an alkane by an iodine atom has a very high energy of activation- since this is the first propagation step, the overall process is affected as well and iodination does not occur to any appreciable extent. I . + R-H Æ H-I + R . Eact for this step very high: reaction very slow, further steps inhibited Topic: Reactivity / Selectivity 100. Briefly, but clearly, explain the following observation: When 2-methylbutane reacts with Cl2/hν, the monochlorinated products consist of four constitutional isomers in significant yields. However, when the same alkane is allowed to react with Br2/ hν, there is only one major monobromination product. Ans: The final product distribution is a consequence of the relative ease of hydrogen atom abstraction from primary, secondary and tertiary positions. Chlorine is highly reactive and therefore there is not much differentiation between the different kinds of hydrogen atoms- as a result, all the possible free radicals are formed, leading to the formation of all possible constitutional isomers. Bromine is less reactive and more selective than chlorine in its reaction with alkanes; this results in the selective abstraction of the tertiary hydrogen atom at C2, to give the most stable radical intermediate, a tertiary radical, leading to the selective formation of only one major monobromination product. Br Br2 hν Cl2, hν Cl Cl Cl Cl 360 Chapter 11 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. What is the correct IUPAC name for the following compound? CH3 CH3CHOHCHCHCH(CH3)2 A) B) C) D) E) CH3 4-isopropyl-3,4-dimethyl-2-butanol 2,3,4-trimethyl-4-pentanol 1,1,2,3-tetramethyl-4-pentanol 3,4,5-trimethyl-2-hexanol 3,4,5,5-tetramethyl-2-pentanol Ans: D Topic: Nomenclature 2. A) B) C) D) E) A correct IUPAC name for isobutyl alcohol is: 2-Methyl-1-propanol 2-Methyl-1-butanol 1-Methyl-1-propanol 1,1-Dimethyl-1-ethanol 3-Methyl-1-propanol Ans: A Topic: Nomenclature 3. What is the correct IUPAC name for the following compound? CH3 CH3CH2C=CCH2CH3 A) B) C) D) E) CH2CH2OH 3-methyl-4-ethyl-3-hexen-6-ol 4-ethyl-3-methyl-3,6-hexenol 3-ethyl-4-methyl-3-hexen-1-ol 3-methyl-4-(2-hydroxyethyl)-3-hexene 3-(2-hydroxyethyl)- 3-methyl-3-hexene Ans: C 361 Chapter 11 Topic: Nomenclature CH3 4. CH3CCHCH A) B) C) D) E) The correct IUPAC substitutive name for 4-Penten-2-methyl-2-ol 4-Methyl-1-penten-2-ol 2-Methyl-4-penten-2-ol 4-Methyl-1-penten-4-ol 4-Hydroxy-4-methyl-1-pentene Ans: C CH3 CH2 is: Topic: Nomenclature 5. A) B) C) D) E) Which is a correct IUPAC name for CH3CH2OCH2CH2CH2OCH2CH3? 1,4-Dioxane Ethylene glycol diethyl ether 1,3-Diethoxypropane 1,2-Diethoxyethane 1,2-Diethoxymethane Ans: C Topic: Nomenclature 6. CH2CH3 CH3CH2COH A) B) C) D) E) The IUPAC name of compound 1,1,1-Triethylmethanol 1,1-Diethyl-1-propanol 2-Ethyl-3-pentanol 3-Ethyl-3-pentanol tert-Heptanol Ans: D CH2CH3 362 is: Chapter 11 Topic: Nomenclature 7. A) B) C) D) E) The correct IUPAC name for tert-butyl alcohol is: 1-Butanol 2-Methyl-1-propanol 2-Methyl-2-propanol 2-Butanol 1,1-Dimethyl-1-ethanol Ans: C Topic: Nomenclature 8. Select the structure of benzyl methyl ether. I CH3 II CH3O III CH3 O CH2 IV O CH O CH CH3 V A) B) C) D) E) CH3 CH3 CH3 CH2 O CH2 CH3 I II III IV V Ans: C 363 Chapter 11 Topic: Nomenclature 9. OH OH A) B) C) D) E) is properly named: cis-1,2-Cyclopentanediol meso-1,2-Cyclopentanediol (1R,2R)-1,2-Cyclopentanediol (1R,2S)-1,2-Cyclopentanediol (1S,2S)-1,2-Cyclopentanediol Ans: C Topic: Nomenclature 10. A) B) C) D) E) 2,2-Dimethyl-1-propanol has the common name: Isoamyl alcohol Isopentyl alcohol tert-Pentyl alcohol Neopentyl alcohol 2-Methylisobutyl alcohol Ans: D Topic: Nomenclature 11. What is the most accurate name for the molecule represented by the following Fischer projection formula? H H3CH2C A) B) C) D) E) OCH3 CH3 sec-Butyl methyl ether Isobutyl methyl ether tert-Butyl methyl ether (R)-2-Methoxybutane (S)-2-Methoxybutane Ans: E 364 Chapter 11 Topic: Nomenclature 12. A correct name for the following Fischer projection formula is: OH CH3 C C C CH3 H A) B) C) D) E) (R)-3-Pentyn-2-ol (S)-3-Pentyn-2-ol (R)-2-Pentyn-4-ol (S)-2-Pentyn-4-ol (S)-2-Hydroxy-3-pentyne Ans: B Topic: Nomenclature 13. A) B) C) D) E) Which of these, though commonly used, is an incorrect name for CH3CHOHCH3? Isopropyl alcohol sec-Propyl alcohol 2-Propanol Isopropanol More than one of these. Ans: D Topic: Nomenclature 14. A) B) C) D) E) Which of these, though commonly used, is an incorrect name for (CH3)3COH? tert-Butyl alcohol tert-Butanol 2-Methyl-2-propanol More than one is incorrect. Each is a correct name. Ans: B Topic: Isomerism, Stereoisomers 15. A) B) C) D) E) Which of the following can be described as “optically active, primary alcohol”? CH3CH2CH2CH2CH2OH (CH3)2CHCH2CH2OH CH3CH2CH(CH3)CH2OH (CH3)2CHCHOHCH3 Two of the above Ans: C 365 Chapter 11 Topic: Isomerism, Stereoisomers 16. A) B) C) D) E) What is the total number of pentyl alcohols, including stereoisomers? 7 8 9 10 11 Ans: E Topic: Isomerism, Stereoisomers 17. The number of primary alcohols corresponding to the formula C5H12O, counting stereoisomers separately, is: A) 1 B) 2 C) 3 D) 4 E) 5 Ans: E Topic: Isomerism, Stereoisomers 18. The number of optically active pentyl alcohols (C5H12OH), i.e., the total number of individual enantiomers, is: A) 0 B) 2 C) 3 D) 4 E) 6 Ans: E Topic: Alcohol Reactions 19. Which of the following reactions would serve as a synthesis of butyl bromide? reflux A) CH CH CH CH OH + HBr 3 2 2 2 B) CH3CH2CH2CH2OH + PBr3 ⎯⎯⎯⎯⎯→ reflux C) CH CH CH CH OH + NaBr 3 2 2 2 D) CH3CH2CH2CH2OH + Br2 ⎯⎯⎯⎯⎯→ E) Answers A) and B) only Ans: E 366 Chapter 11 Topic: Ether Reactions 20. The product(s) of the following reaction CH2 CH2 excess HBr CH2 CH2 is/are: heat O CH3CH2OCH2CH3 CH3CH2CH2CH2OH and CH3CH2CH2CH2Br I II CH2 BrCH2CH2CH2CH2OH and BrCH2CH2CH2CH2Br CH2 CH2 O III A) B) C) D) E) IV I II III IV None of these Ans: C 367 CHBr Chapter 11 Topic: Alcohol Synthesis 21. Which product(s) would you expect to obtain from the following sequence of reactions? CH3 1. BH3-THF ? 2. H2O2, NaOH CH3 CH3 O OH OH + enantiomer I A) B) C) D) E) H3C CH3 II OH + enantiomer + enantiomer III IV I II III IV V Ans: C Topic: Alcohol Synthesis 22. Which would be the best way to carry out the following synthesis? ? CH3CH2CHCH3 CH3CH2CH2CH2OH Br A) B) C) D) E) CH2OH (1) HA, heat; (2) H3O+, H2O, heat (1) (CH3)3COK / (CH3)3COH; (2) BH3:THF, then H2O2, OH(1) (CH3)3COK / (CH3)3COH; (2) H3O+, then H2O, heat (1) KOH, C2H5OH; (2) BH3:THF, then H2O2, OH(1) KOH, C2H5OH; (2) HA, heat; (3) H3O+, H2O, heat Ans: B 368 V Chapter 11 Topic: Alcohol Synthesis 23. Select the structure of the major product formed from the following reaction. CH3 1. Hg(OOCCH3)2 THF, H2O ? 2. NaBH4, NaOH CH3 CH3 CH2OH HO CH3 OH CH3 OH OH I A) B) C) D) E) II III IV I II III IV V Ans: D 369 V Chapter 11 Topic: Alcohol Synthesis, Isotope Labeling 24. The hydroboration-oxidation procedure can be successfully employed for synthesis of deuterated derivatives, by using BD3 instead of BH3. What product would you expect from the following reaction? CH3 1. (BD3)2 ? 2. H2O2/NaOH HO H D H CH3 + enantiomer I A) B) C) D) E) H D BD2 CH3 + enantiomer II D D CH3 H + enantiomer III H OH CH3 H D + enantiomer IV I II III IV V Ans: A Topic: Ether Reactions, Isotope Labeling 25. Select the structure of the major product formed in the following reaction. HA CH3CH CH2 ? 18 O H2 O 18 A) CH3CH2CH2 OH B) CH3CHCH3 C) 18OH CH3CHCH2OH 18OH D) CH3CH E) CH2 OH 18OH CH3CHCH218OH 18OH Ans: C 370 BD2 CH3 + enantiomer V Chapter 11 Topic: Ether Reactions 26. What would be the major product of the following reaction Concd. HBr (xs) C6H5CH2OCH3 A) B) C) D) E) ? heat C6H5Br + CH3OH C6H5CH2Br + CH3Br C6H5CH2OH + CH3Br C6H5CH2Br + CH3OH C6H5CH2CH2Br Ans: B Topic: Ether Synthesis 27. A) B) C) D) E) Which is the best way to prepare 3-methoxypentane via the Williamson method? CH3OH + CH3CH2CHOHCH2CH3 + H2SO4, 140°C CH3OH + (CH3)2CHCH2CH2OH + H2SO4, 140°C CH3ONa + (CH3CH2)2CHBr CH3I + (CH3CH2)2CHONa CH3I + (CH3)2CHCH2CH2ONa Ans: D Topic: Ether Synthesis 28. A) B) C) D) E) Which is the best method to prepare 2-ethoxy-5methylhexane? C2H5ONa + (CH3)2CHCH2CH2Br C2H5ONa + (CH3)2CHCH2CH2CH2CH2Br C2H5ONa + (CH3)2CHCH2CH2CHBrCH3 C2H5Br + (CH3)2CHCH2CH2CH(CH3)ONa C2H5OH + (CH3)2CHCH2CH2CHOHCH3 + H2SO4, 140°C Ans: D Topic: Alcohol Reactions 29. A) B) C) D) E) Which of the following could be used to synthesize 2-bromobutane? CH3CH2C=CH2 + Br2 (aq) ⎯⎯⎯⎯→ CH3CH2CΗΟΗCH3 + HBr ⎯⎯⎯⎯→ CH3CH2C≡CH + HBr ⎯⎯⎯⎯→ CH3CH2C≡CH + Br2 ⎯⎯⎯⎯→ More than one of the above Ans: B 371 Chapter 11 Topic: Alcohol Reactions 30. A) B) C) D) E) Which of the following could not be used to synthesize 2-bromopentane efficiently? 1-Pentene + HBr Æ 2-Pentene + HBr Æ 2-Pentanol + HBr Æ 2-Pentanol + PBr3 Æ All of the above would afford good yields of 2-bromopentane Ans: B Topic: Alcohol Reactions 31. A) B) C) D) E) Which of the following could be used to synthesize 1-bromobutane efficiently? CH3CH2CH=CH2 + HBr ⎯⎯⎯⎯→ CH3CH2CH2CH2OH + PBr3 ⎯⎯⎯⎯→ CH3CH2CH2CH2OH + HBr ⎯⎯⎯⎯→ CH3CH2CH2CH2OH + Br2 ⎯⎯⎯⎯→ More than one of these Ans: E Topic: Alcohol Synthesis 32. Which of the following would be a reasonable synthesis of 2-butanol? A) H3O+, heat 1-Butene 1. BH3-THF B) 1-Butene 2. H2O2, NaOH 1. Hg(OAc)2, THF, H2O C) 1-Butene 2. NaBH4, NaOH D) More than one of these E) None of these Ans: D 372 Chapter 11 Topic: Epoxide Reactions 33. What would be the final product? O CH3 RCOOH CH2 H3CC product CH3OH, HA final product A) (CH3)2CHCH2OCH3 B) (CH3)2CCH3 C) OCH3 (CH3)2CCH2OH OCH3 D) (CH3)2CCH2OCH3 E) OH (CH3)2CCH2OCH3 OCH3 Ans: C Topic: Alcohol Synthesis 34. Which of the following would be a reasonable synthesis of CH3CH2CH2CH2OH? A) H3O+, heat 1-Butene 1. BH3-THF B) 1-Butene 2. H2O2, NaOH 1. Hg(OAc)2, THF, H2O C) 1-Butene 2. NaBH4, NaOH D) More than one of these E) None of these Ans: B Topic: Alcohol Synthesis 35. Which would be the best method for converting 3,3-dimethyl-1-pentene into 3,3dimethyl-2-pentanol? A) H3O+, heat B) BH3:THF; then H2O2, OHC) concd. H2SO4; then H2O, heat D) Hg(OAc)2/THF-H2O; then NaBH4,OHE) HBr; then NaOH/H2O Ans: D 373 Chapter 11 Topic: Alcohol Reactions 36. trans-3-Methylcyclopentanol is treated with CH3SO2Cl in the presence of base. The product of this reaction is then heated with KI in methanol. What is the final product? A) trans-1-Iodo-3-methylcyclopentane B) cis-1-Iodo-3-methylcyclopentane C) 1-Methylcyclopentene D) 2-Methylcyclopentene E) 3-Methylcyclopentene Ans: B Topic: Ether Synthesis 37. Which method would provide the best synthesis of ethyl isopropyl ether? A) (CH3)2CHONa + CH3CH2Br ⎯⎯⎯⎯⎯→ B) CH3CH2ONa + (CH3)2CHBr ⎯⎯⎯⎯⎯→ C) H2SO4, 140 oC CH3CH2OH + (CH3)2CHOH D) H2SO4, 180 oC CH3CH2OH + (CH3)2CHOH E) CH3CH2ONa + (CH3)2CHOH ⎯⎯⎯⎯⎯→ Ans: A Topic: Alcohol Reactions 38. A) B) C) D) E) Which of the following could be used to synthesize 1-bromopentane? CH3CH2CH2CH=CH2 + HBr ⎯⎯⎯⎯→ CH3CH2CH2CH2CH2OH + PBr3 ⎯⎯⎯⎯→ CH3CH2CH2CH2CH2OH + NaBr ⎯⎯⎯⎯→ CH3CH2CH2CH2CH2OH + Br2 ⎯⎯⎯⎯→ CH3CH2CH2CH=CH2 + Br2 ⎯⎯⎯⎯→ Ans: B 374 Chapter 11 Topic: Epoxide Reactions 39. Which compound (or compounds) would be produced when trans-2-butene is treated first with a peroxy acid to form an epoxide, and then the epoxide is subjected to acidcatalyzed hydrolysis? H HO CH3 CH3 CH3 H H OH C C C C C C H CH3 OH A) B) C) D) E) HO HO CH3 H H3C H OH I II An equimolar mixture of I and II An equimolar mixture of II and III I alone II alone III alone Ans: E III Topic: Ether Reactions 40. A) B) C) D) E) Heating 2-ethoxyhexane with excess concentrated HBr would produce: CH3CH2OCH2CH2CH2CH2CH2CH2Br BrCH2CH2OCH2CH2CH2CH2CH2CH3 CH3CH2OH and CH3CH2CH2CH2CHBrCH3 CH3CH2Br and CH3CH2CHOHCH2CH2CH3 CH3CH2Br and CH3CH2CH2CH2CHBrCH3 Ans: E Topic: Ether Synthesis 41. A) B) C) D) E) Which is the best method for the synthesis of tert-butyl methyl ether? CH3ONa + (CH3)3CBr ⎯⎯⎯⎯→ (CH3)3CONa + CH3I ⎯⎯⎯⎯→ CH3OH + (CH3)3COH + H2SO4 at 140° C ⎯⎯⎯⎯→ (CH3)3CONa + CH3OCH3 ⎯⎯⎯⎯→ CH3ONa + (CH3)3COH ⎯⎯⎯⎯→ Ans: B 375 Chapter 11 Topic: Alcohol Reactions 42. What would be the major product of the following reaction? H OH CH3SO2Cl CH3 base mesylate NaI ? ethanol H H I I CH3 A) B) C) D) E) H H H OSO2I I CH3 CH3 CH3 H H I H I II III IV I II III IV An equimolar mixture of I and II Ans: B Topic: Alcohol Reactions 43. cis-3-Methylcyclopentanol is treated with CH3SO2Cl in the presence of a base. The product of the reaction then is allowed to react with KI in methanol. What is the final product? A) trans-1-Iodo-3-methylcyclopentane B) cis-1-Iodo-3-methylcyclopentane C) 1-Methylcyclopentene D) 2-Methylcyclopentene E) 3-Methylcyclopentene Ans: A 376 Chapter 11 Topic: Alcohol Reactions 44. The major product of the following reaction would be: CH3 H OH CH3SO2Cl Product base CH3CO2- ? C2H5 CH3 H3CCO2 H C2H5 I A) B) C) D) E) CH3 CH3 H O2CCH3 H3CCO2 OSO2CH3 C2H5 C2H5 III II I II III Equal amounts of I and II None of these Ans: A 377 Chapter 11 Topic: Alcohol Synthesis 45. Which would be the major product of the reaction shown? CH2CH3 1. Hg(OAc)2, THF, H2O ? 2. NaBH4, NaOH H OH OHCH2CH3 A) B) C) D) E) H H CH2CH3 H CH2CH3 H CH2CH3 H CH2CH2OH H H H OH H I II III IV V I II III IV V Ans: B Topic: Alcohol Reactions 46. A) B) C) D) E) O Which reagent(s) would transform propyl alcohol into propyl bromide? Concd. HBr and heat PBr3 NaBr/H2O and heat More than one of these All of these Ans: D 378 Chapter 11 Topic: Epoxide Reactions 47. Epoxidation followed by reaction with aqueous base converts cyclopentene into which of these? H OH I A) B) C) D) E) H H OH H OH OH OH H H OH II III IV OH H I II III IV Equal amounts of III and IV Ans: E Topic: Ether Synthesis 48. When 3-methyl-2-pentene is treated with mercuric acetate, Hg(O2CCH3)2, in a THFethanol mixture and the resulting product reacted with NaBH4 in basic solution, the principal product formed is which of these? A) 3-methyl-3-pentanol B) 3-ethoxy-3-methylpentane C) 3-methyl-2-pentanol D) 2-ethoxy-3-methylpentane E) 1-ethoxy-3-methylpentane Ans: B Topic: Alcohol Synthesis 49. Anti-Markovnikov hydration of the carbon-carbon double bond occurs when an alkene reacts with: A) BH3:THF; then H2O2/OHB) BH3:THF; then CH3COOH C) Hg(OAc)2, THF, H2O; then NaBH4, OHD) Hg(OAc)2, THF, CH3OH; then NaBH4, OHE) Hg(OAc)2, THF, H2O; then BH3:THF Ans: A 379 Chapter 11 Topic: Alcohol Reactions CH3 50. H3C A) B) C) D) E) CH CH3 CH CH3 to H3C CH CH CH3 OH Br is best The conversion of achieved through use of which of these reagents in a low temperature reaction? Concd. HBr Br2 NaBr, H2SO4 PBr3 HBr, peroxide Ans: D Topic: Alcohol Reactions 51. The conversion of 3-methyl-1-octanol to 1-chloro-3-methyloctane is best achieved through use of which of these reagents? A) Concd. HCl B) SO2Cl2 C) NaCl, H2SO4 D) PCl3 E) SOCl2 Ans: D Topic: Alcohol Reactions 52. What is the product of the reaction of propyl alcohol with (CH3)3SiCl in the presence of a tertiary amine? A) CH3CH2CH2Si(CH3)3 B) (CH3)2CHSi(CH3)3 C) CH3CH2CH2OSi(CH3)3 D) (CH3)2CHOSi(CH3)3 E) (CH3CH2CH2)3SiOH Ans: C 380 Chapter 11 Topic: Alcohol Synthesis 53. What is the major product of the reaction: i) BH3, THF ii) H2O2,NaOH CH3 CH3 ? CH3 OH + enantiomer I A) B) C) D) E) II CH3 OH OH III + enantiomer IV I II III IV Both III and IV Ans: D Topic: Alcohol Synthesis 54. What is the major product of the reaction when (R)-3-methylcyclohexene is subjected to the hydroboration-oxidation sequence? A) (1R,2R)-2-methylcyclohexanol + (1S,2R)-2-methylcyclohexanol B) (1S,2R)-2-methylcyclohexanol + (1S,2S)-2-methylcyclohexanol C) (1R,3R)-3-methylcyclohexanol + (1S,3R)-3-methylcyclohexanol D) (1S,3R)-3-methylcyclohexanol (1S,3S)-3-methylcyclohexanol E) Two of the above Ans: E 381 Chapter 11 Topic: Alcohol Synthesis 55. Oxymercuration-demercuration of 3-methylcyclopentene produces this/these product(s): HO CH3 CH2OH CH3 CH3 OH OH I A) B) C) D) E) II III IV I II III IV Both III and IV Ans: E 382 Chapter 11 Topic: Alcohol Reactions O 56. CH3 S OH, O Methanesulfonic acid, is treated, in turn, with PCl5 and (R)-2-butanol. Which of the following Fischer formulas is a stereochemically correct representation of the final product? CH3 O CH3 S O C H CH3 CH2 O H O S O C CH3 CH3 CH2 O CH3 S C O CH2 CH3 II O H S C O CH2 CH3 III CH3 O CH3 S C O CH2 CH3 CH3 IV A) B) C) D) E) CH3 CH3 I CH3 O V I II III IV V Ans: A 383 Cl H Chapter 11 Topic: Epoxide Reactions 57. cis-3-Hexene is treated with magnesium monoperoxyphthalate and the product is then subjected to acid-catalyzed hydrolysis. What is the final product? H H A) B) C) D) E) CH2CH3 H OH CH2CH3 CH2CH3 H H HO CH2CH3 H CH2CH3 CH2CH3 OH H HO H OH HO H CH2CH3 CH2CH3 H II I equal amounts I and II equal amounts I, II and V equal amounts III, IV and V equal amounts, III and IV Only V Ans: D III IV H H CH2CH3 OH OH CH2CH3 V Topic: Chemical Tests 58. Which of the following reagents might serve as the basis for a simple chemical test that would distinguish between pure 1-butene and CH3CH2CH2CH2OH? A) Bromine in carbon tetrachloride B) Dilute aqueous potassium permanganate C) Chromic oxide in aqueous sulfuric acid D) All of these E) None of these Ans: D Topic: Chemical Tests 59. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between and ? O A) B) C) D) E) AgNO3 in alcohol NaOH in H2O Br2 in CCl4 Cold concd. H2SO4 KMnO4 in H2O Ans: D 384 Chapter 11 Topic: Chemical Tests 60. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between ? and O A) B) C) D) E) Br AgNO3 in C2H5OH Dilute HCl Br2 in CCl4 NaOH in H2O KMnO4 in H2O Ans: A Topic: Physical Properties, Comparison 61. Which of the compounds listed below would you expect to have the highest boiling point? (They all have approximately the same molecular weight.) A) CH3CH2CH2CH2CH3 B) CH3CH2CH2CH2OH C) CH3CH2CH2OCH3 D) CH3CH2CH2Cl E) CH3CH2OCH2CH3 Ans: B Topic: Physical Properties, Comparison 62. A) B) C) D) E) Which compound would have the highest boiling point? CH3CH2CH2CH3 CH3CH2OCH3 CH3CH2CH2OH (CH3)2CHOH HOCH2CH2OH Ans: E Topic: Physical Properties, Comparison 63. A) B) C) D) E) Which compound would have the lowest solubility in water? Diethyl ether Methyl propyl ether 1-Butanol 2-Butanol Pentane Ans: E 385 Chapter 11 Topic: Physical Properties, Comparison 64. Which compound would have the lowest boiling point? O I A) B) C) D) E) CH2OH OH OH II III IV OH V I II III IV V Ans: A Topic: Physical Properties, Comparison 65. Which compound would have the highest boiling point? O O O O O OH I II III OH O O IV A) B) C) D) E) OH V I II III IV V Ans: E Topic: Alcohol Reaction Rates 66. A) B) C) D) E) Which of the alcohols listed below would you expect to react most rapidly with HBr? CH3CH2CH2CH2CH2CH2OH (CH3CH2)2CH2CH2OH (CH3CH2)2CHOHCH3 CH3CH2CH2CH2CH2OH (CH3CH2)2C(CH3)OH Ans: E 386 Chapter 11 Topic: Alcohol Reaction Rates 67. A) B) C) D) E) Which alcohol would undergo acid-catalyzed dehydration most rapidly? 3,3-dimethyl-1-butanol 2,2-dimethyl-1-butanol 3,3-dimethyl-2-butanol 2-methyl-2-butanol All would undergo dehydration equally rapidly. Ans: D Topic: Ether Reaction Rates 68. Which of these ethers is most resistant to peroxide formation on exposure to atmospheric oxygen? A) CH3OCH2CH3 B) CH3CH2OCH2CH3 C) (CH3)2CHOCH(CH3)2 D) (CH3)2CHOCH2CH3 E) CH3OC(CH3)3 Ans: E Topic: Ether Reaction Rates 69. Which of these ethers is least likely to undergo significant cleavage by hot aqueous H2SO4 ? A) B) C) D) E) CH3OCH3 CH3OCH(CH3)2 (CH3)2CHOCH(CH3)2 I II III (CH3)3COC(CH3)3 O IV V I II III IV V Ans: A 387 Chapter 11 Topic: Alcohol Reaction Rates 70. A) B) C) D) E) Which of these alkyl halide syntheses is predicted to occur at the greatest rate? CH3CH2CH2CH2OH + HI ⎯⎯⎯⎯→ (CH3)2CHCH2OH + HBr ⎯⎯⎯⎯→ CH3CHOHCH2CH3 + HCl ⎯⎯⎯⎯→ CH3CHOHCH2CH3 + HBr ⎯⎯⎯⎯→ (CH3)3COH + HI ⎯⎯⎯⎯→ Ans: E Topic: Reaction Mechanisms 71. The following reaction, HBr CH3CH2CH2CH2OH A) B) C) D) E) CH3CH2CH2CH2Br heat + H2 O is probably: An SN1-type reaction involving the protonated alcohol as the substrate. An SN2-type reaction involving the protonated alcohol as the substrate. An E1-type reaction involving the protonated alcohol as the substrate. An E2-type reaction involving the protonated alcohol as the substrate. An epoxidation reaction. Ans: B Topic: Reaction Mechanisms 72. The reaction between 1-pentanol and HBr to yield 1-bromopentanol is probably: A) B) C) D) E) an SN1-type reaction involving the protonated alcohol as the substrate. an SN2-type reaction involving the protonated alcohol as the substrate. an E1-type reaction involving the protonated alcohol as the substrate. an E2-type reaction involving the protonated alcohol as the substrate. an epoxidation reaction. Ans: B Topic: Reaction Mechanisms 73. The reaction between 2-methyl-2-pentanol and HBr to yield 2-bromo-2-methylpentane is probably: A) an SN1-type reaction involving the protonated alcohol as the substrate. B) an SN2-type reaction involving the protonated alcohol as the substrate. C) an E1-type reaction involving the protonated alcohol as the substrate. D) an E2-type reaction involving the protonated alcohol as the substrate. E) an epoxidation reaction. Ans: A 388 Chapter 11 Topic: Reaction Mechanisms 74. The reaction between 2-methyl-2-pentanol and HBr to yield 2-methyl-2-pentene is probably: A) an SN1-type reaction involving the protonated alcohol as the substrate. B) an SN2-type reaction involving the protonated alcohol as the substrate. C) an E1-type reaction involving the protonated alcohol as the substrate. D) an E2-type reaction involving the protonated alcohol as the substrate. E) an epoxidation reaction. Ans: C Topic: Reaction Mechanisms 75. The reaction between 4-methyl-1-pentanol and HBr to yield 4-methyl-1-pentene is probably: A) an SN1-type reaction involving the protonated alcohol as the substrate. B) an SN2-type reaction involving the protonated alcohol as the substrate. C) an E1-type reaction involving the protonated alcohol as the substrate. D) an E2-type reaction involving the protonated alcohol as the substrate. E) an epoxidation reaction. Ans: D Topic: Reaction Mechanisms 76. Which statement is true concerning the formation of alcohols by the hydroborationoxidation sequence? A) Overall, the process results in syn addition and anti-Markovnikov orientation. B) Overall, the process results in anti addition and anti-Markovnikov orientation. C) Overall, the process results in syn addition and Markovnikov orientation. D) Overall, the process results in anti addition and Markovnikov orientation. E) The stereochemistry and orientation are unpredictable. Ans: A 389 Chapter 11 Topic: Reaction Mechanisms 77. What is the electrophilic species involved in the initial step of the reaction below? Hg(OAc)2 OH HgOAc THF, H2O A) B) C) D) E) + OH HgOAc H3O+ THF the THF/H2O complex Ans: B + Topic: Reaction Mechanisms 78. The following reaction, 2 CH3CH2CH2CH2OH A) B) C) D) E) H2SO4 (CH3CH2CH2CH2)2O heat is probably: an SN1-type reaction involving the protonated alcohol as the substrate. an SN2-type reaction involving the protonated alcohol as the substrate. an E1-type reaction involving the protonated alcohol as the substrate. an E2-type reaction involving the protonated alcohol as the substrate. an epoxidation reaction. Ans: B Topic: Stereoisomerism 79. What is the relationship between alcohols I and II? H H CH3 OH H A) B) C) D) E) H CH3 OH I II They are: different conformations of the same compound. constitutional isomers. enantiomers. diastereomers. identical. Ans: D 390 + H2O Chapter 11 Topic: Stereoisomerism 80. What is the relationship between alcohols I and II? H CH3 CH3 OH H A) B) C) D) E) H H OH I II They are: different conformations of the same compound. constitutional isomers. enantiomers. diastereomers. identical. Ans: C Topic: Ether Reactivity 81. Which of the following statements is NOT true of ethers? A) Ethers are generally unreactive molecules toward reagents other than strong acids. B) Ethers generally have lower boiling points than alcohols of a corresponding molecular weight. C) Ethers generally have much lower water solubilities than alcohols with a corresponding molecular weight. D) Ethers can generally be cleaved by heating them with strong acids. E) Ethers form peroxides when allowed to stand in the presence of oxygen. Ans: C 391 Chapter 11 Topic: General 82. Which compound is a tosylate? O CH3 O S O CH3 Br O O S O CH2 CH3 CH3 S O CH3 O I II III O O CH3 S CH3 CH3 O S CH3 O IV A) B) C) D) E) V I II III IV V Ans: A Topic: General 83. A) B) C) D) E) The major industrial process in use today for the production of methanol is the: hydration of ethyne. distillation of wood. hydrogenation of carbon dioxide. reduction of methanal. catalytic reduction of carbon monoxide. Ans: E Topic: General 84. A) B) C) D) E) Today, most industrial ethanol is made in the U.S. by the: fermentation of grain. hydrolysis of ethyl bromide. hydration of ethylene. reduction of acetaldehyde. hydration of acetylene. Ans: C 392 Chapter 11 Topic: Ether Reactivity 85. Long-term storage of ethers can be dangerous, because most ethers react slowly with oxygen by a radical process called __________________. This process forms peroxides and hydroperoxides which are dangerously _______________. Ans: autooxidation, explosive Topic: General, Alcohol Synthesis 86. We have learned three different methods to convert alkenes into alcohols. a. The method that takes place with Markovnikov regioselectivity but is prone to rearrangement is ________________. b. The method that takes place with Markovnikov regioselectivity and does not lead to rearrangement is _____________. c. The method that takes place with anti-Markovnikov regioselectivity and syn stereoselectivity is _______________. Ans: a. acid-catalyzed hydration; b. oxymercuration-demercuration; c. hydroborationoxidation Topic: General, Alcohol Reactions 87. Reactions of alcohols can be broadly categorized into three types. a. Those that utilize the hydroxyl oxygen as a ____________. b. Those that utilize the hydroxyl proton as an _________. c. Those that convert the hydroxyl group into a _____________. Ans: a nucleophile or base; b. acid; c. leaving group Topic: General 88. Stereochemically speaking, conversion of an alcohol into a tosylate occurs with _____________ of configuration. Ans: retention Topic: General 89. When an alcohol in which the OH is attached to a stereogenic carbon reacts with thionyl chloride (SOCl2) in the presence of a 3° amine, the resulting alkyl chloride is produced with _____________ of configuration. Ans: inversion Topic: General 90. The SN2 reaction between an alkoxide and an alkyl halide is commonly referred to as the _________________ synthesis. Ans: Williamson 393 Chapter 11 Topic: General 91. Three-membered rings containing oxygen are called _______________ or ______________. Ans: oxiranes; epoxides Topic: General 92. The development of a procedure called __________________ has made the use of nonpolar solvents possible in reactions involving polar reagents. Ans: phase transfer catalysis Topic: General 93. The relationship between a crown ether and the ion it transports is known as the ____________________ relationship. Ans: host-guest Topic: General 94. A compound or ion that prefers a nonpolar environment to an aqueous one is said to be ______________. Ans: lipophilic Topic: Isomerism 95. Draw structures for all possible ethers having the formula C4H10O O Ans: O O C4H10O: ethers Topic: Ether Synthesis 96. Which is the most efficient way to prepare isopropyl methyl ether via the Williamson method? Ans: CH3I + (CH3)2CHONa Topic: Ether Synthesis 97. Which is the best method to prepare ethoxycyclopentane via the Williamson method? Ans: O ONa + I 394 Chapter 11 Topic: Alcohol Synthesis 98. Draw the structures of all the products formed when (3R)-3-methylcyclopentene is subjected to the hydroboration-oxidation sequence. Ans: The alkene is symmetrically substituted: thus, Markovnikov rule does not apply. Hence, all four products shown below are likely to be formed in roughly equal proportions. H3C H hydroboration-oxidation (3R)-3-methylcyclopentene H3C H3C H H3C H H3C H H OH OH + + + OH OH Topic: Ether Synthesis 99. Provide a reasonable synthetic strategy for the synthesis of trans-1,2-cyclohexanediol from bromocyclohexane OH Ans: Br CH ONa MMPP H3O+ 3 O CH3OH OH heat + enantiomer Topic: Nomenclature 100. Give the correct IUPAC name corresponding to the following structure: OH Ans: 6-cyclohexyl-2,7-dimethyl-3-octanol 395 Chapter 11 Topic: Nomenclature 101. Give the correct IUPAC name corresponding to the following structure: OH Ans: (R)-3-ethyl-2-methyl-3-hexanol Topic: Nomenclature 102. Give the correct IUPAC name corresponding to the following structure: O O Ans: 1,3-diethoxyhexane Topic: Nomenclature 103. Give the correct IUPAC name corresponding to the following structure: Br H CH3 OH Ans: (1R,2R)-2-bromo-1-methylcyclopentanol Topic: Multistep Synthetic Strategy 104. Provide a reasonable synthetic strategy for the synthesis of a racemic mixture of (1R,2R) and (1S,2S)-2-bromo-1-methylcyclopentanol from methylcyclohexane. CH3 Ans: CH3 Br CH3 2 CH3ONa Br CH3OH hν heat Br2, H2O Br H Br CH3 OH + H CH3 OH (1R,2R) (1S,2S) 2-bromo-1-methylcyclopentanol 396 Chapter 11 Topic: Multistep Reactions 105. Complete the following reaction sequence, giving structural details of all key intermediates: i) Li, NH3 ? ii) KMnO4 ,OH−, H2O Ans: iii) H3O+ Li NH3 i) KMnO4 ,OH−, H2O ii) H3O+ H H OH OH + HO H HO 2S,3R H 2R,3S Topic: Multistep Reactions 106. Complete the following reaction sequence, giving structural details of all key intermediates: i) H2, Lindlar catalyst ? ii) KMnO4 ,OH−, H2O iii) H3O+ Ans: H2 Lindlar catalyst − H OH i) KMnO4 ,OH , H2O ii) H3O+ HO H meso 397 Chapter 11 Topic: Multistep Reactions 107. Complete the following reaction sequence, giving structural details of all key intermediates: i) Li, NH3 ? ii) MMPP Ans: iii) H3O+, H2O Li NH3 i) MMPP ii) H3O+, H2O H H OH OH + H OH H 2S, 3S OH 2R, 3R 398 Chapter 12 MULTIPLE CHOICE QUESTIONS Topic: General Carbonyl Information 1. Which of the following resonance structures is not a significant contributor to the hybrid for the carbonyl group? C O I A) B) C) D) E) C O C II O III I II III Neither II nor III is important. All are significant contributors. Ans: B Topic: General Carbonyl Information 2. When nucleophilic addition to a carbonyl group occurs, the carbon attacked undergoes this hybridization change: A) sp2 ⎯⎯⎯⎯→ sp3 B) sp ⎯⎯⎯⎯→ sp2 C) sp ⎯⎯⎯⎯→ sp3 D) sp3 ⎯⎯⎯⎯→ sp2 E) sp2 ⎯⎯⎯⎯→ sp Ans: A Topic: Functional Group Tests 3. A) B) C) D) E) Which reagent(s) will distinguish between cyclopentanol and cyclopentane? Br2/CCl4 KMnO4 (cold) CrO3/aqueous H2SO4 NaOH (aq) A) and B) Ans: C Page 399 Chapter 12 Topic: Functional Group Tests 4. Which reagent(s) will distinguish between 2-methylcyclopentanol and 1methylcyclopentanol? A) Br2/CCl4 B) KMnO4 C) CrO3/aqueous H2SO4 D) NaOH (aq) E) B) and C) Ans: E Topic: Functional Group Tests 5. Which of the following reagents might serve as the basis for a simple chemical test that would distinguish between CH3CH=CHCH3 and CH3CHOHCH2CH3? A) CrO3 in H2SO4 B) KMnO4 C) Br2 in CCl4 D) Two of these E) All of these Ans: D Topic: Functional Group Tests 6. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between CH3CH=CHCH2OH and CH3CH2CH2CH2OH ? A) CrO3 in H2SO4 B) Cold conc. H2SO4 C) Br2 in CCl4 D) NaOH/H2O E) NaBH4 Ans: C Topic: Functional Group Tests 7. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between (CH3)2C=CHCH2CH2OH and (CH3)2CHCH2CH2CH2OH ? A) CrO3 in H2SO4 B) Cold conc. H2SO4 C) Br2 in CCl4 D) NaOH/H2O E) NaBH4 Ans: C 400 Chapter 12 Topic: Functional Group Tests 8. Which of the reagents/techniques listed below would serve as the basis for a simple chemical test to distinguish between 2-methyl-3-hexyn-1-ol and 2-methyl-5-hexyn-1-ol? A) CrO3 in H2SO4 B) Cold conc. H2SO4 C) Br2 in CCl4 D) NaBH4 E) IR spectroscopy Ans: E Topic: Functional Group Tests 9. Which of the reagents/techniques listed below would serve as the basis for a simple chemical test to distinguish between 2-methyl-3-hexyn-2-ol and 2-methyl-5-hexyn-1-ol? A) CrO3 in H2SO4 B) IR spectroscopy C) Br2 in CCl4 D) A) and B) E) All of the above Ans: D Topic: Functional Group Tests 10. Which of the reagents/techniques listed below would serve as the basis for a simple chemical test to distinguish between CH3CH2CH=CHCH2CH2CHO and CH3CH2CH=CHCH2CH2CH2OH? A) KMnO4 B) IR spectroscopy C) Br2 in CCl4 D) A) and B) E) All of the above Ans: B Topic: Functional Group Tests 11. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between (CH3)3COH and (CH3)2CHCH2OH ? A) NaH B) NaOH/H2O C) Br2 in CCl4 D) Cold conc. H2SO4 E) CrO3 in H2SO4 Ans: E 401 Chapter 12 Topic: Functional Group Tests 12. CrO3 in H2SO4/H2O will fail to give a positive test with which of these compounds? A) CH3CH2CH2CH2OH B) CH3CHCH2CH3 OH C) (CH3)3COH H D) CH3CH2CH2C O E) More than one of these Ans: C Topic: Functional Group Tests 13. A) B) C) D) E) CH3 Consider the molecule CH3CHC CHCH2OH. Which reagent will not give a positive test with this compound? Cold conc. H2SO4 Br2/CCl4 NaOH (aq) CrO3/H2SO4 Dilute KMnO4/H2O Ans: C 402 Chapter 12 Topic: Reactions and Reaction Sequences 14. The final product, D, in the following reaction sequence, CH2 CH2 CH3CHOH PBr3 CH3 A Mg ether A) CH3CHOCH2CH2OH B) C) CH3 CH3CHCH2CH2OH D) CH3 CH3CHOCH2CH3 E) CH3 CH3CHCH2CH3 C H3O+ D , would be? CH3 CH3CHCH2CH2Br B O CH3 Ans: C 403 Chapter 12 Topic: Reactions and Reaction Sequences 15. What is the product, A, that would be obtained from the following reaction sequence? O C CH CH3CH2MgBr CH3 C CCH2CH3 C CCH I CH3CH C CCH A CH3 CHOCH2CH3 CH3 CH3CH2 II CH3 C CCH III CH3 CH3 CHOH C C IV A) B) C) D) E) H3O+ CHCH3 O V I II III IV V Ans: D 404 CHCH2CH3 CH3 CHOH Chapter 12 Topic: Reactions and Reaction Sequences 16. What is the product, A, that would be obtained from the following reaction sequence? CH2 CH2 CH3CH2MgBr C CH C CCH2CH3 C CCH2CH2OCH2CH3 I H3O+ O A CH3CH2 II C CCH2CH2OH III CH3 C CCH2CH2OCH3 C COCHCH2CH3 IV A) B) C) D) E) V I II III IV V Ans: C Topic: Reactions and Reaction Sequences 17. What would be the product, C, of the following reaction sequence? CH3 CH3 Li CH3CCH2Br ether CuI A B CH3 A) B) C) D) E) 2,6-Dimethylheptane 2,2-Dimethylpropane 2-Methylpentane 2,2,5-Trimethylhexane 2,2,6-Trimethylheptane Ans: E 405 CH3CHCH2CH2Br C Chapter 12 Topic: Reactions and Reaction Sequences 18. What would be the product, O, of the following reaction sequence? CH3CH2CHCH3 Mg ether Br D2O N O A) CH3CH2CH2CH3 B) CH3CH2CHCH3 C) D CH3CH2CHCH3 OD D) CH3CH2CH2CH2OD E) CH3CH2CH2CH2D Ans: B Topic: Reactions and Reaction Sequences 19. What is the product, A, that would be obtained from the following reaction sequence? OH PBr3 Li NH4Cl (CH3)2C=O 10oC A OH OH I II III HO IV A) B) C) D) E) V I II III IV V Ans: D 406 Chapter 12 Topic: Reactions and Reaction Sequences 20. What is the product, A, that would be obtained from the following reaction sequence? OH PBr3 H3O+ heat (CH3)2C=O Mg, Et2O A OH OH I II III HO IV A) B) C) D) E) V I II III IV V Ans: C Topic: Reactions and Reaction Sequences 21. What would be the final product, A, in the following reaction sequence? O OH PBr3 Mg, Et2O OH O I II Br III O IV V I II III IV V Ans: C 407 A OH OH A) B) C) D) E) H3O+ heat Chapter 12 Topic: Reactions and Reaction Sequences 22. What is the final product of the following reaction sequence? O i) Mg, Et2O CH3I H2CrO4 acetone + ii) H3O A O OH II III O O I OH O IV A) B) C) D) E) V I II III IV V Ans: E 408 Chapter 12 Topic: Reactions and Reaction Sequences 23. What would be the alkane C that is the product of the following reaction sequence? CH3 CH3CHBr A) CH3 CH3 Li ether CuI A B CH3CHCHCH2CH3 B) CH3 CH3CH CHCH2CH3 CH3 C) CH3 CH3 CH3CHCH2CHCH3 CH3 CH3 D) CH3CH CH3 CCH3 CH3 CH3 E) CH3CH2CH2CH2CHCH3 Ans: C 409 CH3CHCH2Br C Chapter 12 Topic: Reactions and Reaction Sequences 24. What would be the major product of the following reaction? O O i) NaBH4 ii) ethylene oxide, HA OH I HO HO O O O III II O A O OH OH IV A) B) C) D) E) V I II III IV V Ans: A Topic: Reactions and Reaction Sequences 25. What would be the major product of the following reaction? O i) NaBH4 ii) NaH, Et2O iii) O S A O OCH2CH3 A) B) C) D) E) CH3CH2OCH(CH3)CH2CH2CH2CH3 (CH3CH2O)2CHCHOHCH2CH2CH3 (CH3CH2)2CHOHCH2CH2CHOHCH3 CH3OCH(C2H5)CH2CH2CH2CH3 CH3CH2CH(OCH3)CH2CH2CHOHCH3 Ans: A 410 OH Chapter 12 Topic: Reactions and Reaction Sequences 26. What would be the major product of the following reaction? Cl A) B) C) D) E) Li, Et2O CuI H Br CH3 A (R)-3-ethyl-5-methylheptane (R,S)-3-ethyl-5-methylheptane (S)-3-ethyl-5-methylheptane (3R,5S)-5-ethyl-3-methylheptane (3S,5R)-5-ethyl-3-methylheptane Ans: C Topic: Reactions and Reaction Sequences 27. What is the principal product(s) formed when 1 mol of methylmagnesium iodide reacts with 1 mol of p-hydroxyacetophenone ? O CH3MgI A HO O O OMgI + CH4 IMgO HO O II I III O O O MgI IMgO IV A) B) C) D) E) V I II III IV V Ans: A 411 Chapter 12 Topic: Reactions and Reaction Sequences 28. What is (are) the principal product(s) formed when 1 mol of ethylmagnesium bromide reacts with 1 mol of 3-(N-methylamino)cyclopentanone ? H N O H3C CH3 BrMgN O + CH4 CH3CH2MgBr H N H N CH2CH3 OMgBr H3C H N CH2CH3 N OMgBr O H3C IV V I II III IV V Ans: A Topic: Reactions and Reaction Sequences 29. What would be the product, A, of the following reaction ? i) NaBD4 A ii) H2O O A) OD B) D OH C) D OD D) OH E) D O Ans: B 412 CH2CH3 III H3CH2C H3C O H3C II I A) B) C) D) E) A Chapter 12 Topic: Reactions and Reaction Sequences 30. What is the predominant product from the reaction of 2-hexanol with H2CrO4? A) CH3CO2H B) CH3(CH2)3CO2H O C) CH3(CH2)3CCH3 D) CH3(CH2)4CO2H E) A) and B) Ans: C Topic: Synthetic Strategy, Redox 31. Which of the reagents listed below would efficiently accomplish the transformation of CH3CH2CH=CHCH2CH2CHO into CH3CH2CH=CHCH2CH2CH2OH? A) KMnO4 B) NaBH4 C) Br2 in CCl4 D) H2, Ni E) Two of the above Ans: B Topic: Synthetic Strategy, Redox 32. Which of the reagents listed below would efficiently accomplish the transformation of CH3CH2CH=CHCH2CH2CHO into CH3CH2CH2CH2CH2CH2CH2OH? A) KMnO4 B) NaBH4 C) Br2 in CCl4 D) H2, Ni E) Two of the above Ans: D Topic: Synthetic Strategy, Redox 33. Which of the reagents listed below would efficiently accomplish the transformation of CH3CH2C≡CCH2CH2CHO into CH3CH2C≡CCH2CH2CH2OH? A) KMnO4 B) NaBH4 C) Br2 in CCl4 D) H2, Ni E) Two of the above Ans: B 413 Chapter 12 Topic: Synthetic Strategy, Redox 34. Which of the reagents listed below would efficiently accomplish the transformation of CH3CH2CH=CHCH2CH2CH2OH into CH3CH2CH=CHCH2CH2CHO ? A) KMnO4(aq, alkaline) B) CrO3 / H2SO4 C) PCC in CH2Cl2 D) Br2, CCl4 E) Two of the above Ans: C Topic: Synthetic Strategy 35. Which of the reagents listed below would efficiently accomplish the transformation of 2-methyl-3-cyclopentenol into 2-methyl-3-cyclopentenone? OH O ? A) B) C) D) E) KMnO4(aq, alkaline) CrO3/H2SO4 H2, Pt Br2, CCl4 Two of the above Ans: B Topic: Synthetic Strategy, Redox 36. Which of the reagents listed below would efficiently accomplish the transformation of 3-methyl-3-cyclopentenone into 3-methyl-3-cyclopentenol? OH O ? A) B) C) D) E) i) LiAlH4; ii) H2O NaBH4,H2O H2, Pd A) and B) A), B) and C) of the above Ans: D 414 Chapter 12 Topic: Synthetic Strategy, Redox 37. Which of the reagents listed below would efficiently accomplish the transformation of ethyl-3-pentenoate into 3-penten-1-ol? HO O ? O A) B) C) D) E) i) LiAlH4; ii) H2O NaBH4,H2O H2, Pd A) and B) A), B) and C) of the above Ans: A Topic: Reactions and Reaction Sequences 38. A) B) C) D) E) When 2-pentanol is treated with chromic acid, The color changes from orange to blue The color changes from purple to colorless The color changes from blue to red The color changes from orange to green The color changes from green to orange Ans: D Topic: Reactions and Reaction Sequences 39. A) B) C) D) E) When 1-pentanol is treated with alkaline potassium permanganate, The color changes from orange to blue The color changes from purple to colorless The color changes from blue to red The color changes from orange to green The color changes from green to orange Ans: B Topic: Reactions and Reaction Sequences 40. A) B) C) D) E) When 3-methyl-3-pentanol is treated with chromic acid, The color changes from orange to blue The color changes from purple to colorless The purple color remains unchanged The color changes from orange to green The orange color remains unchanged Ans: E 415 Chapter 12 Topic: Reactions and Reaction Sequences 41. What is the final product? O CH3C A) CH3CCH3 CH3I liq. NH3 HO CH3CC B) NaNH2 CH CCH3 CH3 OCH3 CH3CC CCH3 CH3 OCH3 C) D) CH3C COCH2CHCH3 CH3 CH3CC CONa CH3 E) None of these Ans: B Topic: Reactions and Reaction Sequences 42. What product(s) is/are formed in the following reaction? O D2O LiAlD4 ? ether CH3CH2CH2COCH2CH3 A) CH3CH2CH2CH2OD + CH3CH2OD B) CH3CH2CH2CD2OD + CH3CH2OD C) CH3CH2CH2CD2OH + CH3CH2OH D) CH3CH2CH2CHDOD + CH3CH2OD OD E) CH3CH2CH2CDOCH2CH3 Ans: B 416 ? Chapter 12 Topic: Reactions and Reaction Sequences 43. What product(s) is/are produced in the 1:1 reaction of sec-butylmagnesium bromide with OH H ? CH3CHCH2CH2C OH A) O OMgBr CH3CHCH2CH2CHCCH2CH3 CH3 B) OMgBr H + CH3CH2CH2CH3 C) CH3CHCH2CH2C O OH OMgBr D) CH3CHCH2CH2CHCH2CH(CH3)2 H OMgBr O E) CH3CHCH2CH2C H CH3CHCH2CH2C O + (CH3)3CH OCHCH2CH3 CH3 Ans: B 417 Chapter 12 Topic: Reactions and Reaction Sequences 44. What is the principal product of the following reaction: O + CH3CH2CH2CH2MgBr/ether; then H2O ⎯⎯⎯⎯→ ? A) CH3CHCH2CH2CH2CH3 CH3CH B) CH2 CH2OH OH C) CH3CHCH2CH2CH2CH2CH3 OH D) CH3CHCH2OCH2CH2CH2CH3 CH3CHOCH2CH2CH2CH3 E) CH2OH CH3CHCH2OCH2CH2CH2CH3 OCH2CH2CH2CH3 Ans: B Topic: Reactions and Reaction Sequences 45. A) B) C) D) E) The reaction of lithium di-sec-butylcuprate with isopentyl bromide yields: 2,5-Dimethylheptane 2,6-Dimethylheptane 3,5-Dimethylheptane 3,4-Dimethylheptane 3,6-Dimethylheptane Ans: A Topic: Reactions and Reaction Sequences 46. A) B) C) D) E) The reaction of lithium diethylcuprate with 1-bromo-4,4-dimethylhexane yields: 3,3-Dimethylheptane 3,3-Dimethyloctane 1-Ethyl-4,4-dimethylhexane Di-4,4-dimethylhexylcuprate None of the above Ans: B 418 Chapter 12 Topic: Reactions and Reaction Sequences 47. What compound(s) result(s) from the reaction of CH3CH2CH2MgBr with CH3CH2CH2CH2CO2H (1:1 mole ratio)? A) (CH3CH2CH2)2CCH2CH2CH2CH3 OH O B) C) CH3CH2CH2CCH2CH2CH2CH3 O CH3CH2CH2CH2COCH2CH2CH3 D) CH3CH2CH3 + CH3CH2CH2CH2CO2MgBr O O E) CH3CH2COCCH2CH2CH2CH3 Ans: D Topic: Synthetic Strategy C6H5 48. CH3CH2CH2CCH3 OH Your task is to synthesize through a Grignard synthesis. Which pairs of compounds listed below would you choose as starting materials? O A) CH3CH2CH2Br and B) C) CH3CC6H5 O CH3CH2CH2CH and C6H5Br O CH3CH2CHCH3 and C6H5CH Br D) More than one of these E) None of these Ans: A 419 Chapter 12 Topic: Synthetic Strategy 49. Which of the following synthetic procedures would be employed most effectively to transform ethanol into ethyl propyl ether? A) Ethanol + HBr, then Mg/ether, then H3O+, then NaH, then CH3CH2Br B) Ethanol + HBr, then Mg/ether, then HCHO, then H3O+, then NaH, then CH3CH2Br C) Ethanol + CH3CH2CH2OH + H2SO4/140°C D) Ethanol + NaH, then HCHO, then H3O+, then HBr, then Mg/ether, then CH3CH2CH2Br E) Ethanol + H2SO4/180°C, then CH3CH2CH2Br Ans: B Topic: Synthetic Strategy 50. Your task is to synthesize 2-phenyl-2-hexanol through a Grignard synthesis. Which pair(s) of compounds listed below would you choose as starting materials? O A) CH3CH2CH2Br and B) CH3CHCH2Br CH3CC6H5 O and CH3CC6H5 CH3 O C) CH3CH2CH2CH2CCH3 and C6H5Br D) Answers A) or B) E) Answers A) or C) Ans: E Topic: Synthetic Strategy 51. How could the following synthesis be accomplished? O OH CH2CH A) O (1) SOCl2, (2) Mg, ether, (3) CH3CH, then H3O+ B) (1) SOCl2, (2) Li, ether, (3) (CH3CH2)2CuLi, (4) KMnO4, OHO C) 1) PBr3, (2) Mg, ether, (3) CH2 D) More than one of the above E) None of the above Ans: C CH2, then 420 H3O+ (4) PCC,CH2Cl2 Chapter 12 Topic: Synthetic Strategy, Redox 52. Select the correct reagent(s) for the following reaction: O OH CH3CCH2CH2CO2CH3 A) B) C) D) E) CH3CHCH2CH2CH2OH + LiAlH4/ether; then H3O NaBH4; then H3O+ H2 with Pt/C A) and B) A), B) and C) Ans: A Topic: Synthetic Strategy, Redox 53. Select the correct reagent(s) for the following reaction: O OH CH3CCH2CH2CO2CH3 A) B) C) D) E) CH3CHCH2CH2CO2CH3 + LiAlH4/ether; then H3O NaBH4; then H3O+ H2 with Pt/C B) and C) A), B) and C) Ans: D Topic: Synthetic Strategy, Redox 54. A) B) C) D) E) Which reagent(s) would you use to convert CH3(CH2)6CO2H to CH3(CH2)6CH2OH? NaBH4/H2O LiAlH4/ether, then H3O+ PCC/CH2Cl2 Zn, H3O+ H2, Pt Ans: B 421 Chapter 12 Topic: Synthetic Strategy OH 55. Which method would give (CH3)2CC CH ? A) CH3CHCH3 H2CrO4 NH4+ HC CNa acetic acid CH3CH2Li OH B) CH3CCH3 C) O CH3CC H3O+ H2CrO4 acetone CH 2 CH3MgBr NH4+ O D) More than one of the above E) None of the above Ans: D Topic: Synthetic Strategy 56. Which synthesis of a Grignard reagent would fail to occur as written? Mg, ether A) CH3OCH2CH2Br CH3OCH2CH2MgBr Mg, ether B) CH3CH2CH2I CH3CH2CH2MgI Mg, ether C) HO2CCH2CH2I HO2CCH2CH2MgI Mg, ether D) C6H5Br C6H5MgBr E) All of the above will succeed. Ans: C Topic: Synthetic Strategy 57. Which combination of reagents is to be preferred for the synthesis of 2,4dimethylhexane by the Corey-Posner, Whitesides-House procedure? A) Lithium diisobutylcuprate + sec-butyl bromide B) Lithium dimethylcuprate + 2-bromo-4-methylhexane C) Lithium dimethylcuprate + 4-bromo-2-methylhexane D) Lithium diisopropylcuprate + 1-bromo-2-methylbutane E) Lithium di(2-methylbutyl)cuprate + isopropyl bromide Ans: D 422 Chapter 12 Topic: Synthetic Strategy 58. Which of these reactions will not produce a 1° alcohol? 1. LiAlH4, Et2O A) (CH3)2CHCH2CH2MgBr 2. H3O+ CH2 1. CH2 B) (CH3)2CHCH2CH2MgBr C) O C6H5CCH3 D) E) O O+ 2. H3 1. NaBH4 2. H3O+ CH3CH2CH2CH2Li CH3(CH2)5COOH 1. H2C=O 2. H3O+ 1. LiAlH4, Et2O 2. H3O+ Ans: C 423 Chapter 12 Topic: Synthetic Strategy, Stereochemistry 59. Which of the following would serve as a synthesis of racemic 2-methyl-1-phenyl-2butanol? CH3 CCH2CH3 ? OH I CH3CH2CCH3 + CH2MgCl O O II + CH2CCH3 III CH2CCH2CH3 CH3CH2MgBr + CH3MgI O A) B) C) D) E) I II III All of the above None of the above Ans: D 424 1. Et2O 2. NH4+ 1. Et2O 2. NH4+ 1. Et2O 2. NH4+ Chapter 12 Topic: Synthetic Strategy, Stereochemistry 60. Which of the following reactions would serve as a reasonable synthesis of the following racemic alcohol (2-phenyl-2-butanol)? OH CH3CC6H5 C2H5 O A) B) CH3CC6H5 O C) C2H5CC6H5 O + C2H5MgBr + CH3MgBr + C6H5MgBr 1. Et2O 2. NH4+ 1. Et2O 2. NH4+ 1. Et2O 2. NH4+ CH3CC2H5 D) Answers A) and B) only E) Answers A), B) and C) Ans: E Topic: Synthetic Strategy, Stereochemistry 61. Which Grignard synthesis will produce an optically active product or product mixture? A) MgBr B) O + O ClMg + O C) + O D) E) MgI H CH3 O + H3C MgI H + MgBr O Ans: E 425 Chapter 12 Topic: Synthetic Strategy, Stereochemistry 62. Which reaction leads to an optically active product? A) + NaBH 4 O O B) ClMg + C) H CO2H H2, Pt + D) E) + H OH H3C CHO + O O KMnO4 LiAlH4 / Et2O (excess) Ans: C Topic: Acid/Base 63. A) B) C) D) Which of the following is the strongest acid? RMgX Mg(OH)X RH H2O Ans: D Topic: Acid/Base 64. A) B) C) D) Which of the following is the strongest base? RMgX Mg(OH)X RH H2O Ans: A Topic: Acid/Base 65. In which of the following series are the compounds arranged in order of decreasing basicity? A) CH3CH2MgBr > NaNH2 > HC≡CNa > NaOH > CH3CH2ONa B) CH3CH2MgBr > NaNH2 > HC≡CNa > CH3CH2ONa > NaOH C) HC≡CNa > CH3CH2MgBr > NaNH2 > CH3CH2ONa > NaOH D) NaNH2 > CH3CH2MgBr > HC≡CNa > CH3CH2ONa > NaOH E) None of these Ans: B 426 Chapter 12 Topic: Redox 66. A) B) C) D) E) Which reaction is an oxidation? RCHO ⎯⎯⎯⎯→ RCO2H RCH2OH ⎯⎯⎯⎯→ RCHO RCH2OH ⎯⎯⎯⎯→ RCO2H Two of these All of these Ans: E Topic: Synthetic Strategy, Redox 67. Which of these compounds will not be reduced by LiAlH4? A) CH3CH2CH2CH=CH2 H B) C) CH3CH2CH2C O O D) CH3CH2CH2COH O E) CH3CH2CH2COCH3 O CH3CH2CH2CCH3 Ans: A Topic: Synthetic Strategy, Redox 68. Which reagent(s) is/are capable of reducing the following ester to a primary alcohol ? O O A) B) C) D) E) LiAlH4 / ether NaBH4 / H2O Na / C2H5OH H2 / Ni, atmospheric pressure All can be used successfully. Ans: A 427 Chapter 12 Topic: Synthetic Strategy, Redox 69. Which reagent(s) is/are capable of reducing the following ester to an aldehyde ? O O A) B) C) D) E) LiAlH4 / ether NaBH4 / H2O Na / C2H5OH H2 / Ni, atmospheric pressure None of the above can be used successfully. Ans: E Topic: Redox 70. A) B) C) D) Which of these transformations cannot be classified as a reduction? RCH2Cl ⎯⎯⎯⎯→ RCH3 RCH=CH2 ⎯⎯⎯⎯→ RCH2CH3 RCOOH ⎯⎯⎯⎯→ RCH2OH O RCH2OH + R'OH E) All of these are reductions. Ans: E RCOR' Topic: Synthetic Strategy, Redox 71. Which of these compounds cannot be reduced by sodium borohydride? H A) B) (CH3)2CHC O C) CH3CH2CCH3 O O C6H5COH D) O CH3(CH2)4COCH3 E) Neither C) nor D) can be reduced. Ans: E 428 Chapter 12 Topic: Redox, Reaction Mechanisms 72. A) B) C) D) E) In the reaction of carbonyl compounds with LiAlH4, the effective reducing species is: Li+ Al+3 AlH4AlH3 HAns: E Topic: Redox, Reaction Mechanisms 73. The success in converting low molecular weight 1° alcohols to aldehydes by use of K2Cr2O7/H2SO4 as oxidant can be attributed to the fact that: A) dichromate is a relatively weak oxidizing agent. B) the presence of H2SO4 limits the oxidation. C) the aldehyde can be separated, as formed, by distillation. D) aldehydes are not oxidized by the K2Cr2O7/H2SO4 mixture. E) hydrogen bonding occurs between the alcohol and the acid present. Ans: C Topic: Redox, Reaction Mechanisms 74. A) B) C) D) E) Fundamentally, 2-methyl-2-pentanol does not undergo oxidation by H2CrO4 because: the intermediate chromate ester is not formed. the oxidant isn't in a sufficiently high oxidation state. the alcohol undergoes dehydration. the intermediate chromate ester cannot lose hydrogen. Actually, this oxidation does occur. Ans: D 429 Chapter 12 Topic: Synthetic Strategy, Redox 75. Which of these reduction reactions is unsuccessful? O A) B) CH3CH2CH2COCH2CH2CH3 H O C6H5CH2C + NaBH4, CH3OH O C) D) + LiAlH4, ether CH3(CH2)10COH O + H2, Pt, high pressure + NaBH4, CH3CH2OH E) All of these are successful reductions. Ans: C C6H5CCH2CH2CH2CH3 Topic: Synthesis of Grignards and Other Organometallics 76. Grignard reagents react with oxirane (ethylene oxide) to form 1° alcohols but can be prepared in tetrahydrofuran solvent. Why is this difference in behavior observed? A) Steric hindrance in the case of tetrahydrofuran precludes reaction with the Grignard. B) There is a better leaving group in the oxirane molecule. C) The oxirane ring is the more highly strained. D) It is easier to obtain tetrahydrofuran in anhydrous condition. E) Oxirane is a cyclic ether, while tetrahydrofuran is a hydrocarbon. Ans: C Topic: Synthesis of Grignards and Other Organometallics 77. Which of these compounds cannot be used to prepare the corresponding Grignard reagent? A) CH3OCH2CH2CH2Br B) (CH3)3CCl C) CH2=CHCH2Br D) (CH3)2NCH2CH2Br H E) O CCH2CH2I Ans: E 430 Chapter 12 Topic: Synthesis of Grignards and Other Organometallics 78. A) B) C) D) E) Which of these compounds can be used to prepare the corresponding Grignard reagent? CH3CHOHCH2CH2CH2CH2Br (CH3)3CHCHBrCH2CH2CO2H BrCH=CHCH2CH2CH3 CH3NHCH2CH2Br None of the above can be used to prepare the corresponding Grignard reagent Ans: C Topic: Reactivity of Grignards and Other Organometallics 79. A) B) C) D) E) Which of these is the least reactive type of organometallic compound? RK R2Hg RLi R2Zn R3Al Ans: B Topic: Synthesis of Grignards and Other Organometallics 80. If the role of the solvent is to assist in the preparation and stabilization of the Grignard reagent by coordination with the magnesium, which of these solvents should be least effective? CH3CH2OCH2CH3 I A) B) C) D) E) (CH3CH2)3N O II III CH3(CH2)4CH3 CH3OCH2CH2OCH3 IV V I II III IV V Ans: D 431 Chapter 12 Topic: Synthesis of Grignards and Other Organometallics 81. Which of these is most likely to be a successful synthesis of an organometallic compound? A) CH3CH2CH2MgBr + LiCl ⎯⎯⎯⎯→ CH3CH2CH2Li + MgBrCl B) 2 CH3CH2CH2CH2Li + ZnCl2 ⎯⎯⎯⎯→ (CH3CH2CH2CH2)2Zn + 2 LiCl C) 3 (CH3CH2)2Hg + 2 AlCl3 ⎯⎯⎯⎯→ 2 (CH3CH2)3Al + 3 HgCl2 D) (CH3CH2)3Al + 3 NaCl ⎯⎯⎯⎯→ 3 CH3CH2Na + AlCl3 E) (CH3)2Cu + MgBr2 ⎯⎯⎯⎯→ (CH3)2Mg + CuBr2 Ans: B SHORT ANSWER QUESTIONS Topic: General 82. Because the carbonyl carbon bears a partial positive charge, it is susceptible to ________________ attack. Ans: nucleophilic Topic: General, Redox 83. A reaction which increases the hydrogen content or decreases the oxygen content of an organic molecule is called a(n) _____________. Ans: reduction Topic: General, Redox 84. A reaction which increases the oxygen content or decreases the hydrogen content of an organic molecule is called a(n) _____________. Ans: oxidation Topic: General, Redox 85. LAH is the abbreviation for the powerful reducing agent ______________. Ans: lithium aluminum hydride Topic: General, Redox 86. A negatively charged hydrogen atom is called a ______________. Ans: hydride ion Topic: General, Redox Reagents 87. A solution of CrO3 in aqueous acetone is called the _______________. Ans: Jones reagent 432 Chapter 12 Topic: Functional Group Tests 88. Primary and secondary alcohols can be distinguished from most other compounds (with the exception of aldehydes) because they will react rapidly with a solution of CrO3 in aqueous sulfuric acid, causing a color change from ______________ to _____________. Ans: orange; green Topic: General 89. Compounds that contain carbon-metal bonds are known as _________________. Ans: organometallic compounds Topic: General 90. Organomagnesium halides are known as _______________. Ans: Grignard reagents Topic: Synthesis of Grignards and Other Organometallics 91. Why can we not prepare a Grignard reagent from a molecule such as 4-bromo-1butanol? Ans: Because Grignard reagents are extremely strong bases and will react with the alcohol's acidic proton. Topic: Reactions of Grignards and Other Organometallics 92. A Grignard reagent will produce a primary alcohol when reacted with ____________. Ans: Formaldehyde and ethylene oxide Topic: Reactivity of Grignards and Other Organometallics 93. The reactivity of organometallic compounds increases with the _____________ of the carbon-metal bond. Ans: percent ionic character Topic: Reactions of Grignards and Other Organometallics 94. A Grignard reagent will produce a secondary alcohol when reacted with ____________. Ans: Any aldehyde except formaldehyde 433 Chapter 12 Topic: Reactions of Grignards and Other Organometallics 95. Reaction of an alkyllithium with a ketone produces, after acid work-up, a _____________ alcohol. Ans: tertiary Topic: Reactions of Grignards and Other Organometallics 96. Reaction of excess methyllithium with ethyl acetate (CH3CO2C2H5) produces, after acid work-up, ____________. Ans: t-butyl alcohol: (CH3)3COH Topic: Reactions of Grignards and Other Organometallics 97. Reaction of excess ethyl magnesium bromide with ethyl benzoate (C6H5CO2C2H5) produces, after acid work-up, ____________. OH Ans: 3-phenyl-3-pentanol: Topic: Reactions of Grignards and Other Organometallics 98. Reaction of excess ethyl magnesium iodide with a ethyl acetate (CH3CO2C2H5) produces, after acid work-up, ____________ . Ans: 3-methyl-3-pentanol CH3CH2C(CH3)(OH)CH2CH3 Topic: Redox Reactions 99. In the reaction of carbonyl compounds with LiAlH4, the effective reducing species is: Ans: H− (hydride) Topic: Redox Reactions 100. In the reaction of carbonyl compounds with NaBH4, the effective reducing species is: Ans: H− (hydride) Topic: Grignard Reactions 101. NH4Cl is sometimes preferred instead of HCl or H2SO4 for “acid” work-up after Grignard reactions, particularly when the expected and desired product is a tertiary alcohol: why? Ans: NH4Cl provides mildly acidic conditions via partial hydrolysis of NH4Cl. Under strongly acid conditions, a tertiary alcohol product can undergo facile dehydration to an alkene. 434 Chapter 12 Topic: Synthesis of Grignards and Other Organometallics 102. Diethyl ether, the most commonly used solvent for Grignard reactions, also acts as an ‘internal cooling agent’, preventing the overheating of the reaction mixture: what specific property of diethyl ether is exploited here and why is it important to prevent the overheating of the reaction mixture? Ans: Diethyl ether is very volatile (35-36oC): its low boiling point ensures that reactions carried out in diethyl ether solvent cannot become overheated (the maximum temperature cannot exceed the b.p. of the solvent): this is important in Grignard reactions, because Grignard reagents decompose at higher temperatures. Thus, the decomposition of the newly formed Grignard reagent is minimized by use of this ‘internal cooling agent’. Topic: General 102. When nucleophilic addition to a carbonyl group occurs, the carbon attacked undergoes this hybridization change: Ans: sp2 Æ sp3 Topic: General, Redox 103. PCC and CrO3 are both Cr(VI) reagents. However, PCC/CH2Cl2 is useful in oxidizing primary alcohols to aldehydes, while the analogous reaction with CrO3/H2SO4 will typically produce carboxylic acids. Why? Ans: Both reagents first oxidize the alcohol to the corresponding aldehyde. Further oxidation of aldehydes, to carboxylic acids, is facilitated in aqueous solutions, via formation of the intermediate aldehyde hydrates (CrO3/H2SO4). When the solvent is non-aqueous, such as CH2Cl2, these key intermediates cannot be formed, thereby preventing further oxidation of aldehydes (with PCC/CH2Cl2). Topic: Multistep Reactions 104. What would be the major product, A, of the following reaction? i) NaBH4 ii) NaH, Et2O iii) CF3 O O S A O OCH2CH3 Ans: O 435 Chapter 12 Topic: Multistep Synthetic Strategy 105. Suggest a reasonable synthetic strategy for the synthesis of 3-methyl-3-hexanol from 3hexanol. Ans: 3-hexanol-Æ i) PCC; ii) CH3MgBr (or CH3Li); iii) NH4Cl OH O PCC CH2Cl2 i) CH3MgBr, Et2O ii) NH4Cl OH Topic: Multistep Synthetic Strategy 106. Suggest a reasonable synthetic strategy for the synthesis of 2-methyl-3-hexanol from 1butanol. Ans: 1-butanol Æ i) PCC; ii) (CH3)2CHMgBr (or (CH3)2CHLi); iii) NH4Cl (H3O+) HO PCC CH2Cl2 i) (CH3)2CHMgBr, Et2O ii) NH4Cl O OH Topic: Multistep Synthetic Strategy 107. Suggest a reasonable synthetic strategy for the synthesis of 4-heptanol from 1-pentene. Ans: 1-pentene Æ i)MMPP; ii) CH3CH2MgBr (or CH3CH2Li); iii) NH4Cl (H3O+) MMPP O i) CH3CH2MgBr, Et2O ii) NH4Cl OH Topic: Multistep Synthetic Strategy 108. Suggest a reasonable synthetic strategy for the synthesis of 3-ethyl-3-heptanol from pentanoic acid, CH3CH2CH2CH2CO2H. Ans: CH3CH2CH2CH2CO2H Æ i)SOCl2; ii) 2 equivalents CH3CH2MgBr (or CH3CH2Li); iii) NH4Cl (H3O+) i) CH3CH2MgBr O O OH SOCl2 (2 equivalents), Et2O HO Cl ii) NH4Cl 436 Chapter 12 Topic: Multistep Reaction Sequence 109. Complete the following reaction sequence, giving structural details of all key intermediates. 1-hexene------------------Æ i) HBr ii) Li iii) (CH3CH2)2C=O iv) C2H5I Br Li Ans: HBr Li O OLi O C2H5I Topic: Multistep Reaction Sequence 110. Complete the following reaction sequence, giving structural details of all key intermediates. 2-methyl-1-pentene------------------Æ i) BH3, THF ii) H2O2,NaOH iii) PCC, CH2Cl2 iv) CH3CH2C≡C:−Na+ v) NH4Cl Ans: i) BH3,THF HO ii) H2O2, NaOH PCC, CH2Cl2 i) HO :− Na+ O ii) NH4Cl 437 Chapter 12 Topic: Multistep Reaction Sequence 111. Complete the following reaction sequence, giving structural details of all key intermediates. 4-methyl-1-hexene------------------Æ i) BH3, THF ii) H2O2,NaOH iii) SOCl2 iv) Mg, Et2O iv) ethylene oxide v) NH4Cl Ans: i) BH3,THF HO ii) H2O2, NaOH SOCl2 Mg Et2O ClMg i) Cl O ii) NH4Cl HO 438 Chapter 12 Topic: Multistep Reaction Sequence 112. Complete the following reaction sequence, giving structural details of all key intermediates. Bromocyclohexane------------------Æ i) Li ii) CuI iii) 4-methyl-1-bromohexane Ans: Br Li Li CuI Br 439 CuLi 2 Chapter 13 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. A) B) C) D) E) What is an IUPAC name for 2,3-methylhept-2-en-4-yne 1,1,3-trimethylhex-3-yn-1-ene 1,1,3-trimethyl-3-hexyn-1-ene 2,3-dimethyl-2-hepten-4-yne 5,6-dimethyl-5-hepten-3-yne Ans: D Topic: Nomenclature 2. What is an IUPAC name for this triene? H CH3CH2 A) B) C) D) E) H H CH3 H H H (2E,4Z,6E)–2,4,6–Nonatriene (2Z,4E,6Z)–2,4,6–Nonatriene (2E,4Z,6Z)–2,4,6–Nonatriene (3Z,5Z,7E)–3,5,7–Nonatriene (3Z,5E,7E)–3,5,7–Nonatriene Ans: C Topic: Nomenclature 3. What is an IUPAC name for this triene? A) B) C) D) E) (2E,4Z,6E)–3,4,7,8–tetramethyl-2,4,6–Nonatriene (2Z,4E,6E)–3,4,7,8–tetramethyl-2,4,6–Nonatriene (2E,4Z,6E)–2,3,6,7–tetramethyl-3,5,7–Nonatriene (2E,4Z,6E)– 2,3,6,7–tetramethyl-3,5,7–Nonatriene (2E,4E,6E)–3,4,7,8–tetramethyl-2,4,6–Nonatriene Ans: E 440 Chapter 13 Topic: Nomenclature 4. A correct IUPAC name of the compound below is: Br A) B) C) D) E) 1-Bromo-1-methyl-2,5-cyclohexadiene 3-Bromo-3-methyl-1,4-cyclohexadiene 6-Bromo-6-methyl-1,4-cyclohexadiene 2-Bromo-2-methyl-1,3-cyclohexadiene None of these Ans: B Topic: Stability (Alkenes, Cations, Radicals) 5. A) B) C) D) E) Which of the following dienes would you expect to be the most stable? CH3CH=CHCH=CHCH3 CH3CH=CHCH2CH=CH2 CH2=CHCH2CH2CH=CH2 CH2=CHCH(CH3)CH=CH2 CH3CH=C=CHCH2CH3 Ans: A Topic: Stability (Alkenes, Cations, Radicals) 6. A) B) C) D) E) Which of the following dienes would you expect to be the most stable? CH3CH2CH=CHCH2CH=CHCH3 CH3CH=CHCH=CHCH2CH3 CH2=CHCH2CH2CH2CH=CH2 CH2=CHCH=CHCH2CH2CH3 CH3CH2CH=C=CHCH2CH3 Ans: B 441 Chapter 13 Topic: Stability (Alkenes, Cations, Radicals) 7. Which of the following compounds would be the most stable? I A) B) C) D) E) II III IV I II III IV They are all of equal stability. Ans: A Topic: Stability (Alkenes, Cations, Radicals) 8. Considering both configurational and conformational factors, select the most stable form of 2,4-hexadiene. CH3 H H H H H I A) B) C) D) E) CH3 H H H CH3 H CH3 CH3 II H III I II III IV V Ans: A 442 H H CH3 CH3 H H H CH3 IV H CH3 CH3 V Chapter 13 Topic: Stability (Alkenes, Cations, Radicals) 9. Which alkene would you expect to be most stable? A) CH2=CHCH2CH2CH=CH2 H B) CH2 CHCH2 C C) C H CH2CH CH3 C CH3 CH2 C H H H D) CH3 H C C C C H CH3 H H E) CH3 C C H H C H C CH3 Ans: E Topic: Stability (Alkenes, Cations, Radicals) 10. Which diene would be least stable? I A) B) C) D) E) II III IV I II III IV V Ans: C 443 V Chapter 13 Topic: Stability (Alkenes, Cations, Radicals) 11. Arrange these hexadienes in order of expected decreasing stability. I II IV A) B) C) D) E) III V V > II > I > III > IV III > IV > II > I > V IV > III > II > V > I IV > III > I > II > V I > II > IV > III > V Ans: D Topic: Stability (Alkenes, Cations, Radicals) 12. Which carbocation would be most stable? A) B) C) D) E) Ans: C 444 Chapter 13 Topic: Stability (Alkenes, Cations, Radicals) 13. Which carbocation would be most stable? A) B) C) D) E) CH2 CH3 CH3 CH3 CH3 I II III IV V I II III IV V Ans: C Topic: Stability (Alkenes, Cations, Radicals) 14. Which free radical would be most stable? CH3 A) CH3CC B) C) CH2 CH3 CH2 CCH2CH2 CH3 CH3CCH2CH3 D) E) CH3 CH2CHC CH3 CH2 CH3CHCHCH3 Ans: A 445 Chapter 13 Topic: Stability (Alkenes, Cations, Radicals) V 15. CH3 CH3 A) B) C) D) E) CH CH CH II III Which hydrogen atom(s) of I susceptible to abstraction by free radicals? I II III IV V Ans: D IV CH CH CH3 is/are most Topic: Heat of Hydrogenation 16. Which alkene would you expect to have the smallest heat of hydrogenation? A) CH2=CHCH2CH2CH=CH2 H B) CH2 CHCH2 C C H CH2CH C) CH3 C CH3 CH2 C H H H D) CH3 C C C C H CH3 H H E) CH3 C H C H H C H C CH3 Ans: E 446 Chapter 13 Topic: Bond Lengths 17. A) B) C) D) E) Which compound would have the shortest carbon-carbon single bond? CH3–CH3 CH2=CH–CH3 HC≡C–C≡CH CH2=CH–C≡CH CH2=CH–CH=CH2 Ans: C Topic: Bond Lengths 18. Which compound would have the shortest carbon-carbon single bond? A) B) C) D) E) CH≡C–CH=CH–CH2–CH3 CH2=CH–CH=CH–CH3 HC≡C–CH2–C≡C–CH3 CH2=CH–C≡C–CH2–CH3 CH3–C≡C–C≡C–CH3 Ans: E Topic: Bond Lengths 19. Which carbon-carbon bond in the following compound would you expect to be shortest? H A) B) C) D) E) C C CH I II I II III IV V Ans: A CH III CH2 IV CH3 V 447 Chapter 13 Topic: Bond Lengths 20. Which carbon-carbon bond in the following compound would you expect to be longest? H A) B) C) D) E) C I I II III IV V Ans: E C CH II CH III CH2 IV CH3 V Topic:Alkene Classification 21. Select the structure of the conjugated diene. I A) B) C) D) E) II III IV V I II III IV V Ans: B 448 Chapter 13 Topic:Alkene Classification 22. Select the structure(s) of the conjugated diene(s). II I IV A) B) C) D) E) III V I and II II and III III and IV I, II and V V Ans: B Topic: Alkene Classification 23. A) B) C) D) E) Which of the following dienes is a cumulated diene? CH2=CHCH2CH2CH=CH2 CH2=CHCH=CHCH2CH3 CH3CH=C=CHCH2CH3 CH3CH=CHCH=CHCH3 CH3CH=CHCH2CH=CH2 Ans: C Topic: Alkene Classification 24. A) B) C) D) E) Which of the following dienes is a cumulated diene? CH2=CHCH2CH2CH2CH=CH2 CH2=CHCH=CHCH2CH2CH3 CH3CH=C=CHCH2CH2CH3 CH3CH=CHCH=CHCH2CH3 CH3CH2CH=CHCH2CH=CH2 Ans: C 449 Chapter 13 Topic: Molecular Orbitals 25. A) B) C) D) E) The allyl radical has how many bonding π molecular orbitals? 1 2 3 4 5 Ans: A Topic: Molecular Orbitals 26. A) B) C) D) E) The allyl cation has how many electrons in bonding π molecular orbitals? 1 2 3 4 5 Ans: B Topic: Molecular Orbitals 27. A) B) C) D) E) 1,3-Pentadiene has how many bonding π molecular orbitals? 1 2 3 4 0 Ans: B 450 Chapter 13 Topic: Heat of Hydrogenation 28. Estimate the stabilization energy for 1,3-butadiene using the heats of hydrogenation in Table 1. Table 1. Heats of Hydrogenation for Selected Compounds Compound A) B) C) D) E) 1-Butene 1-Pentene 1,3-Butadiene 1,3-Pentadiene 13 kJ mol-1 15 kJ mol-1 28 kJ mol-1 239 kJ mol-1 112 kJ mol-1 Ans: B Moles H2 ΔH(kJ mol-1) 1 1 2 2 -127 -126 -239 -226 Topic: Resonance 29. Which is not an example of resonance? I CH2=CH−CH2 . II CH2 + CH2 CH2 III . CH2−CH=CH2 + CH3 + . . IV A) B) C) D) E) CH2−CH=CH−CH2CCl3 CH2=CH−CH−CH2CCl3 I II III IV None of these are examples of resonance Ans: C 451 Chapter 13 Topic: Resonance 30. Which is not a proper resonance structure for 1,3-butadiene? A) CH2=CH–CH=CH2 B) CH2 CH CH CH2 C) CH2 CH CH CH2 D) CH2 CH CH CH2 E) All are correct Ans: B Topic: Resonance 31. Which pair does not represent a pair of resonance structures? H I H H H H and H H H H H II III IV A) B) C) D) E) H H H H H and H CH2 CH2 H H H and and H CH2 CH3 I II III IV All of these represent pairs of resonance structures. Ans: D 452 Chapter 13 Topic: Reaction Mechanisms and Control 32. A) B) C) D) E) A thermodynamically-controlled reaction will yield predominantly: the more/most stable product. the product whose formation requires the smallest free energy of activation. the product that can be formed in the fewest steps. the product that is formed at the fastest rate. the product which possesses the greatest potential energy. Ans: A Topic: Reaction Mechanisms and Control 33. A) B) C) D) E) A reaction under kinetic (or rate) control will yield predominantly: the most stable product. the product that can be formed in the fewest steps. the product whose formation requires the smallest free energy of activation. the product with the greatest potential energy. the product with the least potential energy. Ans: C Topic: Reaction Mechanisms and Control 34. The accompanying diagram, which describes the fate of the intermediate in a reversible reaction, implies that: E B A A) B) C) D) E) reaction coordinate the less stable product forms more rapidly. the more stable product forms more rapidly. product B will predominate at equilibrium. the intermediate has a short lifetime. No conclusions can be drawn as to either reaction rate or product stability. Ans: B 453 Chapter 13 Topic: Reaction Mechanisms and Control 35. The accompanying diagram implies that: E B A A) B) C) D) E) reaction coordinate The formation of B from A would be favored at high temperature. The more stable product forms more rapidly from the intermediate species. The formation of the intermediate from A is the rate-limiting step in the transformation of A into B The formation of B from A is not a concerted reaction. All of the above statements are true Ans: E Topic: Diels-Alder Reaction 36. A) B) C) D) E) Which is an untrue statement concerning the Diels-Alder reaction? The reaction is a syn addition. The diene must be in the s-cis conformation to react. Most Diels-Alder reactions are reversible. Generally, the adduct formed most rapidly is the exo product. Depending on the nature of the dienophile, both electron-releasing and electronwithdrawing groups in the diene can favor adduct formation. Ans: D Topic: Diels-Alder Reaction 37. A) B) C) D) E) does not undergo the Diels-Alder reaction because: ring systems cannot function as the diene component. it cannot adopt the s-cis conformation. it lacks electron-withdrawing groups. it lacks strong electron-releasing groups. the two double bonds are further apart than in a non-cyclic conjugated system. Ans: B 454 Chapter 13 Topic: Diels-Alder Reaction 38. A) B) C) D) E) does not undergo the Diels-Alder reaction because: ring systems cannot function as the diene component. it cannot adopt the s-cis conformation. it lacks electron-withdrawing groups. it lacks strong electron-releasing groups. the two double bonds are further apart than in a non-cyclic conjugated system. Ans: B Topic: Diels-Alder Reaction 39. A) B) C) D) E) Which of these dienes is the most reactive in the Diels-Alder reaction? 1,3-Butadiene 1,4-Pentadiene Cyclopentadiene 1,2-Butadiene 1,4-Cyclohexadiene Ans: C Topic: Diels-Alder Reaction 40. A) B) C) D) E) Which of these dienes can undergo the Diels-Alder reaction? 1,3-Pentadiene 1,4-Pentadiene 1,2-Butadiene 1,4-Cyclohexadiene All of the above can undergo the Diels-Alder reaction Ans: A Topic: Diels-Alder Reaction 41. A) B) C) D) E) Which of these dienes can undergo the Diels-Alder reaction? 1,2-Heptadiene 1,3-Heptadiene 1,4-Heptadiene 1,5-Heptadiene 1,6-Heptadiene Ans: B 455 Chapter 13 Topic: Diels-Alder Reaction 42. Which diene and dienophile would you choose to synthesize the following compound? H COCH3 O O and CH2 and CH2 HC I CCOCH3 II O O and and CH2 CH2 CHCOCH3 III A) B) C) D) E) CHCOCH3 IV I II III IV None of these Ans: C Topic: Diels-Alder Reaction 43. Which diene would be least reactive toward Diels-Alder addition of maleic anhydride? CH3 CH2 CH CH CH2 CH2 I CH C CH2 CH2 II IV A) B) C) D) E) CH3 CH3 456 C III V I II III IV V Ans: E C CH2 Chapter 13 Topic: Diels-Alder Reaction 44. What would be the product of the following reaction? O + CH2 A) B) C) D) E) O O C CH 3 C I CHCCH3 O CH3 CH heat C C CH2 CH3 II III I II III IV All of these Ans: C 457 IV CH3 Chapter 13 Topic: Diels-Alder Reaction 45. How would you synthesize: H O COCH3 O O O I 1,3-Cyclohexadiene + CH2 CHCOCH3, then O II RCOOH O 1,3-Cyclohexadiene + RCOOH, then CH2 CHCOCH3, O COCH3 III + CH2 CH2 O O IV 1,4-Cyclohexadiene + CH2 CHCOCH3, O COCH3 V + CH2 CH2 O A) B) C) D) E) I II III IV V Ans: A 458 CH2 CH2 then O Chapter 13 Topic: Diels-Alder Reaction 46. Which of the following would afford a synthesis of the following compound? CHO CHO I 2 CH3CH II CH3CH CHCH3 CH2 + + CHO A) B) C) D) E) III + CH2 CHCHO IV + CH2 CHCHO I II III IV None of these Ans: D 459 Chapter 13 Topic: Diels-Alder Reaction 47. Which diene would you expect to react most rapidly with maleic anhydride? O CH3 CH3 CH3C CH3 CH3 CH3C O I A) B) C) D) E) II III IV V I II III IV V Ans: D Topic: Diels-Alder Reaction 48. Which of these conjugated dienes can undergo a Diels-Alder reaction? (CH3)3C CH2 CH2 CH2 I A) B) C) D) E) II III I II III IV V Ans: C 460 IV C(CH3)3 V Chapter 13 Topic: Diels-Alder Reaction 49. Which of these conjugated dienes can undergo a Diels-Alder reaction? II I IV A) B) C) D) E) III V I and V I, II and V III IV III and IV Ans: D 461 Chapter 13 Topic: Diels-Alder Reaction 50. Which diene and dienophile would you choose to synthesize the following compound? O H COCH3 O O COCH3 and O2 O O and HC I C II O O O and O CH2 CH COCH3 and CH2 III A) B) C) D) E) COCH3 IV I II III IV None of these Ans: C 462 CH COCH3 Chapter 13 Topic: Diels-Alder Reaction 51. Which diene and dienophile would you choose to synthesize the following compound? H CHO H CHO I CHO CHO CHO CHO II III OHC CHO CHO A) B) C) D) E) IV I and VI II and V III and IV IV and V I and III Ans: E CHO V VI 463 Chapter 13 Topic: Diels-Alder Reaction 52. Which compounds could be used in a Diels-Alder synthesis of CH3 CO2CH3 ? CH3 CH3 CH3 CH2 CH3 A) B) C) D) CHCO2CH3 HC CCO2CH3 CH3 I I and III I and IV II and III II and IV Ans: C II III IV Topic: Diels-Alder Reaction 53. Which is the major product of the following reaction? O H C C OH ? + C H C O OH H CO2H I A) B) C) D) E) H H H CO2H CO2H H H CO2H CO2H CO2H H CO2H H II III I II III IV None of these Ans: D 464 CO2H IV Chapter 13 Topic: Diels-Alder Reaction 54. Which is the major product of the following reaction? CHO ? + CHO H CHO H CHO I A) B) C) D) E) CHO H CHO H H CHO CHO H II III CHO H H CHO IV H CHO H CHO V I II III IV V Ans: A Topic: Diels-Alder Reaction 55. Which is the major product of the following reaction? + I A) B) C) D) E) H CHO CHO H CHO H CHO H H CHO H CHO II ? CHO OHC III I II III IV V Ans: D 465 CHO CHO IV CHO CHO V Chapter 13 Topic: Diels-Alder Reaction 56. Which is the major product of the following reaction? + CHO H CHO H H CHO H CHO I A) B) C) D) E) II ? CHO CHO III I II III IV V Ans: III 466 CHO IV CHO V Chapter 13 Topic: Diels-Alder Reaction 57. Which diene and dienophile would you choose to synthesize the following compound? O COCH3 O O COCH3 and O2 O O and HC I C II O O and O CH2 CH and COCH3 CH2 III A) B) C) D) E) IV I II III IV None of these Ans: B Topic: Diels-Alder Reaction 58. Which of the following can undergo the Diels Alder reaction? II I IV A) B) C) D) E) COCH3 III V I and II II and III III and IV I, II and V V Ans: C 467 CH COCH3 Chapter 13 Topic: Diels-Alder Reaction 59. From the standpoint of reactivity, which is the poorest choice of dienophile to react with 2,3-dimethyl-1,3-butadiene in a Diels-Alder reaction? O O I O II H3CO III O O H3CO O OCH3 IV A) B) C) D) E) OCH3 O V I II III IV V Ans: B 468 Chapter 13 Topic: Diels-Alder Reaction 60. What is the product of the following reaction? CH CH2 O + O ? CH3C C C CCH3 COCH3 COCH3 COCH3 COCH3 COCH3 I COCH3 II III COCH3 COCH3 COCH3 COCH3 IV A) B) C) D) E) V I II III IV V Ans: A 469 Chapter 13 Topic: Diels-Alder Reaction 61. Which would be the best synthesis of the following compound? CO2CH3 CO2CH3 CO2CH3 CO2CH3 CO2CH3 + + + CO2CH3 CO2CH3 I CH3O2C II III CO2CH3 + + 2 HCO2CH3 CO2CH3 IV A) B) C) D) E) V I II III IV V Ans: B 470 Chapter 13 Topic: Diels-Alder Reaction 62. Which reaction would produce the following compound? H CO2CH3 CO2CH3 H H CO2CH3 CO2CH3 H CO2CH3 + + CH3O2C H I H II CO2CH3 + H CO2CH3 H CO2CH3 + H CO2CH3 III A) B) C) D) E) H IV I II III IV None of the above Ans: D 471 Chapter 13 Topic: Diels-Alder Reaction 63. Which of the following pairs of compounds could be used as the basis for a Diels-Alder synthesis of the compound shown below? CO2CH3 CO2CH3 I 2 CH3CH CHCH3 + II III CH3CH CH2 + CH2 CHCO2CH3 + CO2CH3 IV A) B) C) D) E) + CH2 CHCO2CH3 I II III IV More than one of the above Ans: D 472 Chapter 13 Topic: Multi-step Synthesis 64. How could the following synthesis be carried out? CH2CH3 A) B) C) D) E) (1) Br2/CCl4; (2) CH3CH2MgCl, ether; (3) CH3ONa/CH3OH (1) HBr, 80°C; (2) (CH3CH2)2CuLi, ether (1) HBr, 80°C; (2) Mg, ether; (3) CH3CH2OH, then H3O+ More than one of the above All of the above Ans: B Topic: Multi-step Reaction Sequence 65. How could the following synthesis be carried out? A) B) C) D) E) (1) Br2/CCl4; (2) CH3MgCl, ether; (3) CH3ONa/CH3OH (1) HBr (1 eq); (2) (CH3)2CuLi, ether (1) HBr (1eq); (2) Li, ether; (3) CuI; (4) CH3Br More than one of the above All of the above Ans: C Topic: Allylic Substitution 66. What product(s) would you expect from the following substitution reaction of 14Clabeled propene? Cl2 14CH 2 CH CH3 ? 500 oC A) 14CH2=CH–CH2Cl alone B) 14CH2=CH–CH2Cl and CH2=CH–14CH2Cl, in equal amounts C) CH2=CH–14CH2Cl alone D) more 14CH2=CHCH2Cl, but a little CH2=CH–14CH2Cl E) more CH2=CH–14CH2Cl, but a little 14CH2=CHCH2Cl Ans: B 473 Chapter 13 Topic: Allylic Substitution 67. What product(s) would you expect from the following substitution reaction? * Cl2 ? 500oC Cl Cl Cl * I A) B) C) D) E) * II Cl * III * IV I II III IV More than one of the above Ans: E Topic: Synthesis of Allylic Halides 68. Which of the following could be used to synthesize 3-bromopropene? A) 25 oC CH3CH CH2 + Br2 CCl4 ROOR B) CH3CH CH2 + N-bromosuccinimide CCl4 C) CH2=CHCH2OH + PBr3 ⎯⎯⎯⎯→ D) More than one of these E) None of these Ans: D Topic: Synthesis of Allylic Halides 69. A) B) C) D) E) Which of the following could be used to synthesize 3-bromocyclopentene? Cyclopentene + Br2, CCl4 , 25o Cyclopentene + NBS, CCl4 (ROOR) 3-Cyclopentenol + PBr3 Both A) and B) Both B) and C) Ans: E 474 Chapter 13 Topic: Synthesis of Allylic Halides 70. Treatment of 2-butene (cis or trans) with N-bromosuccinimide in CCl4 would yield mainly: A) CH3CHBrCHBrCH3 alone B) CH3CH=CBrCH3 alone C) CH3CH=CHCH2Br alone D) CH2BrCH2CH=CH2 and CH3CH=CHCH2Br E) CH3CHBrCH=CH2 and CH3CH=CHCH2Br Ans: E Topic: Synthesis of Allylic Halides 71. Treatment of 4-methylcyclohexene with N-bromosuccinimide in CCl4 would yield mainly: Br Br Br Br I A) B) C) D) E) II III I II III IV All of the above Ans: E 475 IV Chapter 13 Topic: Multistep Reactions 72. Which would be the best synthesis? ? CH2 CHCH3 CH2CHCH2Cl Br Br A) Propene B) Propene C) D) E) Propene Propene Propene Ans: B Cl2, hν Br2, CCl4 Cl2, 400 oC Br2, CCl4 Br2, hν HCl NBS, CCl4 Cl2, CCl4 NBS, CCl4 Cl2, CCl4 Topic: Ozonolysis of Polyenes 73. Which is the diene that yields on ozonolysis (O3, followed by Zn/HOAc) an equimolar CHO CH2 mixture of CH2O, CH3CHO, and CHO CH2 CH CH CH CH2 CH3 CH3 I CH2 III II CH CH2 CH CH CH3 CH2 IV A) B) C) D) E) CH CH2 CH2 V I II III IV V Ans: D 476 CH CH2 Chapter 13 Topic: Allylic Halogenation 74. What is (are) the product(s) of the following reaction? Cl2 ? 400oC Cl Cl Cl I A) B) C) D) E) II III I II III a mixture of I and II a mixture of II and III Ans: E Topic: Allylic Halogenation 75. A) B) C) D) E) Which set of conditions does not result in allylic halogenation of an alkene? Cl2 at 400°C Cl2 in CCl4 at 25°C Cl2, ROOR,hν Br2 at low concentration in CCl4 N-Bromosuccinimide in CCl4, ROOR Ans: B Topic: Allylic Halogenation CH3 76. CH3 A) B) C) D) E) CH CH2 CH CH2 IV III II I is predicted to be the major site of Which carbon of V substitution when this alkene reacts with chlorine at 400°C? I II III IV V Ans: C 477 Chapter 13 Topic: Allylic Halogenation 77. Which carbon is predicted to be the major site of substitution when this alkene reacts with NBS? V I A) B) C) D) E) III IV II I II III IV V Ans: B Topic: Diene Synthesis 78. A) B) C) D) E) Which of these is not a useful method for the synthesis of 1,3-pentadiene? 1,4-pentanediol + H2SO4 at 180oC 2,4-dibromopentane + (CH3)3COK , (CH3)3COH at 75oC 2,4-pentanediol + H2SO4 at 180oC HC≡CCH=CHCH3 + H2, Ni2B (P-2) 1,4-dibromopentane + CH3CH2ONa , CH3CH2OH at 75oC Ans: B 478 Chapter 13 Topic: Conjugate Addition Reactions 79. Ignoring stereochemistry, the 1:1 reaction of bromine with 1,3-cyclohexadiene at 25°C in the dark and in the absence of peroxide forms which of these? Br Br Br Br Br I A) B) C) D) E) Br II III Br IV I II III IV Both I and II Ans: E Topic: Conjugate Addition Reactions 80. Which is the only compound which can be completely ruled out as a product of the reaction of 1,3-butadiene with HCl? A) (S)-3-chloro-1-butene B) (R)-3-chloro-1-butene C) (E)-1-chloro-2-butene D) (Z)-1-chloro-2-butene E) (Z)-2-chloro-2-butene Ans: E Topic: Diene Synthesis 81. Hot alumina can be used as an effective dehydrating agent: when 3-methyl-2,3pentanediol vapor is passed over hot alumina (Al2O3), the chief product to be expected is which of these? A) 2-Ethyl-1,3-butadiene B) 3-Methyl-1,3-pentadiene C) 3-Methyl-1,2-pentadiene D) 3-Methyl-2,3-pentadiene E) 3-Methyl-1,4-pentadiene Ans: B 479 Chapter 13 Topic: Allylic Halogenation 82. A) B) C) D) E) An unsaturated product results from the reaction of cyclohexene with which of these? Br2/CCl4 at 25°C NBS/CCl4, ROOR HCl, ROOR HCl, no peroxides More than one of these Ans: B Topic: Conjugate Addition Reactions 83. Which of the following dienes might react with bromine in CCl4 to yield 2,5-dibromo-3hexene? A) CH2=CHCH2CH2CH=CH2 B) CH2=CHCH=CHCH2CH3 C) CH3CH=C=CHCH2CH3 D) CH3CH=CHCH=CHCH3 E) CH3CH=CHCH2CH=CH2 Ans: D Allylic Halogenation 84. What product(s) would you expect from the following substitution reaction of 14Clabeled propene? N-bromosuccinimide 14CH 2 CH ? CH3 ROOR, CCl4 A) 14CH2=CH–CH2Br alone B) 14CH2=CH–CH2Br and CH2=CH–14CH2Br in equal amounts C) CH2=CH–14CH2Br alone D) More 14CH2=CHCH2Br but a little CH2=CH–14CH2Br E) More CH2=CH14CH2Br but a little 14CH2=CHCH2Br Ans: B 480 Chapter 13 Allylic Halogenation 85. A) B) C) D) E) Treatment of 2-butene (cis or trans) with Cl2 at 400°C would yield mainly: CH2ClCHClCH2CH3 CH3CHClCH2CH3 CH3CH=CClCH3 CH3CH=CHCH2Cl and CH3CHClCH=CH2 CH3CHClCHClCH3 Ans: D Topic: Conjugate Addition Reactions 86. Indicate which products would be obtained from the chlorination of 1,5-hexadiene at high temperature (500°C), using a 1:1 mole ratio of the reactants. ClCH2CHCH2CH2CH ClCH2CH CH2 CHCH CHCH2Cl Cl I II ClCH2CH CHCH2CH CH2 III CH2 CHCH2CHCH Cl CH2 ClCH2CHCH2CH2CHCH2Cl IV A) B) C) D) E) Cl Cl V I and II II and III III and IV IV and V V and I Ans: C 481 Chapter 13 Topic: 1,2 Reactions of Conjugated Dienes 87. Which reagent would convert 1,3-pentadiene into 3-penten-2-ol? A) B) C) D) E) KMnO4/-OH OsO4 H2O2, then H3O+ Cl2/H2O H3O+ Ans: E Topic: 1,2 Reactions of Conjugated Dienes 88. A) B) C) D) E) Which reagent would convert 1,3-octadiene into 3-octen-2-ol? KMnO4/-OH OsO4 H2O2, then H3O+ Cl2/H2O H3O+ Ans: E Topic: UV-Vis Spectroscopy 89. Which compound would have an UV absorption band at longest wavelength? CHCH CH CH CHCH3 I II CH2CH CH2 III CH IV A) B) C) D) E) CH2 V I II III IV V Ans: B 482 CHCH3 CHCH3 Chapter 13 Topic: UV-Vis Spectroscopy 90. A) B) C) D) E) Select the most energetically favorable UV transition for 1,3-butadiene. n ⎯⎯⎯→ σ* n ⎯⎯⎯→ π* π2 ⎯⎯⎯→ π3* σ ⎯⎯⎯→ σ* π1 ⎯⎯⎯→ π4* Ans: C Topic: UV-Vis Spectroscopy 91. Which compound would have an UV absorption band at longest wavelength? CH CHCH CH2 CH I CHCH CH II CH2CH2CH CH2 CHCH CH2 III CH IV A) B) C) D) E) CH2 CHCH CH2 V I II III IV V Ans: A Topic: UV-Vis Spectroscopy 92. Which of these symbols is used in connection with the intensity of absorption in the UV-visible region? A) ∝ B) ν C) ε D) λ E) θ Ans: C 483 Chapter 13 Topic: Allylic Halogenation 93. Which of the following compounds is not formed as a result of a chain-termination step in the free radical chlorination of propene? A) CH2=CHCH2Cl B) Cl2 C) CH2=CHCH2CH2CH=CH2 D) HCl E) All can be formed in chain-termination steps. Ans: D SHORT ANSWER QUESTIONS Topic: General 94. Systems that have a p orbital on an atom adjacent to a double bond are called ______________ systems. Ans: conjugated unsaturated Topic: General 95. The hydrogen atom on a saturated (sp3) carbon adjacent to a double bond is called an ______________ hydrogen. Ans: allylic Topic: General 96. The hydrogen atom on a carbon that is part of a double bond is called a ___________ hydrogen. Ans: vinyl or vinylic Topic: General 97. Allylic radicals are ___________ stable than tertiary radicals. Ans: more Topic: General 98. Vinyl cations are _____________ stable than tertiary cations. Ans: less 484 Chapter 13 Topic: General 99. There are three types of polyenes (molecules containing two or more double bonds). They are: _________________. Ans: conjugated, cumulated, isolated Topic: General 100. Polyenes in which single and double bonds alternate along the carbon chain are called ___________. Ans: conjugated Topic: General 101. UV-vis spectroscopy can be used to indicate whether _________________ is present. Ans: conjugation Topic: General 102. When the product distribution for a particular reaction reflects the relative stabilities of the products, the reaction is said to be under ______________ control. Ans: thermodynamic Topic: General 103. When the product distribution for a particular reaction reflects the relative rate at which the products are formed, the reaction is said to be under _______________ control. Ans: kinetic Topic: General 104. The Diels-Alder reaction is a cycloaddition between a conjugated ________ and a ___________. Ans: diene; dienophile Topic: General 105. A thermodynamically-controlled reaction will yield predominantly:___________. Ans: the more/most stable product. Topic: General 106. A reaction under kinetic (or rate) control will yield predominantly:___________. Ans: the product whose formation requires the smallest free energy of activation. 485 Chapter 13 Topic: General 107. Stereochemically speaking, the Diels-Alder reaction is ___________ and occurs with ___________ of the dienophile stereochemistry. Ans: stereospecific; retention Topic: General 108. Conjugated dienes routinely undergo 1,2 and 1,4 addition reactions with a variety of electrophilic reagents; this suggests that ___________ are likely intermediates during these reactions. Ans: allylic carbocations Topic: Diels –Alder Reactions 109. During Diels Alder reactions, when two stereoisomer products, exo and endo, are possible, the ___________ product is typically obtained as the major product. Ans: endo Topic: Nomenclature 110. Draw the structural formula for (2E,4Z,6E)–3,4,7,8–tetramethyl-2,4,6–nonatriene, clearly indicating stereochemical details. Ans: Topic: Nomenclature 111. Draw the structural formula for (2Z,4Z,6Z)-3,4,8-trimethyl-2,4,6-nonatriene,clearly indicating stereochemical details. Ans: Topic: Nomenclature 112. Draw the structural formula for (R)-5-bromo-2,5-dimethyl-1,3-cyclopentadiene, clearly indicating stereochemical details. CH3 Ans: Br 486 Chapter 13 Topic: Multistep Reactions 113. Complete the following sequence of reactions, giving structural details of all key intermediates. O heat + A O H2 Ni B Ans: O O O heat + + O O O H2, Ni O O + O O + + O O + O 487 O Chapter 13 Topic: Multistep Reactions 114. Complete the following sequence of reactions, giving structural details of all key intermediates. i) NBS ii) (CH3)3COK, (CH3)3COH, heat iii) trans CH3CH=CHCHO ? Br Ans: (CH3)3COK, (CH3)3COH, heat NBS O O + O Topic: Multistep Reactions 115. Complete the following sequence of reactions, giving structural details of all key intermediates. i) cis-CH3CH=CHCHO ? ii) CH3CH2MgBr + iii) H3O Ans: H H CHO CH3 H i) CH3CH2MgBr CH3 H ii) H3O+ O HO Topic: Diels Alder Reaction 116. What reagents would be needed to synthesize the following substance via the DielsAlder reaction? Give stereochemical details, as relevant. O O O O Ans: + O O 488 Chapter 14 MULTIPLE CHOICE QUESTIONS Topic: Bonding and Resonance 1. Which of the following is NOT true of benzene? A) Benzene tends to undergo substitution rather than addition reactions, even though it has a high index of hydrogen deficiency. B) All of the hydrogen atoms of benzene are equivalent. C) The carbon-carbon bonds of benzene are alternately short and long around the ring. D) Only one o-dichlorobenzene has ever been found. E) Benzene is more stable than the hypothetical compound 1,3,5-cyclohexatriene. Ans: C Topic: Bonding and Resonance 2. A) B) C) D) E) Which of the following is true of benzene? Benzene tends to undergo addition rather than substitution reactions. All of the hydrogen atoms of benzene are equivalent. The carbon-carbon bonds of benzene are alternately short and long around the ring. The benzene ring is a distorted hexagon. Benzene has the stability expected for cyclohexatriene. Ans: B Topic: Bonding and Resonance 3. A) B) C) D) E) The carbon-carbon bonds in benzene are: of equal length and are shorter than the double bond of ethene. of equal length and are intermediate between a double bond and a single bond. of unequal length and are alternately short and long around the ring. due only to p-orbital overlap. of equal length and intermediate between the carbon-carbon bond lengths in ethene and ethyne. Ans: B Topic: Nomenclature, Bonding and Resonance 4. In which of the following compounds would the shortest carbon-carbon bond(s) be found? A) Toluene B) 2-Ethylcyclopentene C) 4-Methyl-1,3-cyclohexadiene D) 3-Methyl-1-hexyne E) 3-Methyl-1,3-hexadiene Ans: D Page 489 Chapter 14 Topic: Bonding and Resonance 5. We now know that the two Kekule structures for benzene are related in the following way: A) They are each equally correct as a structure for benzene. B) Benzene is sometimes one structure and sometimes the other. C) The two structures are in a state of rapid equilibrium. D) Neither of the two structures adequately describes benzene; benzene is a resonance hybrid of the two. E) None of the above Ans: D Topic: Nomenclature, Bonding and Resonance 6. In which of the following compounds would the longest carbon-carbon bond(s) be found? A) 2-bromobenzaldehyde B) Vinylbenzene C) 1,3,5-heptatriene D) 2,4,6-octatriene E) 2-Ethylbenzoic acid Ans: D Topic: Aromatic/ Antiaromatic/ Nonaromatic 7. A) B) C) D) E) Which of the following statements regarding the cyclopentadienyl radical is correct? It is aromatic. It is not aromatic. It obeys Huckel's rule. It undergoes reactions characteristic of benzene. It has a closed shell of 6 pi-electrons. Ans: B 490 Chapter 14 Topic: Aromaticity, Huckel Rule 8. Which of the following would you expect to be aromatic? H H A) B) C) D) E) I I II III IV V Ans: E II III IV V Topic: Aromaticity, Huckel Rule 9. Which of these would you expect to have significant resonance stabilization energy? N H A) B) C) D) E) N I II I II III All of the above None of the above Ans: D III 491 Chapter 14 Topic: Aromaticity, Huckel Rule 10. Of the following C-10 compounds, which is expected to possess the greatest resonance (delocalization) energy? I A) B) C) D) E) II III IV I II III IV V Ans: C Topic: Aromaticity, Huckel Rule 11. Which of the following would you expect to be aromatic? H H A) B) C) D) E) I I II III IV None of these Ans: B II III IV 492 V Chapter 14 Topic: Aromaticity, Huckel Rule 12. Which compound would you NOT expect to be aromatic? N A) B) C) D) E) I I II III IV V Ans: E S N H O B R II III IV V Topic: Aromaticity, Huckel Rule 13. A) B) C) D) E) Which annulene would you NOT expect to be aromatic? [6]-Annulene [14]-Annulene [16]-Annulene [18]-Annulene [22]-Annulene Ans: C Topic: Aromaticity, Huckel Rule 14. Which of the following would you expect to be aromatic? A) B) C) D) E) I II I II III IV All of these Ans: A III IV 493 Chapter 14 Topic: Aromaticity, Huckel Rule 15. Which of these species is aromatic? A) B) C) D) E) O O N H O N H O S I I II III IV V Ans: B II III IV V Topic: Aromaticity, Huckel Rule 16. Which of the following structures would be aromatic? K -2 K Br Br 2K A) B) C) D) E) I I II III IV V Ans: B II III 494 IV V Chapter 14 Topic: Aromaticity, Huckel Rule 17. Which of the following would you expect to be antiaromatic? A) B) C) D) E) I I II III IV V Ans: C II III IV V Topic: Aromaticity, Huckel Rule 18. Which of the following would you expect to be aromatic? H H I A) B) C) D) E) II III IV I II III IV None of the above Ans: C 495 Chapter 14 Topic: Aromaticity, Huckel Rule 19. On the basis of molecular orbital theory and Huckel's rule, which molecules and/or ions should be aromatic? I H H H II III H IV V N H A) B) C) D) E) H VI VII I and V III and VIII IV, VII and IX IV, VI, VII and IX All of the structures, I-IX Ans: D H H VIII IX Topic: Aromaticity, Huckel Rule 20. On the basis of molecular orbital theory and Huckel's rule, which of these compounds should be aromatic? H H A) B) C) D) E) I I II III IV V Ans: E II III IV V 496 Chapter 14 Topic: Aromaticity, Huckel Rule 21. Of Huckel's requirements for aromatic character, only this one is waived in the case of certain compounds considered to be aromatic. A) The ring system must be planar. B) The system must be monocyclic. C) There must be (4n + 2) π electrons. D) The Huckel number of electrons must be completely delocalized. E) None. All of these rules must apply in every case. Ans: B Topic: Aromaticity, Huckel Rule 22. Which of these is an aromatic molecule? N O B CH3 A) B) C) D) E) I I II III IV V Ans: A CH3 II III N S H O IV V Topic: Aromaticity, Huckel Rule 23. In which case is the indicated unshared pair of electrons NOT a contributor to the π aromatic system? N H A) B) C) D) E) O N I II I II III IV None of these Ans: B H III IV 497 Chapter 14 Topic: Chemical Tests and Reactions 24. Which reagent(s) would serve as the basis for a simple chemical test that would distinguish between benzene and 1-hexene? A) NaOH in H2O B) Br2 in CCl4 C) AgNO3 in C2H5OH D) NaHSO3 in H2O E) None of these Ans: B Topic: Chemical Tests and Reactions 25. Which reagent(s) would serve as the basis for a simple chemical test that would distinguish between ethylbenzene and vinylcyclohexane? A) H2CrO4 B) LAH C) NaBH4, H2O D) KMnO4, OH−, H2O E) Two of the above Ans: D Topic: Chemical Tests and Reactions 26. Which reagent(s) would serve as the basis for a simple chemical test that would distinguish between naphthalene and 2,4,6-decatriene? A) NaOH in H2O B) KMnO4, OH−, H2O C) NaBH4, H2O D) H2CrO4 E) None of these Ans: B Topic: Chemical and Spectroscopic Analysis 27. Which reagent(s)/technique would serve to distinguish between azulene and bicyclo[5.3.0]decane? A) B) C) D) E) Br2, CCl4 KMnO4, OH−, H2O NMR Spectroscopy UV Spectroscopy Two of these Ans: E 498 Chapter 14 Topic: Chemical Tests and Reactions 28. Which is the only one of these reagents which will react with benzene under the specified conditions? A) Cl2, FeCl3, heat B) H2, 25°C C) Br2/CCl4, 25°C, dark D) KMnO4/H2O, 25°C E) H3O+, heat Ans: A Topic: Nomenclature and Isomerism 29. A) B) C) D) E) Which dibromobenzene can, in theory, yield three mononitro derivatives? o-Dibromobenzene m-Dibromobenzene p-Dibromobenzene All of these None of these Ans: B Topic: Nomenclature and Isomerism 30. If thiophene is an aromatic molecule and reacts similarly to benzene, how many (neutral) monobromothiophenes could be obtained in the following reaction? S A) B) C) D) E) Br2 FeBr3 1 2 3 4 5 Ans: B 499 Chapter 14 Topic: Nomenclature and Isomerism 31. 2-Bromo-4-nitroaniline is: Br Br NH2 NO2 Br NO2 NH2 NO2 I II H2N III OCH3 Br Br A) B) C) D) E) H3CO NO2 NO2 IV V I II III IV V Ans: C Topic: Nomenclature and Isomerism 32. 4-Bromo-2-nitroaniline is: Br Br NH2 NO2 Br NO2 NH2 NO2 I II H2N III OCH3 Br A) B) C) D) E) Br H3CO NO2 NO2 IV V I II III IV V Ans: A 500 Chapter 14 Topic: Nomenclature and Isomerism 33. 4-Amino-2-chlorophenol is: Cl OH Cl O O Cl NH2 NO2 I II H2N III OH OH Cl A) B) C) D) E) Cl NH2 NO2 IV V I II III IV V Ans: D Topic: Nomenclature and Isomerism 34. 4-Chloro-3-nitro-benzaldehyde is: Cl OH Cl O O Cl NH2 NO2 I II H2N III OH Cl A) B) C) D) E) OH Cl NH2 NO2 IV V I II III IV V Ans: B 501 Chapter 14 Topic: Nomenclature and Isomerism 35. 4-amino-2-chlorobenzaldehyde is: Cl OH Cl O O Cl NH2 NO2 I II H2N III OH OH Cl A) B) C) D) E) Cl NH2 NO2 IV V I II III IV V Ans: C Topic: Nomenclature and Isomerism 36. 4-amino-2-bromoanisole is: Br Br Br OCH3 O H3CO NH2 NO2 I II H2N III OCH3 Br A) B) C) D) E) OCH3 Br NH2 NO2 IV V I II III IV V Ans: D 502 Chapter 14 Topic: Nomenclature and Isomerism 37. 4-bromomethyl-2-nitroanisole is: Br Br Br OCH3 O H3CO NH2 NO2 I II H2N III OCH3 Br A) B) C) D) E) OCH3 Br NH2 NO2 IV V I II III IV V Ans: B Topic: Nomenclature and Isomerism 38. A) B) C) D) E) How many different dibromophenols are possible? 8 7 6 5 4 Ans: C Topic: Nomenclature and Isomerism 39. The correct name for the compound shown below is: Br Br NH2 A) B) C) D) E) 3,4-Dibromoaniline 2,4-Dibromoaniline 2,5-Dibromoaniline 3,6-Dibromoaniline 2,6-Dibromoaniline Ans: C 503 Chapter 14 Topic: Nomenclature and Isomerism 40. A) B) C) D) E) Which dibromobenzene can yield only one mononitro derivative? o-Dibromobenzene m-Dibromobenzene p-Dibromobenzene More than one of these None of these Ans: C Topic: Nomenclature and Isomerism 41. A dichlorobenzene that on reaction with nitric acid and sulfuric acid might theoretically yield three mononitro products would be: A) o-Dichlorobenzene B) m-Dichlorobenzene C) p-Dichlorobenzene D) None of these E) All of these Ans: B Topic: Nomenclature and Isomerism 42. A) B) C) D) E) In theory, a single molecule of this compound will rotate plane-polarized light. Butylbenzene Isobutylbenzene sec-Butylbenzene tert-Butylbenzene None of these Ans: C 504 Chapter 14 Topic: Nomenclature and Isomerism 43. Which of the following is NOT 2-bromo-5-nitrobenzoic acid? Br Br HO OH O2 N NO2 O O O I Br II Br III HO HO NO2 IV A) B) C) D) E) V I II III IV V Ans: D Topic: Nomenclature and Isomerism 44. A) B) C) D) E) Toluene is the name commonly assigned to: Hydroxybenzene Aminobenzene Methylbenzene Ethylbenzene Methoxybenzene Ans: C Topic: Nomenclature and Isomerism 45. A) B) C) D) E) O Br O NO2 HO Anisole is the name commonly assigned to: Hydroxybenzene Aminobenzene Methylbenzene Ethylbenzene Methoxybenzene Ans: E 505 Chapter 14 Topic: Nomenclature and Isomerism 46. A) B) C) D) E) Phenol is the name commonly assigned to: Hydroxybenzene Aminobenzene Methylbenzene Ethylbenzene Methoxybenzene Ans: A Topic: Nomenclature and Isomerism 47. A) B) C) D) E) Aniline is the name commonly assigned to: Hydroxybenzene Aminobenzene Methylbenzene Ethylbenzene Methoxybenzene Ans: B Topic: Nomenclature and Isomerism 48. The complete name for the following compound is: CH3 H A) B) C) D) E) sec-Hexylbenzene 2-Phenylhexane (R)-2-Phenylhexane (S)-2-Phenylhexane Butylmethylphenylmethane Ans: D Topic: Nomenclature and Isomerism 49. A) B) C) D) E) How many dichloronaphthalenes are possible? 7 8 9 10 12 Ans: D 506 Chapter 14 Topic: Nomenclature and Isomerism 50. Which of these is the single best representation for naphthalene? II I IV A) B) C) D) E) III V I II III IV V Ans: A Topic: Molecular Orbital Theory 51. How many equivalent resonance structures can be written for the cyclopentadienyl anion? A) 3 B) 4 C) 5 D) 6 E) 7 Ans: C Topic: Molecular Orbital Theory 52. In the molecular orbital model of benzene, the six p-orbitals combine to form how many molecular orbitals? A) 6 B) 5 C) 4 D) 3 E) 2 Ans: A 507 Chapter 14 Topic: Molecular Orbital Theory 53. Consider the molecular orbital model of benzene. In the ground state how many molecular orbitals are filled with electrons? A) 1 B) 2 C) 3 D) 4 E) 5 Ans: C Topic: Molecular Orbital Theory 54. In the molecular orbital model of benzene, how many pi-electrons are delocalized about the ring? A) 2 B) 3 C) 4 D) 5 E) 6 Ans: E Topic: Molecular Orbital Theory 55. In the molecular orbital model of benzene, how many pi-electrons are in bonding molecular orbitals? A) 6 B) 5 C) 4 D) 3 E) 2 Ans: A Topic: Molecular Orbital Theory 56. Consider the molecular orbital model of cyclopentadienyl anion. In the ground state how many molecular orbitals are filled with electrons? A) 1 B) 2 C) 3 D) 4 E) 5 Ans: C 508 Chapter 14 Topic: Molecular Orbital Theory 57. In the molecular orbital model of cyclopentadienyl anion, how many pi-electrons are delocalized about the ring? A) 2 B) 3 C) 4 D) 5 E) 6 Ans: E Topic: Molecular Orbital Theory 58. In the molecular orbital model of cyclopentadienyl anion, how many pi-electrons are in bonding molecular orbitals? A) 6 B) 5 C) 4 D) 3 E) 2 Ans: A Topic: Molecular Orbital Theory 59. In the molecular orbital model of cycloheptadienyl cation, how many pi-electrons are in bonding molecular orbitals? A) 6 B) 5 C) 4 D) 3 E) 2 Ans: A Topic: Molecular Orbital Theory 60. In the molecular orbital model of cycloheptadienyl cation, how many pi-electrons are delocalized about the ring? A) 6 B) 5 C) 4 D) 3 E) 2 Ans: A 509 Chapter 14 Topic: Molecular Orbital Theory 61. In the molecular orbital model of 1,3-cyclobutadiene, how many electrons are in nonbonding molecular orbitals? A) 6 B) 5 C) 4 D) 3 E) 2 Ans: E Topic: Molecular Orbital Theory 62. In the molecular orbital model of which of the following substance(s) are non-bonding orbitals found? A) 1,3-Cyclobutadiene B) Cyclopentadienyl anion C) 1,3,5,7-Cyclooctatetraene D) Two of the above E) All of the above Ans: D Topic: Molecular Orbital Theory 63. Which cyclization(s) should occur with a decrease in pi-electron energy? A) B) C) D) E) I CH2 CH CH II CH2 CH CH2 III CH2 CH CH2 IV CH2 CH CH2 CH2 + H2 + H2 + H2 + H2 I II III IV All of the above Ans: B 510 Chapter 14 Topic: Molecular Orbital Theory 64. Application of the polygon-and-circle technique reveals that single electrons occupy each of the two nonbonding orbitals in the molecular orbital diagram of: A) Cyclobutadiene B) Benzene C) Cyclopropenyl cation D) Cyclopentadienyl anion E) Cycloheptatrienyl cation Ans: A Topic: Explanations and Predictions 65. A) B) C) D) E) Why would 1,3-cyclohexadiene undergo dehydrogenation readily? It is easily reduced. Hydrogen is a small molecule. 1,3-Cyclohexadiene has no resonance energy. It would gain considerable stability by becoming benzene. It would not undergo dehydrogenation. Ans: D Topic: Explanations and Predictions 66. A) B) C) D) E) Which of the following statements about cyclooctatetraene is NOT true? The compound rapidly decolorizes Br2/CCl4 solutions. The compound rapidly decolorizes aqueous solutions of KMnO4. The compound readily adds hydrogen. The compound is nonplanar. The compound is comparable to benzene in stability. Ans: E Topic: Explanations and Predictions 67. Cyclopentadiene is unusually acidic for a hydrocarbon. An explanation for this is the following statement. A) The carbon atoms of cyclopentadiene are all sp2-hybridized. B) Cyclopentadiene is aromatic. C) Removal of a proton from cyclopentadiene yields an aromatic anion. D) Removal of a hydrogen atom from cyclopentadiene yields a highly stable free radical. E) Removal of a hydride ion from cyclopentadiene produces an aromatic cation. Ans: C 511 Chapter 14 Topic: Explanations and Predictions 68. Recalling that benzene has a resonance energy of 152 kJ mol-1 and naphthalene has a resonance energy of 255 kJ mol-1, predict the positions which would be occupied by bromine when phenanthrene (below) undergoes addition of Br2. 3 4 5 6 2 7 1 8 10 A) B) C) D) E) 9 1, 2 1, 4 3, 4 7, 8 9, 10 Ans: E Topic: Spectroscopy 69. Which isomer of C7H7Cl exhibits strong IR absorbances at 690 and 750 cm1? CH3 CH3 CH3 CH2Cl Cl Cl Cl I A) B) C) D) E) II III IV I II III IV II and IV Ans: E 512 Chapter 14 Topic: Spectroscopy 70. Which of these compounds absorbs at the longest wavelength in the UV-visible region? I A) B) C) D) E) II III IV V I II III IV V Ans: B Topic: Spectroscopy 71. A compound has the formula C8H9Br. Its 1H NMR spectrum consists of: doublet, δ 2.0 quartet, δ 5.15 multiplet, δ 7.35 The IR spectrum shows two peaks in the 680-840 cm-1 region; one is between 690 and 710 cm-1 and the other is between 730 and 770 cm-1. Which is a possible structure for the compound? Br Br Br II I III Br Br IV A) B) C) D) E) V I II III IV V Ans: D 513 Chapter 14 Topic: Spectroscopy 72. Which of the following substances, formula C8H9Br, might exhibit the following 1H NMR spectrum ? triplet, δ 2.8 triplet, δ 4.65 multiplet, δ 7.2 Br Br Br II I III Br Br IV A) B) C) D) E) V I II III IV V Ans: C 514 Chapter 14 Topic: Spectroscopy 73. Which of the following substances, formula C8H9Br, might exhibit the following 1H NMR spectrum ? triplet, δ 1.2 quartet, δ 2.45 multiplet, δ 7.4 Br Br Br II I III Br Br IV A) B) C) D) E) V I II III IV V Ans: A 515 Chapter 14 Topic: Spectroscopy 74. Which of the following substances, formula C8H9Br, might exhibit the following 1H NMR spectrum ? singlet, δ 2.45 singlet, δ 2.5 multiplet, δ 7.35 Br Br Br II I III Br Br V IV A) B) C) D) E) I II III IV V Ans: E Topic: Spectroscopy 75. Which of the following substances, C8H9Cl, would exhibit five signals in its 13C NMR spectrum? Cl Cl Cl I III II Cl Cl IV A) B) C) D) E) V I II III IV V Ans: C 516 Chapter 14 Topic: Spectroscopy 76. Which of the following substances, C9H10O, would exhibit seven signals in its 13C NMR spectrum? O O O I II III HO O V IV A) B) C) D) E) I II III IV V Ans: A Topic: Spectroscopy 77. For which of the following substances, C9H10O, would the aromatic multiplet, in its 1H NMR spectrum, consist of two doublets? O O O I II III HO O IV A) B) C) D) E) V I II III IV V Ans: A 517 Chapter 14 Topic: Spectroscopy 78. In the 1H NMR spectra of which of the following substances, C9H10O, would you expect to see two singlets in the range of δ 2.0-2.5 ppm? O O I O II III HO O IV A) B) C) D) E) V I and III I, II, and III IV V All of the above substances would exhibit two singlets δ 2.0-2.5 ppm in their 1H NMR spectra Ans: B SHORT ANSWER QUESTIONS Topic: General Concepts 79. A compound that reacts like an alkane, alkene, alkyne, or one of their derivatives, is called an _____________ compound, while one that reacts like benzene is called an _____________ compound. Ans: aliphatic, aromatic Topic: Nomenclature 80. When a benzene ring is used as a substituent, it is called a _________ group. Ans: phenyl Topic: General Concepts 81. The difference between the amount of heat actually released upon hydrogenation of benzene and that calculated on the basis of the Kekule structure is called the ____________________ of benzene. Ans: resonance energy 518 Chapter 14 Topic: General Concepts 82. Molecular orbitals of equal energy are referred to as _________ orbitals. Ans: degenerate Topic: Huckel’s rule 83. Hückel's Rule requires _________ π electrons for an aromatic compound. Ans: 4n+2 Topic: General Concepts 84. Monocyclic compounds with alternating single and double bonds are called __________. Ans: annulenes Topic: General Concepts 85. Cagelike molecules with the geometry of a truncated icosahedron are called ___________. Ans: fullerenes Topic: Aromaticity, Reactivity 86. Pyrrole is not particularly basic, because the lone pair on the nitrogen is ______________. Ans: part of the aromatic system Topic: General Concepts 87. Humans do not have the biochemical ability to synthesize the benzene ring. Therefore, two amino acids, _____________ and ___________, are essential to the human diet. Ans: tryptophan, phenylalanine Topic: Aromaticity, Reactivity 88. Benzene, while unusually unreactive, will react under certain conditions. However, when it does react, it does so by ___________ rather than by addition. Ans: substitution 519 Chapter 14 Topic: Nomenclature 89. Draw the structure corresponding to the following name: 2-bromo-5-nitrophenol OH Ans: Br O2 N Topic: Nomenclature 90. Draw the structure corresponding to the following name: 3-bromo 5-phenylacetophenone NH2 Ans: Br Topic: Nomenclature 91. Draw the structure corresponding to the following name: 2-hydroxy-4-(3methylcyclopentyl)benzoic acid HO Ans: HO2C Topic: Nomenclature 92. Draw the structure corresponding to the following name: 3-nitro-4-iodoanisole O Ans: O2N I Topic: Nomenclature 93. Give the IUPAC name for the following substance: OH O Ans: 2-methyl-4-(3-methylbutyl)benzoic acid Topic: Resonance 94. Draw all significant resonance structures for pyridine, C6H5N Ans: ..N N .. 520 Chapter 14 Topic: Resonance 95. Draw all significant resonance structures for azulene, C10H8 Ans: Topic: Aromaticity 96. Briefly explain why the aromatic hydrocarbon azulene, C10H8, possesses a significant dipole moment. Use diagrams as needed to illustrate/clarify your answer. Ans: Azulene has the bicyclic structure shown below. Since the “non-polar” resonance hybrid meets the Huckel rule for aromaticity, it accounts for the observed aromatic properties of azulene. However, closer scrutiny suggests that a shift in electron density, in which the 7-membered ring is electron deficient and the 5membered ring is electron-rich would be especially stable: each ring is now independently aromatic, an aromatic cycloheptatrienyl cation fused with an aromatic cyclopentadienyl anion. Thus, the most stable pi-electron distribution would suggest a polar structure for azulene, accounting for this substance having a significant dipole moment. non-polar polar Topic: Aromaticity, Molecular Orbital Theory 97. Use the “polygon-in-circle” method to draw an MO diagram showing the pi-electron distribution pattern in the cyclopentadienyl anion. How is this diagram useful in explaining the aromatic properties of this anion? Ans: The following MO diagram can be generated using the polygon-in-circle method. The six pi electrons of the cyclopentadienyl anion in the bonding molecular orbitals form a closed bonding shell, accounting for its aromatic properties. Antibonding MO Bonding MO 6 pi electrons "closed bonding shell" 521 Chapter 14 Topic: Aromaticity, Reactivity H .. 98. Explain briefly why cyclopentadiene readily reacts with strong bases. Ans: The acidity of a substance can be often be correlated with the stability of its conjugate base: substances that have exceptionally stable conjugate bases tend to be strong acids. The conjugate base of cyclopentadiene, formed during reaction with a base, is exceptionally stable, by virtue of being an aromatic anion (6 pi electrons, planar ring), thus accounting for the readiness with which cyclopentadiene reacts with bases. B:− H H Aromatic anion Topic: Resonance, Bond Lengths 99. Although all bond lengths in benzene are identical, that is not always true for all aromatic compounds. In naphthalene, for instance, the C1-C2 bond is shorter than the C2-C3 bond. Explain, using resonance theory. Ans: The major resonance structures for naphthalene are drawn below. The observed bond lengths reflect the contribution of each structure to the overall resonance hybrid: The C1-C2 bond: two double bonds (I and II), and one single bond (III) The C2-C3 bond: one double bond (III), and two single bonds (I and II) Overall: C1-C2 bond more double-bond-like, thus shorter. shorter 1 I 1 1 1 2 2 2 2 3 3 3 3 II III 522 IV longer Chapter 14 Topic: Aromaticity, Resonance Stabilization Energy 100. The heats of hydrogenation for cyclohexene and benzene are given below. Calculate the resonance stabilization energy of benzene. ΔHo = -120 kJ/mol C6H10 + H2 Æ C6H12 C6H6 + 3H2 Æ C6H12 ΔHo = -208 kJ/mol Ans: The resonance stabilization energy of benzene is the difference between the theoretical and observed ΔHo values. Hydrogenation of three double bonds should release 3 times the energy released when one double bond is hydrogenated. Thus, the theoretical ΔHo for benzene can be calculated as [3x (-120)] kJ/mol = -360 kJ/mol Therefore, Resonance stabilization energy of benzene = (-208) – (-360) kJ/mol = 152 kJ/mol 523 Chapter 14 Topic: Aromaticity, Reactivity 101. The Lewis structures of both pyridine and pyrrole have an electron pair on the nitrogen atom, suggesting that both substances might possess basic properties. However, only pyridine reacts readily with HCl to form pyridinium chloride, while pyrrole is rather unreactive. Explain clearly, using relevant diagrams to illustrate/clarify your answer. Ans: + HCl N+ − Cl H N .. 2 sp pyridinium chloride pyridinium chloride p .. N H + HCl H − N + Cl H X not aromatic pyrrole electron pair: part of aromatic pi sextet Both pyridine and pyrrole are known to exhibit aromatic properties; the nitrogen atom must therefore be sp2 hybridized in both cases. In the pyridine molecule, this places the electron pair in an sp2 hybrid orbital, and not involved in the aromatic π sextet needed for aromatic stability; the electron pair is thus “available” for reacting with HCl, forming pyridinium chloride, while preserving aromatic stability. By contrast, the electron pair in pyrrole must be placed in the p orbital, since all three sp2 orbitals are used in sigma bonds with neighboring atoms. This allows the electron pair to contribute to aromatic stability by becoming part of the aromatic sextet. Thus, the electron pair on nitrogen is not “available” for reacting with HCl, because doing so would destroy the aromaticity of the ring. 524 Chapter 14 Topic: Aromaticity, Bonding 102. Consider the oxygen atom in the molecules of furan and tetrahydrofuran. Bearing in mind that furan exhibits aromatic properties, compare the hybridization of oxygen in both species, explaining why it must be different, although at first glance, it may appear identical. .. .. O. O. . . Furan Ans: THF p .. O .. .. sp2 O 2 .. sp 3 sp 3 3 Furan: sp hybridized one electron pair in p orbital: Tetrahydrofuran: sp hybridized both electron pairs part of aromatic pi sextet in sp orbitals 3 Oxygen has 2 lone electron pairs in both species and, at first glance, it might appear that the hybridization patterns are identical. In THF, the oxygen atom is sp3 hybridized and both pairs can be placed in sp3 hybrid orbitals. In furan, there are two possibilities that must be considered: i) the oxygen may be sp3 hybridized, with both electron pairs sp3 hybrid orbitals, as in THF, or, ii) oxygen may be sp2 hybridized, with one electron pair in an sp3 hybrid orbital, the other in a p orbital. In the latter case, the electrons in the p orbital can then become part of an aromatic sextet, allowing the molecule to gain aromatic stability. Since furan is known to exhibit markedly aromatic properties, the oxygen must be sp2 hybridized. 525 Chapter 15 MULTIPLE CHOICE QUESTIONS Topic: Reaction Products 1. The major product(s), A, of the following reaction, Cl2, hν CH3CH2 CH3CH2 A 400 - 600 oC Cl CH3CH2 ClCH2CH2 CH3CH Cl Cl I II III IV would be: A) I B) II C) A mixture of I and II D) III E) IV Ans: E Topic: Reaction Products 2. What would be the major product(s) of the following reaction? CO2H HNO3 NO2 H2SO4, heat CO2H NO2 NO2 I A) B) C) D) E) Ans: CO2H NO2 NO2 ? CO2H O2N II O2N CO2H NO2 NO2 IV III I II III IV Equal amounts of II and IV C Page 526 Chapter 15 Topic: Reaction Products 3. The major product(s), C, of the following reaction, Cl Cl Cl SO3 H2SO4 C Cl Cl SO3H Cl I Cl SO3H HO3S II Cl III would be: A) I B) II C) III D) Equal amounts of I and II E) Equal amounts of I and III Ans: B 527 Chapter 15 Topic: Reaction Products 4. The major product(s), D, of the following reaction, O C CH2 Br Br2 D FeBr3 O O C CH2 C CH2 Br I II O O C CH2 C CH2 Br III IV would be: A) I B) II C) III D) IV E) Equal amounts of I and II Ans: D 528 Br Chapter 15 Topic: Reaction Products 5. What would be the product of the following reaction sequence? OH i) SOCl2 ? ii) C6H6, AlCl3 O iii) Zn(Hg), HCl, heat O O OH OH II I IV A) B) C) D) E) Ans: III V I II III IV V E 529 Chapter 15 Topic: Reaction Products 6. What would you expect to be the major product obtained from the following reaction? COOH Br2 SO3H COOH Br ? FeBr3 COOH COOH COOH Br SO3H SO3H Br SO3H SO3H Br I A) B) C) D) E) Ans: II III I II III IV Equal amounts of II and IV C IV Topic: Reaction Products 7. What would be the major product of the following reaction? Cl2 CH2CH2CH3 Cl CH2CH2CH3 400 oC ? CH2CH2CH3 Cl Cl I II CH2CHCH3 III CH2CH2CH2Cl Cl IV A) B) C) D) E) Ans: CHCH2CH3 V I II III IV V C 530 Chapter 15 Topic: Reaction Products 8. What would you expect to be the major product obtained from the following reaction? NO2 Br2 NO2 ? FeBr3 SO3H NO2 NO2 NO2 Br Br SO3H SO3H Br SO3H SO3H Br I A) B) C) D) E) Ans: II III I II III IV Equal amounts of II and IV C IV Topic: Reaction Products 9. What would you expect to be the major product obtained from the following reaction? O HNO3 H2SO4, heat HN O O2N HN ? O NO2 O HN HN II III O2N I O O HN HN IV A) B) C) D) E) Ans: NO2 V I II III IV V E 531 NO2 Chapter 15 Topic: Reaction Products 10. What would be the major product(s) of the following reaction? O H2SO4 ? NO2 O O O O HO3S SO3H NO2 I A) B) C) D) E) Ans: NO2 SO3H II NO2 NO2 HO3S IV III I II III Equal amounts of IV Equal amounts of II and IV C Topic: Reaction Products 11. What would you expect to be the major product obtained from the mononitration of mdichlorobenzene? Cl Cl Cl NO2 Cl I A) B) C) D) E) Ans: Cl NO2 O2N Cl II III I II III Equal amounts of I and II Equal amounts of I, II and III B 532 Chapter 15 Topic: Reaction Products 12. What would you expect to be the major product obtained from the following reaction? HO O HNO3 H2SO4 , heat SO3H HO HO O O HO HO O I A) B) C) D) E) Ans: O O2N NO2 SO3H ? SO3H O2N NO2 II SO3H SO3H IV III I II III IV Equal amounts of I and II C 533 Chapter 15 Topic: Reaction Products 13. What product would result from the following series of reactions, i) AlCl3 Cl ii) N-Bromosuccinimide, peroxides ? + iii) CH3ONa, CH3OH, heat iv) MMPP v) CH3MgBr vi) NH4Cl Br HO HO I II HO IV A) B) C) D) E) Ans: III HO V I II III IV V D 534 Chapter 15 Topic: Reaction Products 14. The major product(s), D, of the following reaction HNO3 O D H2SO4 O O2N O I NO2 II O NO2 O NO2 III IV would be: A) I B) II C) III D) IV E) Equal amounts of I and II Ans: D 535 Chapter 15 Topic: Reaction Products 15. What would be the major product of the following reaction? NBS, ROOR ? light Br Br Br I II III Br Br IV A) B) C) D) E) Ans: V I II III IV V C Topic: Reaction Products 16. Which would be the major product(s) of the following reaction? HO O HNO3 H2SO4 HO HO O ? O HO O NO2 NO2 I A) B) C) D) E) Ans: HO3S II III I II III I and II in roughly equal amounts I and III in roughly equal amounts A 536 Chapter 15 Topic: Reaction Products 17. Which would be the product, X, of the following reaction sequence? O i) SOCl2 ? OH ii) benzene, AlCl3 iii) Zn(Hg), HCl SO2 CO2 CH2 I II III O IV A) B) C) D) E) Ans: V I II III IV V C 537 Chapter 15 Topic: Reaction Products 18. Toluene is subjected to the action of the following reagents in the order given: (1) KMnO4,OH-, heat; then H3O+ (2) HNO3, H2SO4 (3) Br2, FeBr3 What is the final product of this sequence? CO2H Br CO2H NO2 CO2H NO2 Br I NO2 Br II III Br CH3 Br A) B) C) D) E) Ans: NO2 NO2 CO2H IV V I II III IV V A Topic: Reaction Products 19. When toluene is reacted in turn with 1) Cl2 (large excess), heat, and light and 2) Br2,FeBr3, the chief product is: Br CCl3 CCl3 CCl3 Br Br Cl I A) B) C) D) E) Ans: Br II III IV I II III IV A mixture of III and IV B 538 Chapter 15 Topic: Reaction Products 20. The reaction of benzene with (CH3)3CCH2Cl in the presence of anhydrous aluminum chloride produces principally which of these? II I IV A) B) C) D) E) Ans: III V I II III IV V E Topic: Reaction Products 21. What might be predicted to happen when the following substance undergoes FriedelCrafts acylation? O2N A) B) C) D) E) Ans: CH2 A B Substitution occurs in ring B, p- to the methylene group Substitution occurs in ring A, o- to the nitro group Substitution occurs in ring A, o- to the methylene group Substitution occurs in ring B, m- to the methylene group None of the above. No reaction will occur. A 539 Chapter 15 Topic: Nomenclature, Reaction Products 22. A mixture of chlorobenzene (1 mol) and acetanilide (1mol) is allowed to react with Br2 (0.5 mol) in the presence of trace amounts of FeBr3. What is the principal product of the competing reactions? A) 1-bromo-4-chlorobenzene B) 1-bromo-2-chlorobenzene C) 1-bromo-3-chlorobenzene D) 4-bromoacetanilide E) 3-bromoacetanilide Ans: D Topic: Nomenclature, Reaction Products 23. What is the chief product of the Friedel-Crafts alkylation of benzene with 1-butene and AlCl3? A) butylbenzene B) 2-phenylbutane C) 2-methyl-1-phenylpropane D) t-butylbenzene E) 2,2-diphenylbutane Ans: B 540 Chapter 15 Topic: Reaction Products 24. Which of the following reactions would give the product(s) indicated in substantial amounts (i.e., in greater than 50% yield)? NH2 NH2 + CH3Cl I AlCl3 NH2 and CH3 CH3 NH2 II NH2 + CH3Cl AlCl3 CH3 III A) B) C) D) E) Ans: + CH3CH2CH2Cl AlCl3 CH2CH2CH3 I II III All of these None of these E Topic: Reagents 25. Which reagent(s) would you use to carry out the following transformation? toluene ⎯⎯⎯→ benzoic acid A) Br2, heat, and light B) Cl2, FeCl3 C) KMnO4, OH-, heat (then H3O+) D) HNO3/H2SO4 E) SO3/H2SO4 Ans: C 541 Chapter 15 Topic: Reagents 26. Which reagent(s) would you use to carry out the following transformation? ethylbenzene ⎯⎯⎯→ 1-chloro-1-phenylethane A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) HCl, O2 Ans: A Topic: Reagents 27. Which reagent(s) would you use to carry out the following transformation? isopropylbenzene ⎯⎯⎯→ 2- and 4-chloro-1-isopropylbenzene A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) HCl, peroxides Ans: B Topic: Reagents 28. Which reagent would you use to carry out the following transformation? tert-butylbenzene ⎯⎯⎯→ p-tert-butylbenzenesulfonic acid + o-tert-butylbenzenesulfonic acid A) HNO3/H2SO4 B) tert-C4H9Cl/AlCl3 C) H2SO3/peroxides D) SO3/H2SO4 E) SO2/H2SO3 Ans: D Topic: Reagents 29. Which reagent(s) would you use to carry out the following transformation? ethylbenzene ⎯⎯⎯⎯→ benzoic acid A) Cl2, light, and heat B) Cl2, FeCl3 C) KMnO4, OH-, heat (then H3O+) D) HNO3/H2SO4 E) SO3/H2SO4 Ans: C 542 Chapter 15 Topic: Reagents 30. Which reagent(s) would you use to carry out the following transformation? ethylbenzene ⎯⎯→ 2- and 4-chloro-1-ethylbenzene A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) None of these Ans: B Topic: Reagents 31. Which reagent(s) would you use to carry out the following transformation? t-butylbenzene ⎯⎯⎯→ p-chloro substitution product A) Cl2, light, and heat B) Cl2, FeCl3 C) SOCl2 D) C2H5Cl, AlCl3 E) HCl, peroxide Ans: B Topic: Reagents 32. Which reagent(s) would you use to carry out the following transformation? toluene ⎯⎯⎯→ benzyl bromide A) Br2, FeBr3 B) N-Bromosuccinimide, ROOR, hν C) HBr D) Br2/CCl4 E) NaBr, H2SO4 Ans: B Topic: Reagents 33. Which reagent(s) would you use to synthesize 2- and 4-bromo-1-cyclopentylbenzene from cyclopentylbenzene? A) N-Bromosuccinimide (NBS), CCl4, light B) PBr3 C) Br2, FeBr3 D) CH3CH2Br, AlBr3 E) HBr, ROOR Ans: C 543 Chapter 15 Topic: Reagents 34. The compound 4-bromo-1-propylbenzene is best made from benzene by the application of these reagents in the order shown: A) (1) Br2,Fe (2) CH3CH2CH2Cl, AlCl3 B) (1) CH3CH2CH2Cl, AlCl3 (2) Br2,Fe C) 1) CH3CH2CCl , AlCl3 2) Br2, Fe 3) Zn(Hg), HCl O D) 1) CH3CH2CCl , AlCl3 2) Zn(Hg), HCl 3) Br2, Fe O E) (1) (CH3)2CHCl, AlCl3 (2) Br2,Fe Ans: D Topic: Functional Group Tests 35. Which reagent would you use as the basis for a simple chemical test that would distinguish between toluene and vinylbenzene (C6H5CH=CH2)? A) NaOH/H2O B) Br2/CCl4 C) NaBH4 D) HCl/H2O E) NaI in acetone Ans: B Topic: Nomenclature, Functional Group Tests 36. Which reagent or test could you use to distinguish between phenylacetylene and vinylbenzene? A) NaOH/H2O B) Br2/CCl4 C) IR Spectroscopy D) CrO3/H2SO4 E) Concd. H2SO4 Ans: C 544 Chapter 15 Topic: Nomenclature, Synthesis 37. Which of the following would be the best synthesis of 1,4-dimethyl-2-nitrobenzene? A) HNO3 2 CH3Cl Benzene product 2 AlCl3 H2SO4 HNO3 CH3Cl B) Toluene product AlCl3 H2SO4 HNO C) 3 p-Xylene H2SO4 CH3Cl D) m-Nitrotoluene AlCl3 E) All of these are equally good. Ans: C Topic: Synthesis 38. Starting with benzene, the best method for preparing p-nitrobenzoic acid is: A) HNO3/H2SO4; then CH3Cl/AlCl3; then separation of isomers; then KMnO4/ OH/heat, followed by H3O+. B) CH3Cl/AlCl3; then HNO3/H2SO4; then separation of isomers; then KMnO4/ OH/heat, followed by H3O+. C) CH3Cl/AlCl3; then KMnO4/-OH/heat, followed by H3O+; then HNO3/H2SO4. D) HNO3/H2SO4; then KMnO4/-OH/heat, followed by H3O+; then CH3Cl/AlCl3. E) HNO3/H2SO4; then CO2, followed by H3O+. Ans: B 545 Chapter 15 Topic: Synthesis 39. A good synthesis of O (CH3)3C CCH3 would be: A) Benzene O CH3CCl (CH3)3CCl AlCl3 AlCl3 O B) Benzene (CH3)3CCl CH3CCl AlCl3 AlCl3 O C) Benzene CH3CCl AlCl3 D) More than one of these E) None of these Ans: B (CH3)2C CH2 HF Topic: Synthesis 40. Which would be a good synthesis of m-nitrobenzoic acid? A) HNO3/H2SO4 CH3Cl 1. KMnO4, NaOH, heat Benzene heat AlCl3 2. H3O+ B) Toluene C) Toluene HNO3/H2SO4 1. KMnO4, NaOH, heat 2. H3O+ 1. KMnO4, NaOH, heat HNO3/H2SO4 heat 2. H3O+ D) More than one of the above E) None of the above Ans: C heat 546 Chapter 15 Topic: Synthesis 41. Benzoic acid can be prepared by the oxidation of all of the following compounds except this one: A) C6H5CH=CH2 B) C6H5C≡CH C) C6H5COCH3 D) C6H5CH2CH2CH3 E) C6H5C(CH3)3 Ans: E Topic: Synthesis 42. Which of the following reactions would yield isopropylbenzene as the major product? CH3CH CH2 A) Benzene H2SO4 CH B) 3CHCH3 Benzene H2SO4 CH3CHCH3 C) Benzene D) OH Benzene Cl AlCl3 CH3CH2CH2Cl AlCl3 E) All of these Ans: E Topic: Synthesis 43. Which of the following reactions could be used to synthesize tert-butylbenzene? H2SO4 A) C6H6 + CH2=C(CH3)2 H2SO4 B) C6H6 + (CH3)3COH AlCl3 C) C6H6 + (CH3)3CCl D) All of the above E) None of the above Ans: D 547 Chapter 15 Topic: Synthesis 44. Which of these is a satisfactory synthesis of 1-chloro-2-phenylethane? A) C6H5CH2CH3 + Cl2, Fe ⎯⎯→ B) C6H5CH2CH3 + Cl2, 400°C ⎯⎯→ C) C6H5CH2CH2OH + SOCl2 ⎯⎯→ D) C6H5CH=CH2 + HCl, peroxide ⎯⎯→ E) C6H6 + CH3CH2Cl, AlCl3 ⎯⎯→ Ans: C Topic: Synthesis 45. Which of the following reactions would produce isopropylbenzene? Cl A) Benzene AlCl3 B) Benzene HF OH C) Benzene H2SO4 Br D) Benzene AlCl3 E) All of these Ans: E 548 Chapter 15 Topic: Synthesis 46. How might the following synthesis be carried out: CH2CH3 Benzene A) B) C6H6 several steps CH3CH2Cl C6H6 AlCl3 Cl2 FeCl3 ? Cl Cl2 FeCl3 CH3CH2Cl AlCl3 product product O C) C6H6 CH3CCl Cl2 Zn(Hg) AlCl3 FeCl3 HCl Zn(Hg) Cl2 product O D) C6H6 CH3CCl HCl AlCl3 E) None of these syntheses is satisfactory. Ans: C FeCl3 product Topic: Synthesis 47. Which is the best sequence of reactions for the preparation of p-bromostyrene from ethylbenzene? A) NBS, hν Br2 KOH product ethylbenzene Fe CCl4 CH3CH2OH B) NBS, hν Br2 KOH product ethylbenzene Fe CCl4 CH3CH2OH C) NBS, hν KOH Br2 product ethylbenzene Fe CCl4 CH3CH2OH ZnO Br2 D) product ethylbenzene Fe 630 oC E) None of these syntheses is satisfactory. Ans: B 549 Chapter 15 Topic: Synthesis 48. Which is the best sequence of reactions for the following transformation? O NO2 A) B) C) D) E) Ans: i) HNO3, H2SO4; ii) CH3MgBr, Et2O; iii) H3O+, heat i) CH3MgBr, Et2O; ii) H3O+, heat; iii) HNO3, H2SO4 i) HNO3, H2SO4; ii) NaBH4, H2O; iii) H3O+, heat i) HNO3, H2SO4; ii) NaBH4, H2O; iii) H3O+, heat None of these syntheses is satisfactory. A Topic: Synthesis 49. Which is the best sequence of reactions for the following transformation? OH O OCH3 NO2 A) B) C) D) E) Ans: i) HNO3, H2SO4; ii) 2EtMgBr, Et2O; iii) NH4Cl i) 2EtMgBr, Et2O; ii) H3O+; iii) HNO3, H2SO4 i) HNO3, H2SO4; ii) NaBH4, H2O; iii) 2EtMgBr, Et2O i) LAH; ii) 2EtLi, Et2O; iii) HNO3, H2SO4, heat None of these syntheses is satisfactory. A Topic: Synthesis 50. Which is the best sequence of reactions for the following transformation? O OH NO2 A) B) C) D) E) Ans: i) SOCl2; ii) C6H6, AlCl3; iii) Zn(Hg),HCl; iv) HNO3, H2SO4 i) SOCl2; ii) HNO3, H2SO4; iii) C6H6, AlCl3; iv) H2, Ni i) HNO3, H2SO4; ii) SOCl2; iii) C6H6, AlCl3; iv) Zn(Hg),HCl i) PBr3; ii) HNO3, H2SO4; iii) C6H6, AlCl3; iv) NaBH4, H2O two of these syntheses are satisfactory. C 550 Chapter 15 Topic: Relative Reactivities 51. Which of the following compounds would be most reactive toward electrophilic substitution? OH CH3 I II A) B) C) D) E) Ans: Br III CHO NO2 IV V I II III IV V A Topic: Relative Reactivities 52. Which of the following compounds would be most reactive to ring bromination? CH3 I A) B) C) D) E) Ans: NO2 II CF3 III Cl NH2 IV V I II III IV V E Topic: Relative Reactivities 53. Which of the following compounds would you expect to be most reactive toward ring nitration? A) Benzene B) Toluene C) m-Xylene D) p-Xylene E) Benzoic acid Ans: C 551 Chapter 15 Topic: Relative Reactivities 54. Which of the following compounds would be least reactive toward electrophilic substitution? O O NO2 NH NO2 I A) B) C) D) E) Ans: II IV III V I II III IV V B Topic: Relative Reactivities 55. Which of the following compounds would be most reactive toward ring nitration? O O O I A) B) C) D) E) Ans: II CF3 III I II III IV V D 552 OH NH IV V Chapter 15 Topic: Relative Reactivities 56. Which of the compounds listed below would you expect to give the greatest amount of meta-product when subjected to ring bromination? HO OH O NH2 II I A) B) C) D) E) Ans: III OCH3 CH3 IV V I II III IV V B Topic: Relative Reactivities 57. Which of the following compounds would be most reactive toward ring bromination? O HO O O NH2 OCH3 O O O II I A) B) C) D) E) Ans: IV III I II III IV V C 553 V Chapter 15 Topic: Relative Reactivities 58. Which of the compounds listed below would you expect to give the greatest amount of meta-product when subjected to ring nitration? O I A) B) C) D) E) Ans: II O NH III OCH3 CH3 IV V I II III IV V B Topic: Mechanisms and Intermediates 59. Which of the following structures contribute(s) to the resonance hybrid of the intermediate formed when bromobenzene undergoes para-chlorination? .. .. .. .. : Br : : Br + : Br : : Br : + + + H Cl H Cl H Cl H Cl I II III IV A) B) C) D) E) Ans: I II III IV All of the above E 554 Chapter 15 Topic: Mechanisms and Intermediates 60. Which of the following contributors to the resonance stabilized hybrid formed when aniline undergoes para-chlorination would be exceptionally stable? +NH2 : NH2 : NH2 : NH2 + + + H Cl H Cl H Cl H Cl I II III IV A) B) C) D) E) Ans: I II III IV None of these B Topic: Mechanisms and Intermediates 61. Consider the structures given below. Which of them would be a relatively stable contributor to the hybrid formed when toluene undergoes para bromination? CH3 CH3 CH3 CH3 CH3 + + H Br Br II I A) B) C) D) E) Ans: + + H Br H Br III IV I II III IV V C 555 Br+ IV Chapter 15 Topic: Mechanisms and Intermediates 62. Which of the following structures does not contribute to the resonance hybrid of the intermediate formed when nitrobenzene undergoes meta-chlorination? .. .. .. .. .. .. :O : O: : O : O: : O : O: N N + I A) B) C) D) E) Ans: H Cl + N + H Cl II H Cl III I II III None of these contribute All of these contribute. E Topic: Mechanisms and Intermediates 63. Which of these is the rate-determining step in the nitration of benzene? A) Protonation of nitric acid by sulfuric acid B) Protonation of sulfuric acid by nitric acid C) Loss of a water molecule by the protonated species to produce the nitronium ion D) Addition of nitronium to benzene to produce the arenium ion E) Loss of a proton by arenium ion to form nitrobenzene Ans: D Topic: Directing Effects 64. The ortho/para product ratio is expected to be the smallest for the bromination of which of these? A) Toluene B) Isopropylbenzene C) Butylbenzene D) sec-Butylbenzene E) tert-Butylbenzene Ans: E 556 Chapter 15 Topic: Directing Effects 65. Which of the following is not a meta-directing substituent when present on the benzene ring? A) -NHCOCH3 B) -NO2 C) -N(CH3)3+ D) -C≡N E) -CO2H Ans: A Topic: Directing Effects 66. Each of the five disubstituted benzenes shown below is nitrated. In which of these cases does the arrow not indicate the chief position of nitration. Cl COOH Cl NHCOCH3 O CCH3 Cl NO2 OH A) B) C) D) E) Ans: I I II III IV V C II III 557 CH3 CH2CH3 IV V Chapter 15 Topic: Directing Effects 67. Which of the following compounds would yield the greatest amount of meta product when subjected to ring nitration? HO O HO O HO O I A) B) C) D) E) Ans: O O HO OH II IV III V I II III IV V A Topic: Directing Effects 68. Which of the following is not an ortho-para director in electrophilic aromatic substitution? A) -CF3 B) -OCH3 C) -CH3 D) -F E) -NH2 Ans: A Topic: Directing Effects 69. Which of these compounds gives essentially a single product on electrophilic substitution of a third group? A) p-chlorotoluene B) m-ethylanisole C) 1-bromo-2-chlorobenzene D) m-xylene E) 3-hydroxybenzoic acid Ans: D 558 Chapter 15 Topic: Directing Effects 70. What is a feature found in all ortho-para directing groups? A) An oxygen atom is directly attached to the aromatic ring. B) The atom attached to the aromatic ring possesses an unshared pair of electrons. C) The group has the ability to delocalize the positive charge of the arenium ion. D) The atom directly attached to the aromatic ring is more electronegative than carbon. E) The group contains a multiple bond. Ans: C Topic: Directing Effects 71. Which is the best prediction of the site(s) of substitution when 3-methylphenol is nitrated? A) C-2 B) C-4 C) C-5 D) C-6 E) C-4 and C-6 Ans: E Topic: Directing Effects 72. (Trifluoromethyl)benzene, C6H5CF3, will A) nitrate rapidly in the ortho-para positions. B) nitrate slowly in the ortho-para positions. C) nitrate rapidly in the meta position. D) nitrate slowly in the meta position. E) fail to nitrate under any conditions. Ans: D Topic: Directing Effects 73. What feature is common to all meta-directing groups? A) The atom directly attached to the ring has a full or well-developed partial positive charge. B) The atom directly attached to the ring is doubly bonded to oxygen. C) One or more halogen atoms are present in the group. D) One or more oxygen atoms are present in the group. E) The group is attached to the ring through a carbon atom. Ans: A 559 Chapter 15 Topic: Directing Effects 74. Arrange the following compounds in order of decreasing reactivity in electrophilic substitution: O I A) B) C) D) E) Ans: O II V > II > I > III > IV II > V > III > I > IV IV > I > III > V > II III > II > I > IV > V IV > V > II > I > III B Br NO2 IV III V Topic: Other EAS Considerations 75. Which of these liquids would be unsuitable as an inert solvent for a Friedel-Crafts reaction? A) Chlorobenzene B) Nitrobenzene C) Acetophenone D) (Trifluoromethyl)benzene E) All could be used. Ans: A Topic: Other EAS Considerations 76. Undesired polysubstitution of an aromatic nucleus is most likely to be encountered in the case of: A) Friedel-Crafts alkylation B) Friedel-Crafts acylation C) Nitration D) Sulfonation E) Chlorination Ans: A 560 Chapter 15 Topic: Other EAS Considerations 77. This molecule cannot participate as a reactant in a Friedel-Crafts reaction. A) Benzene B) Chlorobenzene C) Nitrobenzene D) Toluene E) tert-Butylbenzene Ans: C Topic: Other EAS Considerations 78. Which one of these molecules can be a reactant in a Friedel-Crafts reaction? A) Aniline B) Nitrobenzene C) Chloroethene D) Bromobenzene E) p-Bromonitrobenzene Ans: D Topic: Other EAS Considerations 79. This substituent deactivates the benzene ring towards electrophilic substitution but directs the incoming group chiefly to the ortho and para positions. A) -OCH2CH3 B) -NO2 C) -F D) -CF3 E) -NHCOCH3 Ans: C Topic: Other EAS Considerations 80. In electrophilic aromatic substitution, the attacking species (the electrophile) necessarily is a: A) Neutral species. B) Positively charged species. C) Lewis acid. D) Proton. E) Carbocation. Ans: C 561 Chapter 15 Topic: Other EAS Considerations 81. The electrophilic bromination or chlorination of benzene requires, in addition to the halogen: A) Hydroxide ion. B) A Lewis base. C) A Lewis acid. D) Peroxide. E) Ultraviolet light. Ans: C Topic: Non-EAS Reactions 82. What is the Birch reduction product of the following reaction? Na, NH3(l) EtOH II I A) B) C) D) E) Ans: ? IV III I II III IV V D Topic: Non-EAS Reactions 83. SN1 solvolysis of C6H5CH=CHCH2Cl in water produces: A) C6H5CH2C(OH)=CH2 B) C6H5CH=CHCH2OH C) C6H5CHOHCH=CH2 D) A mixture of B) and C) E) A mixture of A), B) and C) Ans: D 562 V Chapter 15 Topic: Non-EAS Reactions 84. Which compound is capable of undergoing both SN1 and SN2 reactions in ordinary nonacidic solvents? Br Br Br Br Br I A) B) C) D) E) Ans: II III IV V I II III IV V D Topic: Non-EAS Reactions 85. Which alkyl halide can undergo both SN1 and SN2 reactions in nonacidic solvents? A) CH3Br B) CH3CH2CH2Br CH2 CHCHCH3 C) Br D) E) C6H5CH2CH2CH2Br CH3 C6H5CCH2Br CH3 Ans: C Topic: Non-EAS Relative Rates and Intermediates 86. The rate of solvolysis in ethanol is least for which of these compounds? A) C6H5CH2Cl C6H5C(CH3)2 B) Cl C) D) (C6H5)2CHCl C6H5CHCl CH3 E) (C6H5)3CCl Ans: A 563 Chapter 15 Topic: Non-EAS Relative Rates and Intermediates 87. Which of the following structures would not be a contributor to the resonance hybrid of the benzyl cation? CH3 H H + I A) B) C) D) E) Ans: CH3 +CH2 CH2 + CH3 + + II IV III IV I II III IV V A Topic: Non-EAS Relative Rates and Intermediates 88. Which of these species is/are proposed as intermediate(s) in the mechanism for the Birch reduction? A) Radical B) Carbanion C) Radical anion D) Both A) and B) E) All of A), B) and C) Ans: E 564 Chapter 15 Topic: Non-EAS Relative Rates and Intermediates 89. Which of the following carbocations would be most stable? CH3 A) C6H5CH2CH2CHCH2 B) C) CH2 C6H5CH2CH2CHCH3 CH3 C6H5CH2CH2CCH3 CH3 D) E) C6H5CH2CHCHCH3 CH3 C6H5CHCH2CHCH3 Ans: E Topic: Non-EAS Relative Rates and Intermediates 90. Which alkyl halide would be most reactive in an SN2 reaction? A) C6H5CH2CH2CH2Br C6H5CHCH2Br B) C) CH3 C6H5CH2CHCH3 Br CH3 D) C6H5CCH2Br CH3 Br E) C6H5CCH3 CH3 Ans: A 565 Chapter 15 Topic: Non-EAS Relative Rates and Intermediates 91. Which alkyl halide would be most reactive in an SN1 reaction? A) C6H5CH2CH2CH2Br C6H5CH2CHCH3 B) Br CH3 C) C6H5CH2CBr CH3 Br D) C6H5CCH3 CH3 CH3 E) C6H5CCH2Br CH3 Ans: D SHORT ANSWER QUESTIONS Topic: General 92. Aromatic hydrocarbons are generally known as ____________. Ans: arenes Topic: General Reactivity 93. Benzene is susceptible to electrophilic attack primarily because of its _____________. Ans: exposed π system Topic: General Reactivity 94. Although benzene is susceptible to electrophilic attack, its special stability causes it to undergo ______________ rather than ____________ reactions. Ans: substitution; addition 566 Chapter 15 Topic: EAS Mechanism 95. In general, there are three steps to an electrophilic aromatic substitution reaction. These are: a) formation of an _____________; b) reaction with an aromatic ring to form an ___________; and c) loss of a _________ to reform the aromatic system. Ans: electrophile; arenium ion; proton Topic: General Reactivity 96. Aryl and vinyl halides cannot be used in the Friedel-Crafts alkylation because they do not __________. Ans: form carbocations readily Topic: General EAS Reactivity 97. Substituent groups affect both _____________ and _______________ in electrophilic aromatic substitution reactions. Ans: reactivity; orientation Topic: General EAS Reactivity 98. Electron-donating groups increase the electron density on the aromatic ring, causing it to be more reactive than benzene itself towards EAS. These types of groups are called _____________ groups. Ans: activating Topic: General EAS Reactivity 99. Electron-withdrawing groups decrease the electron density on the aromatic ring, causing it to be less reactive than benzene itself towards EAS. These types of groups are called _____________ groups. Ans: deactivating Topic: General EAS Reactivity 100. With the exception of halogens, activating groups are ____________ directors and deactivating groups are _________ directors. Ans: ortho/para; meta 567 Chapter 15 Topic: General EAS Reactivity 101. When two different groups are present on a benzene ring, the ____________ generally determines the outcome of an EAS reaction. Ans: more powerful activating group Topic: EAS/non-EAS Reactivity 102. When toluene reacts with Cl2, the identity of the major product(s) obtained depends on whether the reaction is carried out in the presence of catalytic amounts of FeCl3, or without catalyst, at high temp. Explain clearly. Ans: Reaction with Cl2/FeCl3 results in electrophilic aromatic substitution at the o- and p- positions, since the methyl group in toluene is an activating, o-,p- director. In contrast, when the reaction is carried out without catalyst, at high temperature, the methyl group undergoes free-radical halogenation via the benzyl radical intermediate. Cl2 FeCl3 Cl + Cl Cl Cl2 heat 568 Chapter 15 Topic: General EAS Reactivity 103. When the following substance is treated with Br2/FeBr3, the major product is obtained in good yield, and only very small amounts of minor products are found. What is this major product and why are the minor products not formed to any significant degree? Explain clearly. O Br2 FeBr3 HN O ? Ans: The major products are produced by brominating Ring B. Ring B is more electron-rich due to the electron-donation of both the nitrogen and methyl groups attached versus the two electron-withdrawing carbonyl groups attached to Ring A, which make it inherently electron-poor. Therefore, bromination mainly occurs on the more electron-rich benzene ring affording a mixture of the following two compounds. Due to steric effects, bromination ortho to both the nitrogen and methyl group would lead to a minor product. Also, because Ring A is electronpoor, bromination of this ring would also lead to minor products. Ring Ring A A O O HN O Br + Ring B major products HN O Br Ring B Topic: Synthetic Strategy 104. Suggest a reasonable synthetic strategy for the synthesis of 3,5-dinitrobenzyl alcohol from benzaldehyde. NO2 NO2 Ans: HNO3 (excess) NaBH4 O H2SO4 O H2O OH O2 N O2 N heat benzaldehyde 3,5-dinitrobenzyl alcohol Topic: Synthetic Strategy 105. Suggest a reasonable synthetic strategy for the synthesis of 4-methyl-1-phenyl-1pentanol from 4-methylpentanoyl chloride, (CH3)2CHCH2CH2COCl O OH Ans: NaBH4 Cl H2O AlCl3 O 4-methylpentanoyl chloride 4-methyl-1-phenyl-1-pentanol 569 Chapter 15 Topic: Synthetic Strategy 106. Suggest a reasonable synthetic strategy for the synthesis of 6-methyl-3-phenyl-3heptanol from 4-methylpentanoyl chloride, (CH3)2CHCH2CH2COCl Ans: O OH O i) C2H5MgBr ii) NH4Cl Cl AlCl3 4-methylpentanoyl chloride 6-methyl-3-phenyl-3-heptanol Topic: Mechanism, Carbocation Stability 107. Acid-catalyzed hydration of 1-phenyl-1-pentene gives 1-phenyl-1-pentanol almost exclusively; the other possible hydration product, 1-phenyl-2-pentanol, is not detected at all. Explain clearly. Ans: Acid catalyzed hydration of an alkene occurs through a carbocation intermediate. Although 1-phenyl-1-pentene is symmetrically substituted at the C=C, the relative stabilities of the two possible carbocation intermediates is significantly different: although both are secondary carbocations, one is also benzylic and thus stabilized by resonance. The observation that 1-phenyl-1-pentene gives 1-phenyl-1pentanol, almost exclusively, is in accordance with the general trend that acid catalyzed hydration chiefly tends to afford products formed via the most stable intermediate carbocation. H3O+ H2O H + H + + 2o, benzylic: stabilized by resonance,formed 2o, but not benzylic: almost exclusively appreciable degree less stable, not formed to any OH H chief product 570 H + OH not detected Chapter 15 Topic: Spectroscopic Analysis 108. How might 1H NMR spectroscopy be useful in distinguishing between the following two substances? O O O O A B Ans: The chemical shift of the methyl protons is likely to be markedly different in the two substances. In A, the signal may be expected at about 3.5-4.0 ppm (attachment to O), while in B, it is likely to show up at about 2.0 ppm (attachment to >C=O). 571 Chapter 16 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. What is the correct IUPAC name for the following compound? O A) B) C) D) E) Ans: 2-Methyl-5-heptanone 7-Methyl-4-octanone 6-Isopropyl-4-octanone Isobutyl propyl ketone 1,1-Dimethyl-4-heptanone B Topic: Nomenclature 2. What is the correct IUPAC name for the following compound? O A) B) C) D) E) Ans: 5,5-Dimethyl-2-heptanone 5-Ethyl-5,5-dimethyl-Methyl-2-octanone 5-Ethyl-5-methyl- 2-hexanone 5,5-Dimethyl-2-octanone 3,3-Dimethyl-6-heptanone A Topic: Nomenclature 3. What is the correct IUPAC name for the following compound? O A) B) C) D) E) Ans: 1,1,2-Trimethyl-1,3-hexenone 1,2-Dimethyl-1,3-hexenone 2,3-Dimethyl-1,3-heptenone 2,3-Dimethyl-2-hepten-4-one 5,6-Dimethyl-5-hepten-4-one C 572 Chapter 16 Topic: Nomenclature O 4. A correct name for C6H5CH2CH2CH is? A) 3-Benzylpropanone B) 3-Phenylpropanal C) 3-Benzylpropanal D) Nonanone E) Nonanal Ans: B Topic: Nomenclature 5. A correct name for the following compound would be which of those below? O H A) B) C) D) E) Ans: 2,5-Dimethyl-6-hexanal 2,5-Dimethylhexanal 2-Aldehydoisohexane 3,5-Dimethylheptanone 1-Hydro-2,5-dimethyl-1-hexanone B Topic: Nomenclature O 6. CH3 CH CH2 OH What is the IUPAC name for A) 4-Oxo-5-phenyl-2-hexanol B) 5-Hydroxy-2-phenyl-3-hexanone C) 2-Hydroxy-5-phenyl-4-hexanone D) 2-Hydroxypropyl-1-phenylethyl ketone E) 5-Hydroxy-3-keto-2-phenylhexane Ans: B 573 C CH C 6H 5 CH3 ? Chapter 16 Topic: Nomenclature 7. Which is the proper name for the structure shown? CHO Cl CH3 A) B) C) D) E) Ans: 2-Chloro-5-aldehydotoluene 6-Chloro-3-aldehydotoluene 2-Methyl-4-aldehydochlorobenzene 4-Chloro-3-methylbenzaldehyde 4-Methyl-5-chloro-2-benzaldehyde D Topic: Nomenclature 8. Which is the proper name for the structure shown? O2 N O NO2 A) B) C) D) E) Ans: 3-Methyl-5-(1,4-dinitrobenzyl)-1-pentanal 3-Methyl-1-(2,5-dinitrophenyl)-5-pentanal 3-Methyl-5-(2,5-dinitrophenyl)pentanal 3-Methyl-5-(2,5-dinitrophenyl)pentanaldehyde 3-Methyl-5-(2,5-dinitrophenyl)pentaldehyde C Topic: Nomenclature 9. Which is the proper name for the structure shown? O Cl A) B) C) D) E) Ans: 3,5-Dimethyl-5-(4-chlorobenzyl)-1-pentanal 3-Methyl-5-(4-chlorophenyl)hexanol 3,5-Dimethyl-5-(4-chlorophenyl)-1-pentanaldehyde 3-Methyl-5-(4-chlorophenyl)-hexanaldehyde 3-Methyl-5-(4-chlorophenyl)hexanal E 574 Chapter 16 Topic: Nomenclature 10. Which is the proper name for the structure shown below? Br O A) B) C) D) E) Ans: 7-Bromo-1,4-octynal 7-Bromo-1,4-octynone 2-Bromo-5,7-octynal 7-Bromo-7-methyl-1-heptyne-3-ketone 7-Bromo-1-octyn-4-one E Topic: Nomenclature 11. Which is the IUPAC name for the structure shown below? Br H O A) B) C) D) E) Ans: (R)-5-Bromo-2-heptanal (S)-5-Bromo-2-heptanal (R)-5-Bromo-2-heptanone (S)-5-Bromo-2-heptanone (R)-3-Bromopentyl methyl ketone C Topic: Nomenclature 12. Which is the IUPAC name for the structure shown below? O A) B) C) D) E) Ans: 5-Cyclohexyl-2-hexanal 5-Cyclohexyl-2-hexanone 5-Cyclohexyl-5-methyl-2-pentanone 5-(1-Methylcyclohexyl)-2-pentanone 4-(1-Methylcyclohexyl)-2-butanone E 575 Chapter 16 Topic: New Functional Groups 13. Which of the following compounds is an acetal? O OCH3 A) B) C) D) E) Ans: O O O O I I II III IV None of these C OH II O O O IV III Topic: New Functional Groups 14. Which is the general formula for a thioacetal? H A) B) RC S RCHSR' C) OH RCHSR' D) SH RCHSR' E) SR' RCHOR' SR' Ans: D Topic: New Functional Groups 15. Which compound is an acetal? O O O I A) B) C) D) E) Ans: OH O II OCH3 OH O III I II III IV All of the above B 576 IV Chapter 16 Topic: Reaction Products 16. The product, C, of the following reaction sequence, O CH3CCH3 + A) CH3 CH2 B) C) CN HCN C4H7NO H2O H2SO4 heat C would be: CCOOH CH3CH2COOCH3 CH3CHCH3 CN D) CH3CH=CHCOOH E) None of these Ans: A Topic: Reaction Products 17. The product, H, of the following reaction sequence, O C6H5CH2Br + (C6H5)3P would be: A) F CH3 C6H5CH2CC6H5 B) OH O C) C6H5CH2CC6H5 C6H5CH CHCC6H5 O D) E) C6H5CH2CH=CHC6H5 C6H5CH CCH3 C 6H 5 Ans: E 577 C6H5Li ether G C6H5CCH3 H Chapter 16 Topic: Reaction Products 18. What would be the product of the following reaction sequence? OH i) PCl3 ? ii) C6H6, AlCl3 O iii) Zn(Hg), HCl, heat O O OH OH I II IV A) B) C) D) E) Ans: III V I II III IV V E Topic: Reaction Products 19. What new compound will be formed when HCl is added to a solution of pentanal in methanol? O A) O O B) Cl OH C) D) OH O O Cl E) O Ans: A 578 Chapter 16 Topic: Reaction Products 20. What would be the product of the following reaction sequence? OH O i) PCl3 ii) C6H6, AlCl3 iii) NaBH4, H2O ? O OH II I III OH OH IV A) B) C) D) E) Ans: V I II III IV V D 579 Chapter 16 Topic: Reaction Products 21. The product, K, of the following sequence of reactions CH3 Benzene CH3CHCOCl I AlCl3 OH CH3CH2MgBr ether H3O+ J K would be: OH HO O O I A) B) C) D) E) Ans: II III IV V I II III IV V B Topic: Reaction Products 22. Dissolving benzaldehyde in methyl alcohol establishes an equilibrium with what compound? OH A) B) C6H5CHOCH3 O C6H5COCH3 C) D) E) Ans: C6H5C(OCH3)3 Answers A) and B) Answers B) and C) A 580 Chapter 16 Topic: Reaction Products 23. Predict the major organic product of the following reaction: H Ag(NH3)2+ O ? H2O O O O HO2C O O H3C I A) B) C) D) E) Ans: H OH O II H H 3C H 3C III O O IV V I II III IV V B Topic: Reaction Products 24. The product, E, of the following reaction sequence, PCl5 C6H6 CH3CH2COOH C D AlCl3 CH2CH2CH3 I A) B) C) D) E) Ans: NaBH4 CH3OH E would be: O OH O COCH2CH3 CHCH2CH3 CCH2CH3 CH(CH3)2 IV V II III I II III IV V C 581 Chapter 16 Topic: Reaction Products 25. Select the structure of the major product in the following reaction. i) BH3 ? ii) H2O2,OH-, H2O A) B) C) D) E) Ans: Ethylbenzene 1-Phenylethanol Acetophenone 2-Phenylethanal Vinylbenzene D Topic: Reaction Products 26. Select the structure of the major product in the following reaction. H2SO4 HgSO4, H2O A) B) C) D) E) Ans: ? Ethylbenzene 1-Phenylethanol Acetophenone 2-Phenylethanal Vinylbenzene C Topic: Reaction Products 27. Select the structure of the major product in the following reaction. i) H2, Lindlar catalyst ii) O3 iii)Zn, CH3CO2H A) B) C) D) E) Ans: 4-methylhexanal 4-methyl-1-hexanol 3-methylhexanal 4,10-dimethyldodecane-6,7-dione 4,10-dimethyldodecane-6,7-diol A 582 ? Chapter 16 Topic: Reaction Products 28. The product, J, of the following reaction sequence, CH3CHCOOH SOCl2 (CH3)2CuLi I ether CH3 O A) CH3CHCOCH3 CH3 OH O B) CH3C CCH3 C) CH3 CH3CHCOCu D) CH3 O CH3CHCCH3 CH3 O E) CH3CHCCHCH3 CH3 CH3 Ans: D 583 J would be: Chapter 16 Topic: Reaction Products 29. What is the major product of the following reaction sequence? O HCN H2SO4 H2O heat CN NOSO3H CN COH H OSO3H CNH2 O I A) B) C) D) E) Ans: II III I II III IV V B 584 IV V Chapter 16 Topic: Reaction Products 30. The product, D, of the following sequence of reactions O SOCl2 CH3CH2COH A toluene AlCl3 Zn(Hg) B D HCl + C (discard) would be: O CH3 CH2CH2CH3 CH3CH2CCH2 I CH3 II CH3 CH2CH2CH2Cl CH2CH2CCl III CH3 CH CH3 CH3 IV A) B) C) D) E) Ans: O V I II III IV V A Topic: Reaction Products 31. What new compound will be formed when gaseous HCl is added to a solution of propanal in methanol? O A) B) CH3CH2COCH3 O CH3CH2COH C) D) CH3CH2CH(OCH3)2 CH3CH2CHOCH3 OH E) None of the above Ans: C 585 Chapter 16 Topic: Reaction Products 32. What is the product of the following reaction sequence? PCC C6H5CH2OH A) B) BrCH2CO2Et, Zn CH2Cl2 C6H5CH2OCH2CO2Et H 3O + benzene O C) C6H5COCH2CO2Et OH D) C6H5CHCH2CO2Et OH C6H5CHOCH2CO2Et E) C6H5CH2CH2CO2Et Ans: C Topic: Reaction Products 33. What would be the final product? O (C6H5)3P CH3I A) C6H5Li C6H5CCH3 ether C6H5C CH2 CH3 C6H5 B) C6H5CCH3 CH3 C) D) C6H5CH=CHCH3 OH C6H5CCH3 E) CH3 C6H5CH CC6H5 CH3 Ans: A 586 ? Chapter 16 Topic: Reaction Products 34. What is the major product of the following reaction sequence? OH, HCl OCH3 i) HO ? O ii) LAH, Et2O O iii) H2O, H3O + O OH OH O HO O HO I II III OH OH O O IV A) B) C) D) E) Ans: V I II III IV V E Topic: Reaction Products 35. An aldehyde results from the reaction of which of these compounds with aqueous base? A) CH3CH2CH2Cl B) CH3CHClCH2Cl C) CH3CH=CCl2 D) CH3CH2CHCl2 E) CH3CCl2CH3 Ans: D 587 Chapter 16 Topic: Reaction Products 36. The Baeyer-Villiger oxidation of propiophenone (ethyl phenyl ketone) produces chiefly: O A) B) CH3CH2OCC6H5 O C) CH3CH2OCOC6H5 O D) p-HOC6H4CCH2CH3 O E) C6H5OCCH2CH3 O C6H5CCH2CH2OH Ans: D Topic: Reaction Products 37. What is compound V in the following synthesis? 1. ether O Cl + V (C6H5)3P + W A) B) C) D) E) Ans: O 2. H3O+ C6H5Li ether Wittig reagent CH3CH2COCl CH3CH2MgBr CH3COCl (CH3)2CuLi (CH3CH2)2CuLi E 588 Chapter 16 Topic: Reaction Products 38. What is the reactant W in the synthesis given below? 1. ether O O + V Cl 2. H3O+ (C6H5)3P + W A) B) C) D) E) Ans: C6H5Li Wittig reagent ether Cyclopentanone Cyclopentene Cyclopentanol Bromocyclopentane Triphenylphosphine oxide D Topic: Reaction Products 39. What is the final product, Z, of the following synthesis? 1. KMnO4, CH3 heat X 2. H3O+ SOCl2 Y 1. LiAlH(O-t-Bu)3 ether, -78 oC 2. H2O O O O O O COAl(t-Bu)2 COCH3 CH COLi COH I A) B) C) D) E) Ans: OH-, II III I II III IV V C 589 IV V Z Chapter 16 Topic: Reaction Products 40. What is the final product of this synthetic sequence? Br2 Mg FeCl3 ether Benzene 1. C6H5CHO H2Cr2O4 2. H3O+ acetone ? O A) C6H5CC6H5 B) C) D) p-BrC6H4CH2C6H5 C6H5CH2COOH O C6H5CH2CC6H5 E) C6H5CH2C6H5 Ans: A Topic: Reaction Products 41. The reaction of tert-butyl methyl ketone with a peroxy acid produces which of these as the principal product(s)? O A) B) (CH3)3COCCH3 O C) (CH3)3CCOCH3 CH3 (CH3)2C COCH3 O D) E) (CH3)3COH + HO2CCH3 O (CH3)3COCOCH3 Ans: A 590 Chapter 16 Topic: Synthesis 42. Which of the following reactions would yield benzaldehyde? OHA) C6H5CH2Cl H2O heat B) H3O+ C6H5CH(OCH3)2 C) 1. LiAlH4, ether C6H5COOH 2. H2O D) Answers A) and B) E) Answers A), B), and C) Ans: B Topic: Synthesis 43. Which of the reactions listed below would serve as a synthesis of acetophenone, O ? C6H5CCH3 A) O + (CH3)2CuLi AlCl3 B) C6H6 + CH3COCl ether C) C6H5CN + CH3Li D) Answers A) and B) only E) Answers A), B), and C) Ans: E C6H5CCl H 3O + Topic: Synthesis 44. Which of the following would yield 3-pentanone as the major product? ether A) H 3O + CH3CH2CN + CH3CH2Li Product ether B) H 3O + CH3CH2CO2H + 2 CH3CH2Li Product O C) ether CH3CH2CCl + (CH3CH2)2CuLi D) Two of these E) All of these Ans: E 591 Chapter 16 Topic: Synthesis O 45. Which of the following procedures would not yield (CH3)2CHCH as a product? PCC I OH CH2Cl2 SOCl2 II CO2H Zn HOAc KMnO4 IV V ether, -78 oC O3 III LiAlH(O-t-Bu)3 OH O H3O+ NaOH H3O+ O A) B) C) D) E) Ans: I II III IV V D 592 Chapter 16 Topic: Synthesis 46. Which of the following procedures would not yield 3-pentanone as a major product? CH3CH2MgBr A) H3O+ CH3CH2CN ether O B) 2 CH3CH2Li H2O CH3CH2COH C) CH3CH2CN H3O+ ether O D) CH3CH2CCl E) ether CH3CH2Li CH3CH2CO2H (CH3CH2)2CuLi ether CH3CH2MgBr H3 O+ ether Ans: E Topic: Synthesis 47. How could the following synthetic conversion be accomplished? O CH3CH2CCH3 CH3CH2CH2CHO A) HgSO4/H2SO4; then PCl5/0°C; then NaNH2, liq. NH3 B) PCl5/0°C; then NaNH2, liq. NH3; then Sia2BH; then H2O2 C) PCl5/0°C; then NaNH2, liq. NH3; then HgSO4, H2SO4/H2O D) NaNH2, liq. NH3; then PCl5/0°C; then HgSO4, H2SO4/H2O E) H2O2; then PCl5/0°C; then NaNH2, liq. NH3; then Sia2BH Ans: C 593 Chapter 16 Topic: Synthesis 48. Which sequence of reactions would be utilized to convert O CO2CH3 into CH3 C CH3 O ? OH A) B) C) D) E) Ans: 2CH3MgBr, then NH4+ HOCH2CH2OH, H3O+; LiAlH4, ether; 2CH3MgBr, then NH4+ HOCH2CH2OH, H3O+; 2CH3MgBr, then NH4+ HOCH2CH2OH, H3O+; H2, Pt; CH3OH, NH4+ None of the above C Topic: Synthesis 49. Which reaction sequence would be used to prepare ? I O + MgBr O II H III IV A) B) C) D) E) Ans: + 2 CH3MgBr (C6H5)3P 1. ether H2 2. H3O+ Ni 1. ether H2 2. H3O+ Ni C6H5Li cyclopentanone Cl H2 Ni O CH3MgBr H3O+ ether I II III IV All of the above would yield the product. C 594 Chapter 16 Topic: Synthesis 50. Which Wittig reagent would be used to synthesize ? CH3CH=P(C6H5)3 A) B) C) D) E) Ans: CH=P(C6H5)3 I II I II III IV Either I or II could be used. E P(C6H5)3 III 595 CH3CH2CH=P(C6H5)3 IV Chapter 16 Topic: Synthesis 51. A good synthesis of H O would be: H H2O, H2SO4 I HgSO4 H 1. Sia2BH II 2. H2O2, NaOH H 1. O3 III 2. Zn, HOAc OH IV A) B) C) D) E) Ans: 1. KMnO4, NaOH, heat 2. H3O+ I II III IV All of these are equally useful. B 596 Chapter 16 Topic: Synthesis 52. Which of the following is not a synthesis of benzophenone, O C6H5CC6H5 ? O A) C6H6 + C6H5CCl B) C) (C6H5)2CHOH (C6H5)2CH=CH2 AlCl3 H2CrO4 acetone 1. O3 2. Zn, HOAc 1. ether D) (C6H5)2CO2H + 2 C6H5Li 2. H2O E) All of the above will give benzophenone. Ans: E Topic: Synthesis 53. Which of the following is a synthesis of 3-heptanone? A) PCC 1. CH3CH2MgBr H2Cr2O4 CH3CH2CH2CH2CH2OH acetone CH2Cl2 2. H3O+ + CH3(CH2)2CH2Li B) H3 O CH3CH2CN ether PBr3 CH3CH2MgBr C) H3 O+ NaCN CH3CH2CH2CH2OH ether ether + KMnO4 2 CH3CH2Li D) H2 O H3O CH3CH2CH2CH2CH2OH OH-, ether E) All of the above are syntheses of 3-heptanone. Ans: E 597 Chapter 16 Topic: Synthesis 54. Which synthesis or syntheses would yield propanal? PCC A) CH3CH2CH2OH CH2Cl2 O B) LiAlH[OC(CH3)3]3 CH3CH2CCl C) CH3C CH ether, -78 oC 1. Sia2BH 2. H2O2, OH- D) All of these E) None of these Ans: D Topic: Reagents 55. LiAlH4 (LAH) cannot be used to convert carboxylic acids to the corresponding aldehydes because: A) LAH is not sufficiently reactive. B) RCOOH is converted into RCOOLi. C) RCOOH is reduced to RCH2OH. D) RCOOH is reduced to RCH3. E) RCOOH is converted into R2C=O. Ans: C Topic: Reagents 56. The following reduction can be carried out with which reagent(s)? ? O A) B) C) D) E) Ans: Zn(Hg), HCl i) HSCH2CH2SH, BF3 ; ii)Raney Ni (H2) NaBH4, CH3OH A&B A&C D 598 Chapter 16 Topic: Reagents 57. Identify the reagent(s) that would bring about the following reaction: CH3CH2CH2COCl ⎯⎯⎯→ CH3CH2CH2CHO A) H2/Ni B) Li/liq.NH3 C) LiAlH[OC(CH3)3]3, ether D) NaBH4, CH3OH E) LiAlH4, ether Ans: C Topic: Reagents 58. Which reagent will not differentiate between 3-butenal and 2-butanone? A) Br2/CCl4 B) Ag2O,OHC) H2NNHC6H5 D) KMnO4,OHE) None of these Ans: C Topic: Reagents 59. The Reformatsky reaction involves the reaction of an aldehyde or ketone with: A) RLi B) R2CuLi R C) XZnCHCO2R' D) RC≡CNa E) R3P Ans: C Topic: Reagents 60. Acetals are unstable in the presence of an aqueous solution of which of these? A) HCl B) NaOH C) KHCO3 D) Na2CO3 E) NaCl Ans: A 599 Chapter 16 Topic: Reagents H 61. H The compound C6H5C N N CC6H5 is produced by the reaction of an excess of benzaldehyde with which compound? A) Ammonia B) Hydrazine C) Nitrogen D) Phenylhydrazine E) Hydroxylamine Ans: B Topic: Reagents 62. Which of these will not catalyze the reaction of a weak nucleophile with the carbonyl group of an aldehyde or ketone? A) IB) H3O+ C) AlCl3 D) BF3 E) ZnCl2 Ans: A Topic: Reagents 63. Which reagent(s) could be used to carry out the following transformation? O ? A) B) C) D) E) Ans: Zn(Hg), HCl, reflux LiAlH4, ether HSCH2CH2SH, BF3; then Raney Ni (H2) All of the above Two of the above E 600 Chapter 16 Topic: Physical Properties, Relationships, Stereochemistry 64. Which of the compounds listed below would you expect to have the highest boiling point? (They all have approximately the same molecular weight.) A) pentane B) 1-butanol C) Butanal D) 1-fluorobutane E) diethylether Ans: B Topic: Physical Properties, Relationships, Stereochemistry 65. What is the order of decreasing reactivity of aldehydes, esters and ketones towards the organozinc compounds used in the Reformatsky reaction? A) Aldehydes > esters > ketones B) Esters > aldehydes > ketones C) Ketones > esters > aldehydes D) Ketones > aldehydes > esters E) Aldehydes > ketones > esters Ans: E Topic: Physical Properties, Relationships, Stereochemistry 66. What, in general, is the order of decreasing reactivity of these carbonyl compounds towards nucleophilic reagents? O CH3CCH3 H CH3C O O I II A) I > III > V > II > IV B) IV > II > I > III > V C) V > III > I > II > IV D) II > I > V > III > IV E) III > V > IV > II > I Ans: B (CH3)3CCCH3 III 601 H HC IV O O (CH3)3CCC(CH3)3 V Chapter 16 Topic: Physical Properties, Relationships, Stereochemistry 67. Which of these gem-diols is expected to be the most stable? OH A) CF3CCF3 OH B) C) CH3CH(OH)2 OH CH3CCH3 OH D) C6H5CH(OH)2 E) ClCH2CH(OH)2 Ans: A Topic: Physical Properties, Relationships, Stereochemistry 68. The relationship of 3-methyl-2-heptanone and 3-methyl-2-hepten-2-ol is designated by the term: A) Tautomers B) Conformational isomers C) Diastereomers D) Resonance structures E) Stereoisomers Ans: A 602 Chapter 16 Topic: Physical Properties, Relationships, Stereochemistry . 69. In which of the following reactions is the final product expected to be formed as a racemic mixture? H A) C6H5MgBr + C6H5C O O B) HCN + C) H D) CH3CH2C H CH3C CH3CCH3 O O + BrZnCH2COC2H5 + xs CH3OH + HCl O O E) CH3CHCH2COC2H5 + (i-Bu)2AlH CH3 Ans: C Topic: Physical Properties, Relationships, Stereochemistry 70. Stereoisomers can exist in the case of which of the following? A) The hydrazone of butanone B) The oxime of acetone C) The phenylhydrazone of cyclohexanone D) The cyclic acetal formed from propanal and ethane-1,2-diol E) The imine of cyclopentanone Ans: A Topic: Physical Properties, Relationships, Stereochemistry 71. Stereoisomers can exist in the case of which of the following? A) The hydrazone of acetophenone B) The oxime of 2-methylcyclopentanone C) The phenylhydrazone of 4-methylcyclohexanone D) The imine of cyclopentanone E) Two of the above Ans: B 603 Chapter 16 Topic: Reactions of Aldehydes and Ketones 72. Which of the following is formed when 3-methylcyclopentanone reacts with hydroxylamine? N-NH-C6H5 N-NH2 I N-OH II III NO2 O N N H N NH2 N H IV A) B) C) D) E) Ans: NO2 V I II III IV V C Topic: Reactions of Aldehydes and Ketones 73. Which of the following is formed when 3-methylcyclopentanone reacts with semicarbazide? N-NH-C6H5 N-NH2 I N-OH II III NO2 O N N H NH2 N N H IV A) B) C) D) E) Ans: V I II III IV V D 604 NO2 Chapter 16 Topic: Reactions of Aldehydes and Ketones 74. Which of the following is formed when 4-methylpentanal reacts with phenylhydrazine? N-C6H5 N-NH-C6H5 I N-NH2 II III O N N H N=N-C6H5 NH2 V IV A) B) C) D) E) Ans: I II III IV V A Topic: Reactions of Aldehydes and Ketones 75. Which of the following is formed when 2,2,3-trimethylcyclohexanone reacts with hydroxylamine? N-NH-C6H5 N-NH2 I N-OH III II NO2 O N N H NH2 N N H IV A) B) C) D) E) Ans: V I II III IV V C 605 NO2 Chapter 16 Topic: Reactions of Aldehydes and Ketones 76. Which of the following is formed when 2,2,3-trimethylcyclohexanone reacts with semicarbazide? N-NH-C6H5 N-NH2 I N-OH III II NO2 O N N H N NH2 N H IV A) B) C) D) E) Ans: NO2 V I II III IV V D Topic: Reactions of Aldehydes and Ketones 77. Which of the following is formed when 2,2,3-trimethylcyclohexanone reacts with hydrazine? N-NH-C6H5 N-NH2 I N-OH III II NO2 O N N H NH2 N N H IV A) B) C) D) E) Ans: V I II III IV V B 606 NO2 Chapter 16 Topic: NMR 78. A compound with formula C5H10O gives two signals only, both singlets, in the 1H NMR spectrum. Which of these structures is a possible one for this compound? O A) B) CH3CH2CCH2CH3 O C) (CH3)2CHCCH3 H (CH3)3CC D) O H CH3CH2CHC O CH3 H E) (CH3)2CHCH2C O Ans: C Topic: NMR 79. The 1H NMR spectrum of a compound with formula C7H14O gives three signals. Which of these structures is a possible one for this compound? A) 2-heptanone B) 3-heptanone C) 2,4-dimethyl-3-pentanone D) 2,2-dimethyl-3-pentanone E) two of the above Ans: E 607 Chapter 16 Topic: NMR 80. The 13C NMR spectrum of a compound with formula C7H14O gives three signals. Which of these structures is a possible one for this compound? A) 2-heptanone B) 3-heptanone C) 2,2-dimethyl-3-pentanone D) 2,4-dimethyl-3-pentanone E) two of the above Ans: D Topic: NMR 81. The 1H NMR spectrum of a compound with formula C7H14O gives a doublet at 9.2 ppm. Which of these structures is a possible one for this compound? A) 2-methyl-3-hexanone B) 2-methylhexanal C) 2,2 -dimethylpentanal D) 2,2-dimethyl-3-pentanone E) two of the above Ans: B SHORT ANSWER QUESTIONS Topic: Relative Reactivity 82. Aldehydes are more reactive than ketones towards nucleophilic substitution because of both steric and electronic factors. Briefly explain. a. Steric reasons: ______________. b. Electronic reasons: __________. Ans: a. aldehydes have the small hydrogen substituent on one side, so less steric crowding than ketones b. aldehydes have only one electron-releasing group to partly neutralize/stabilize the partial positive charge at the carbonyl carbon while ketones have two Topic: General 83. A compound with an OH and OR group attached to the same carbon is known as a(n) _____________. Ans: hemiacetal 608 Chapter 16 Topic: General 84. A compound with two OH groups attached to the same carbon is known as a(n) _________. Ans: hydrate or gem-diol Topic: General 85. A compound with two OR groups attached to the same carbon is known as a(n) _________. Ans: acetal Topic: General 86. A compound containing a C=N double bond is known as a(n) __________. Ans: imine Topic: General 87. A compound with an OH and CN group attached to the same carbon is known as a(n) _____________. Ans: cyanohydrin Topic: Wittig Reaction 88. The reaction between a phosphorus ylide and an aldehyde or ketone is called the ___________ reaction. Ans: Wittig Topic: Wittig Reaction 89. The driving force for the Wittig reaction is the formation of the very strong _______________ bond in _______________. Ans: P-O bond; triphenylphosphine oxide Topic: General 90. A “green” version of the __________________ uses a tin-zeolite catalyst with hydrogen peroxide. Ans: Baeyer-Villiger oxidation 609 Chapter 16 Topic: Functional Group Tests 91. 2,4-DNP is a reagent frequently used for functional group tests; it detects the presence of _____________. Ans: aldehydes and ketones Topic: Functional Group Tests 92. The Tollens test, used in conjunction with 2,4-DNP, can distinguish between ______________ and _______________. Ans: aldehydes and ketones Topic: Functional Group Tests 93. What reagent would help you distinguish between acetophenone and 2methylbenzaldehyde? Ans: Tollen’s Reagent Topic: Functional Group Tests 94. Oximes are formed when aldehydes and ketones react with _______________. Ans: Hydroxylamine, NH2OH Topic: Synthetic Strategy 95. Suggest a synthetic strategy for the synthesis of 3-heptanone from 1-bromobutane. i. C2H5Li, Et2O Ans: NaCN Br CN ii. H3O+ O Topic: Synthetic Strategy 96. Suggest a synthetic strategy for the synthesis of 4-methylpentanal from 3-methyl-1bromobutane. Ans: i. DIBAL-H O NaCN CN Br ii. H2O 610 Chapter 16 Topic: Synthetic Strategy 97. Suggest a synthetic strategy for the synthesis of 6-methyl-3-heptanol from 4methylpentanenitrile, (CH3)2CHCH2CH2CN. Ans: i. DIBAL-H CN ii. H2O OH iii. C2H5MgBr, Et2O iv. H3O+ OR i. C2H5MgBr, Et2O CN ii. H3O+ OH iii. NaBH4, H2O Topic: Reaction Sequence 98. Complete the following reaction sequence, giving structural details of all significant intermediates. i. Br2, hν ? ii. Mg, CH3CH2CN iii. H3O+ iv. RCO3H O Ans: Br2, hν Br i. Mg, CH CH CN 3 2 ii. H3O+ RCO3H O O 611 Chapter 16 Topic: Reaction Sequence 99. Complete the following reaction sequence, giving structural details of all significant intermediates. i. O3 i. EtMgBr ? + ii.Zn, CH3CO2H ii. H3O , heat O Ans: O i. EtMgBr ii. H3O+, heat i. O3 ii.Zn, CH3CO2H HO O O Topic: NMR 100. Explain clearly how you might use 1H NMR to distinguish between 2-phenylacetaldehyde and acetophenone Ans: A quick inspection of 1H NMR of the two substances would allow easy identification and distinction between them: the expected 1H NMR spectra of the two substances are described below. 2-Phenylacetaldehyde Acetophenone and C6H5COCH3 C6H5CH2CHO 3 signals 2 signals approximate δ ppm approximate δ ppm singlet (-CH3) 2.0 doublet (-CH2-) 2.5 multiplet (C6H5) 7.2 multiplet (C6H5) 7 doublet (-CHO) 9 612 Chapter 17 MULTIPLE CHOICE QUESTIONS Topic: Acid/Base 1. Which compound would be most acidic? A) CH3CH2CH3 B) CH3CH=CH2 C) Cyclohexane (CH3)2C=O D) (CH3)2C=O E) Benzene Ans: D Topic: Reaction Products 2. What would be the major product of the following reaction? O C6H5CH O + CH3CH OHheat O A) B) C6H5CH2CCH3 O O C) C6H5CCH2CH OH OH D) C6H5CHCH2CH2 O E) C6H5CH2CH2CH O C6H5CH=CHCH Ans: E 613 Chapter 17 Topic: Reaction Products 3. The product, C, of the following sequence of reactions, CH3 CH3CCHO + CH3CH2CHO OH- A CH3 would be: CH3 A) CH3CCH=CHCH2CH2OH CH3 CH3 B) CH3CCH=CCH2OH CH3 CH3 CH3 C) CH3CCH2CH2CH2OH CH3 CH3 D) CH3CCH2CH2CH2CH2OH CH3 CH3 E) CH3CCH2CHCHO CH3 CH3 Ans: B 614 H3O+ (-H2O) B NaBH4 CH3OH C Chapter 17 Topic: Reaction Products 4. What would be the major product of the following reaction? O O CH3 CH3CCH3 + OH- CH O CH3 C CH ? 100 oC O CH3 CH CH3 CH CH3 C CH3 CH3 I OH II III O CH3 CH OH CHCCH3 CH3 CHC(CH3)2 OH IV A) B) C) D) E) Ans: V I II III IV V D Topic: Reaction Products 5. What would be the major product of the following reaction? O OH- ? H2O CH3CH2CH2OH + CH3CH2COO- CH3CH2CH A) B) CH3CH2CHCH2CHO OH O C) D) CH3CH2CH2OCCH2CH3 CH3CH2CHCHCHO HO CH3 O E) CH3CH2CHCCH2CH3 HO Ans: D 615 CHCH2CCH3 Chapter 17 Topic: Reaction Products 6. What would be the major product of the following reaction? OHO ? + O OH O O O O OH I II III OH OH O O IV A) B) C) D) E) Ans: V I II III IV V D 616 Chapter 17 Topic: Reaction Products 7. What would be the major product of the following reaction? O + O OHheat O O HO O O OH I III II HO O IV A) B) C) D) E) Ans: ? V I II III IV V D 617 O Chapter 17 Topic: Reaction Products 8. What would be the major product, B, of the following reaction sequence? O + OHheat O A i. CH3Cu ii H3O+ B O O O OH I II III O OH IV A) B) C) D) E) Ans: V I II III IV V C 618 Chapter 17 Topic: Reaction Products 9. What would be the major product, B, of the following reaction sequence? O + OHheat O A B O OH OH OH I OH II III OH OH IV A) B) C) D) E) Ans: NaBH4 H2O V I II III IV V C 619 Chapter 17 Topic: Reaction Products 10. What would be the major product of the following reaction? O CH3 OD? + D2O room C6H5C CHCH3 temp. O CD A) 3 B) C 6 H 5C O CHCH3 CH3 C) C 6H 5 C O CDCH3 CH3 D) C 6D 5 C O CDCH3 CD3 E) C 6H 5 C CDCD3 OD C6H5CDCHCH3 CH3 Ans: B Topic: Reaction Products 11. What would be the product of the following reaction? NaCN ? CH3CH=CO2C2H5 C2H5OH, CH3COOH CH3CH2CHCO2C2H5 A) CN B) C) D) CH3CH=CHCO2CN CH3CH=CHCN CH3CHCH2CO2C2H5 CN CN E) CH3CH=CHCOC2H5 OH Ans: D 620 Chapter 17 Topic: Reaction Products 12. Select the structure of the major product formed in the following reaction. 1. CH3Cu (CH3)2C=CHCCH3 2. H2O (CH3)3CCH2COCH3 O A) B) C) (CH3)2C=CHC(CH3)2 OH (CH3)2CHCHCOCH3 CH3 D) 2 CH3CCH3 O OH E) (CH3)2C=CHCCH3 H Ans: A Topic: Reaction Products 13. What would be the product of the following reaction? O + CH3CH2CN C6H5CH=CHCH2CN C6H5CH A) B) EtO-, EtOH O C6H5CCHCN C) CH3 C6H5CH=CCN D) OH CH3 E) C6H5CHCH2CH2CN OH C6H5CCH2CH2CN OCH2CH3 Ans: C 621 ? Chapter 17 Topic: Reaction Products 14. What would be the final product of the following reaction sequence? O O C6H5CH A) B) + CH3CCH3 OH-, heat O C) C6H5CHCH2CCH3 O D) C6H5CH2CH2CCH3 OH E) C6H5CH=CHCHCH3 OH OH LiAlH4 ether C6H5CH2CH2CH2CH3 OH A C6H5CHCH2CHCH3 Ans: D 622 Final Product Chapter 17 Topic: Reaction Products 15. What would be the major product of the following reaction? O C6H5CCHCH2CH3 + Br2 H3O+ CH3 O A) C6H5CCBrCH2CH3 CH3 O Br B) C6H5CCHCHCH3 CH3 O OH C) C6H5CCHCHCH3 D) CH3 C6H5CBr2CHCH2CH3 CH3 O E) m-BrC6H4CCHCH2CH3 CH3 Ans: A 623 ? Chapter 17 Topic: Reaction Products 16. What would be the major product of the following reaction? O C6H5CH O + CH3CCH3 OH- ? heat O A) OH B) C6H5CCH2CHCH3 O O C) C6H5CCH2CCH3 OH OH D) C6H5CHCH2CHCH3 O O E) C6H5CCH2CCH3 O C6H5CH=CHCCH3 Ans: E Topic: Reaction Products 17. What would be the product, C, of the following reaction sequence? O O H2 H3O+ OHA B (CH3)3CCH + CH3CH2CH Ni heat A) B) (CH3)3CCH2CH2CH2OH O OH C) (CH3)3CCHCH2CH2CH (CH3)3CCH2CHCH2OH D) CH3 (CH3)3CCH=CCH2OH CH3 O E) (CH3)3CCH=CCH CH3 Ans: C 624 C Chapter 17 Topic: Reaction Products 18. What would be the product, C, of the following reaction sequence? O O + CH3CH2CH (CH3)3CCH A) B) OH- A H3O+ heat B CH2 (CH3)3CCH2CH2CH2OH OH C) (CH3)3CCHCH2CH=CH2 (CH3)3CCH2C=CH2 D) CH3 (CH3)3CCH=CCH=CH2 CH3 OH E) (CH3)3CCHCHCH=CH2 CH3 Ans: D Topic: Reaction Products 19. What would be the product, B, of the following reaction sequence? O C6H5CH A) B) + CH3CN EtO-, EtOH A (C9H7N) C6H5CH=CHCO2H O C6H5CCH2CO2H C) D) E) C6H5CH2CH2CO2H OH C6H5CHCH2CO2H OH C6H5CHCH2CN Ans: A 625 H3O+ heat B P(C6H5)3 C Chapter 17 Topic: Reaction Products 20. What would be the product, C, of the following reaction sequence? O O NaBH4 H3O+, heat OHA B C6H5CH + CH3CH2CH CH3OH (-H2O) 25 oC O A) C6H5CCHCH2OH B) CH3 C6H5CHCHCH2OH HO CH3 O C) C6H5CH2CHCH CH3 O D) C6H5CH=CCH E) CH3 C6H5CH=CCH2OH CH3 hi Ans: E 626 C Chapter 17 Topic: Reaction Products 21. What would be the product, C, of the following reaction sequence? O O H2, Ni H3O+, heat OHA B C6H5CH + CH3CH2CH (-H2O) high 25 oC pressure O A) C6H5CCHCH2OH B) CH3 C6H5CH2CHCH2OH CH3 O C) C6H5CH2CHCH CH3 O D) C6H5CH=CCH E) CH3 C6H5CH=CCH2OH CH3 Ans: B 627 C Chapter 17 Topic: Reaction Products 22. What would be the major product of the following reaction? O + CN- C6H5CH=CHCCH3 CH3CH2OH CH3COOH O A) C6H5CH2CHCCH3 CN O B) C6H5CHCH2CCH3 CN OH C) C6H5CH2CH2CCH3 CN O D) E) C6H5CH2CH2CCN OH C6H5CHCH=CCH3 CN Ans: B 628 ? Chapter 17 Topic: Reaction Products 23. What would be the major product(s) of the following reaction? O i. Cu ii. H3O+ O OH I O III II OH A) B) C) D) E) Ans: ? IV I and V II and IV I and III III and IV None of these A O V 629 Chapter 17 Topic: Reaction Products 24. What would be the major product of the following reaction? O O ? OHOH O O O O I O III II O O IV A) B) C) D) E) Ans: O V I II III IV V E 630 Chapter 17 Topic: Reaction Products 25. What would be the major product of the following reaction? i. Br2, NaOH ? ii. H3O+ O Br HO O O I O II Br Br O A) B) C) D) E) Ans: IV O V I II III IV V B 631 III Chapter 17 Topic: Reaction Products 26. What would be the major product of the following reaction sequence? O i. LDA ii. C2H5I ? O O O I II III O V IV A) B) C) D) E) Ans: I II III IV V I Topic: Synthetic Strategy 27. What synthetic strategy would accomplish the following transformation? ? O A) B) C) D) E) Ans: O i) Br2, H3O+; ii) NaOC2H5, C2H5OH, heat i) Cl2, FeCl3; ii) NaOC2H5, C2H5OH, heat i) HCN; ii) H3O+, heat i) Br2, hν; ii) (CH3)3COK, (CH3)3COH, heat i) Br2, H3O+; ii) (CH3)3COK, (CH3)3COH, heat A 632 Chapter 17 Topic: Reaction Products 28. What would be the major product of the following reaction? O CCHCH3 OH- + Br2 ? CH3 O CCHCH3 Br CH3 Br O O CCHCH3 CCBrCH3 CH3 I II III O O CCHCH2Br CCHCH2Br CH3 CH2Br IV A) B) C) D) E) Ans: CH3 V I II III IV V C Topic: Reaction Products 29. Which compound would be formed when 2-methylbutanal is treated with a solution of NaOD in D2O? CH3CH2CDCHO A) B) CH3 CH3CH2CHCDO C) CH3 CH3CHDCHCHO D) CH3 CH2DCH2CHCHO E) CH3 CH3CH2CDCDO CH3 Ans: A 633 Chapter 17 Topic: Reaction Products 30. Which compound would be formed when 2,3-dimethylhexanal is treated with a solution of NaOD in D2O? D A) O D B) O D D C) O D) O D E) O D Ans E Topic: Reaction Products 31. What is the final product of this reaction sequence? CH3CH2NO2 H2, Ni ? H2C=O OHNH2 A) CH3C=CH2 B) C) CH3CH2CH2NH2 NH2 CH3CHCH3 D) E) CH3CH2CH2NO2 NO2 CH3CHCH3 Ans: C 634 Chapter 17 Topic: Reaction Products 32. Which of these is a product of the reaction of C6H5MgBr with O C6H5CH=CHCCH3 O A) ? C6H5CH=CCCH3 C 6H 5 OH B) C6H5CH=CHCCH3 C6H5 O C) C6H5CH=CHCCH2C6H5 O D) p-C6H5 E) C6H4 CH=CHCCH3 OC6H5 C6H5CH=CHCHCH3 Ans: B Topic: Reaction Products 33. What is the product of the reaction below? O 1. (C6H5)2CuLi ? 2. H2O O O HO C6H5 C6H5 C6H5 A) B) C) D) E) Ans: I I II III IV V B II O O C6H5 C6H5 III 635 IV V Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 34. Which reagents would you use to synthesize this compound by an aldol condensation? O C6H5CH=CHCC6H5 O O A) and C6H5CH B) and C6H5CH2CH C6H5CCH3 O C) D) C6H5CH2CH O O C6H5CH=CHCH O C6H5CCH3 and and C6H5OH O C6H5CH O E) (C6H5)2CuLi and CH2=CHCC6H5 Ans: D Topic: The Aldol Reaction/Condensation (Explicitly Identified) 35. What starting compound(s) would you use in an aldol reaction to prepare O CH OH O O ? O O O CH3CHCH2CH2CCH3 CH3CCH2CH2CCH3 CH3CCH2CH2CH2CH I II III O O O HCCH2CH2CH2CH IV A) B) C) D) E) Ans: + H2C=O V I II III IV V D 636 Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 36. Which reagents would you use to synthesize this compound by an aldol condensation? O C6H5CH=CCH C6H5 O A) O and C6H5CH and C6H5CH2CH C6H5CCH3 O C) D) C6H5CH2CH O O B) C6H5CH=CHCH O C6H5CCH3 E) and and C6H5OH O C6H5CH O C6H5CH2Cl and C6H5CHCH ONa Ans: A Topic: The Aldol Reaction/Condensation (Explicitly Identified) 37. The aldol condensation product formed from 3-pentanone in the presence of base has the IUPAC name: A) 5-Ethyl-4-methyl-4-hepten-3-one B) 5-Ethyl-4-methyl-5-hepten-3-one C) 4-Methyl-4-nonen-3,7-dione D) 3-Ethyl-4-methyl-3-hepten-5-one E) 3-Ethyl-4-methyl-2-hepten-5-one Ans: A 637 Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 38. Which of these is not among the reaction products when a crossed aldol addition occurs between ethanal and butanal? OH H A) B) CH3CHCH2C=O OH H CH3CH2CH2CHCHCH2C=O CH2CH3 H OH C) CH3CHCHC=O D) CH2CH3 OH E) CH3CH2CH2CHCH2C=O OH H H CH3CH2CH2CHCHC=O CH2CH3 Ans: B Topic: The Aldol Reaction/Condensation (Explicitly Identified) H 39. C6H5CH=CC=O CH2CH3 The retro-aldol reaction of H A) B) C6H5CH2CH2C=O H C) C6H5CH2C=O H C6H5C=O H + + + CH3C=O H CH3CH2C=O O CH3CH2CC=O H O D) C6H5CH2CCH2CH3 H H E) C6H5C=O + H2C=O + CH3CH2CH2C=O Ans: E 638 gives: Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 40. If butanal is added slowly to an aqueous solution of sodium hydroxide and 2,2dimethylpropanal at 25°C, the principal product is which of these? OH H A) (CH3)3CCHCHC=O CH2CH3 OH H B) CH3CH2CH2CHCHC=O CH2CH3 OH C) (CH3)3CCHCC(CH3)3 O OH D) E) CH3CH2CH2CHC(CH3)3 OH H CH3CH2CH2CHCHC=O C(CH3)3 Ans: A 639 Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 41. What compound results from the aldol cyclization of O O CH3CCH2CH2CHCH2CCH3 ? CH3 CH3 CH3 CH3 O CH3 O CH3 CH3 O CH3 CH3 CH3 CH3 I A) B) C) D) E) Ans: O II III IV I II III IV Both III and IV E Topic: The Aldol Reaction/Condensation (Explicitly Identified) O 42. H The aldol cyclization of CH3CCH2CH2CH2C=O produces which of these? O C CH3 I A) I B) II C) III D) IV E) V Ans: D H CH3 H O C=O II O C=O III 640 CH3 O IV O V Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 43. What product results from the intramolecular aldol reaction of 2,5-hexanedione? O O O CH3 CH3 CCH3 CH3 I A) B) C) D) E) Ans: CH3 CH3 CCH3 O II III O IV V I II III IV V A Topic: The Aldol Reaction/Condensation (Explicitly Identified) O 44. O The reaction of CH3CCH2CH2CH2CCH3 with base affords which of these products? H CH3 C=O H CH3 O O A) B) C) D) E) Ans: O C=O CH3 I O II III I II III IV V D 641 CH3 IV V Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 45. The aldol reaction of cyclohexanone produces which of these self-condensation products? O O A) B) C) D) E) Ans: O I I II III IV V B O II O O III IV V Topic: The Aldol Reaction/Condensation (Explicitly Identified) 46. Which is the only one of these compounds which cannot self-condense in the presence of dilute aqueous alkali? A) Phenylethanal B) Propanal C) 2-Methylpropanal D) 3-Methylpentanal E) 2,2-Dimethylpropanal Ans: E Topic: The Aldol Reaction/Condensation (Explicitly Identified) 47. Which is the only one of these compounds which cannot self-condense in the presence of dilute aqueous alkali? A) Phenylethanal B) 2-methyl-3-pentanone C) 2-Methylpentanal D) Acetophenone E) 2,2-Dimethylpentanal Ans: E 642 Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) 48. Which of these compounds cannot self-condense in the presence of dilute aqueous alkali? A) 3-(4-Nitrophenyl)propanal B) 2-methyl-3-pentanone C) 2-(4-Nitrophenyl)propanal D) 3-(4-Nitrophenyl)-2-butanone E) All of the above compounds can self-condense Ans: E Topic: The Aldol Reaction/Condensation (Explicitly Identified) 49. Which of these compounds can react with 4-methylhexanal to afford good yields of the crossed aldol product? A) 3-(4-Nitrophenyl)propanal B) 2-methyl-3-pentanone C) 2-(4-Nitrophenyl)propanal D) 3-(4-Nitrophenyl)-2-butanone E) None of the above compounds will give good yields of the crossed aldol product with 4-methylhexanal Ans: E Topic: The Aldol Reaction/Condensation (Explicitly Identified) 50. Which of these compounds can react with 4-methylpentanal to afford good yields of the crossed aldol product? A) 3-(4-Nitrophenyl)propanal B) 2ethyl-2-methylheptanal C) 2-(4-Nitrophenyl)propanal D) 3-(4-Nitrophenyl)-2-butanone E) None of the above compounds will give good yields of the crossed aldol product with 4-methylhexanal Ans: B 643 Chapter 17 Topic: The Aldol Reaction/Condensation (Explicitly Identified) O 51. O When CH3CCH2CH2CH2CH2CH2CCH3 cyclizes in basic solution, which of these compounds will be formed? O C CH3 O C CH3 C CH3 I A) B) C) D) E) Ans: O CH3 CH3 O O O CH2 II CH3 CH3 III IV V I II III IV V A Topic: The Aldol Reaction/Condensation (Explicitly Identified) 52. What final product is obtained when 2,8-nonanone is treated with base, followed by reaction with sodium borohydride? OH OH O I III II OH O IV A) B) C) D) E) Ans: V I II III IV V A 644 Chapter 17 Topic: Chemical Tests 53. Which reagent would best serve as the basis for a simple chemical test to distinguish between 2-pentanone and 3-pentanone? A) NaOI (I2 in NaOH) B) Br2/CCl4 C) CrO3/H2SO4 D) NaHCO3/H2O E) Ag(NH3)2+ Ans: A Topic: Chemical Tests 54. Which reagent would best serve as the basis for a simple chemical test to distinguish between CH3CHO and CH3COCH3? A) NaOI (I2 in NaOH) B) Br2/CCl4 C) C6H5NHNH2 D) NaHCO3/H2O E) Ag(NH3)2+ Ans: E Topic: Chemical Tests 55. Which reagent would best serve as the basis for a simple chemical test to distinguish between O C A) B) C) D) E) Ans: O CH3 C and CH3 ? NaOI (I2 in NaOH) Br2/CCl4 CrO3/H2SO4 NaHCO3/H2O Ag(NH3)2+ B 645 Chapter 17 Topic: Chemical Tests 56. Which of the reagents listed below would serve as the basis for a simple chemical test to distinguish between 2-methyl-1-propanol and 2-butanol? A) NaOI (I2 in NaOH) B) KMnO4 in H2O C) Br2 in CCl4 D) Cold concd H2SO4 E) CrO3 in H2SO4 Ans: A Topic: Chemical Tests 57. A compound, C5H10O, reacts with phenylhydrazine and gives a positive iodoform test. The compound could be which of these? H A) B) CH3CH2CH2CH2C=O H CH3CHCH2C=O CH3 C) D) CH2=CHCH2CHOHCH3 O CH3CHCCH3 CH3 O E) CH3CH2CCH2CH3 Ans: D Topic: Chemical Tests 58. A negative iodoform test will be observed in the case of which of these? A) Acetone B) Ethanal C) Ethanol D) 2-Butanol E) All of these will give a positive test. Ans: E 646 Chapter 17 Topic: Tautomerization and Keto-Enol Equilibrium 59. Which of the following represent tautomers? A) CH3CH=CH O and CH3CH CH=O B) CH3 CH=CH2 and CH3 C CH2 O C) CH3 O CH=CH2 O and CH3 C CH3 O H D) All of these E) None of these Ans: C Topic: Tautomerization and Keto-Enol Equilibrium 60. Which of these compounds would exist in an enol form to the greatest extent? O A) B) CH3COC2H5 O O C) CH3CCH2CCH3 O D) CH3CCH3 CH3CH E) O CH3CCH2CH2CCH3 O O Ans: B 647 Chapter 17 Topic: Tautomerization and Keto-Enol Equilibrium 61. Which of the following is a keto-enol tautomeric pair? O OH and O OH and O and OH OH I II O and III OH O IV A) B) C) D) E) Ans: OH and V I II III IV V B Topic: Tautomerization and Keto-Enol Equilibrium 62. Which of the following would undergo racemization in base? CH3 O C CC6H5 O CH3CH2 C6H5CC6H5 CH3CH2CH2 I CH3CH2 II H O C CC6H5 CH3 CH3 O C CCH2C6H5 CH3 III A) B) C) D) E) Ans: CH3 IV I II III IV Both III and IV C 648 Chapter 17 Topic: Tautomerization and Keto-Enol Equilibrium 63. Which of the following would undergo racemization in base? O O H3C I A) B) C) D) E) Ans: O CH3 H3C H H3C II CH3 III O O H H IV V I II and III IV and V I and V I, IV and V D Topic: Tautomerization and Keto-Enol Equilibrium 64. Which of the following would not undergo racemization in base? A) (R)-3-methyl-4-heptanone B) (R)-3-methyl-2-heptanone C) (R)-4-methyl-2-heptanone D) (R)-2,4-dimethyl-3-heptanone E) All of the above will undergo racemization in base Ans: C Topic: Tautomerization and Keto-Enol Equilibrium 65. Which of the following would not undergo racemization in base? A) (S)-2-phenylbutanal B) (S)-3-phenylbutanal C) (S)-3-phenyl-2-butanone D) (S)-3-methyl-2-phenylbutanal E) All of the above will undergo racemization in base Ans: C 649 Chapter 17 Topic: Tautomerization and Keto-Enol Equilibrium 66. Which of the following represent keto-enol tautomers? O OH A) B) CH3CCH2CH3 OH C) CH2=CCH2CH3 O and HOCH2CCH=CH2 CH3C=CHCH3 O and and D) More than one of these E) None of these Ans: D CH3CCH2CH3 O CH3CCH2CH3 Topic: Tautomerization and Keto-Enol Equilibrium 67. Simple enols are less stable than the tautomeric keto forms because: A) severe angle strain exists in the enol forms. B) fewer atoms are coplanar in the keto form. C) the enol cannot be chiral. D) the C-C π bond is weaker than the C-O π bond. E) Actually, simple enols are the more stable. Ans: D 650 Chapter 17 Topic: Tautomerization and Keto-Enol Equilibrium 68. Which would be formed when 2-methylpropanal is dissolved in D2O containing NaOD? O A) CH3CHCD CH3 O B) CH3CHCH CH2D O C) CH3CDCH CH3 O D) CH3CDCD CH3 D E) CH3CHCHOD CH3 Ans: C 651 Chapter 17 Topic: Reagents, Intermediates, and Spectroscopy 69. A compound, X, C9H10O, which reacts with I2/NaOH to give a pale yellow precipitate, gives the following 1H NMR spectrum. δ 2.0 δ 3.0 δ 7.7 Singlet, Singlet, Multiplet, Which is a possible structure for X? O O O I II III O O IV A) B) C) D) E) Ans: V I II III IV V B 652 Chapter 17 Topic: Reagents, Intermediates, and Spectroscopy 70. What is the missing reagent? OH- ? heat O A) O O B) CH3CCH2CH2CCH3 O O C) CH3CCH2CH2CH2CH O O D) CH3CCH2CH2CH2CH2CH O O E) CH3CCH2CH2CH2COEt H O O=CCH2CH2CH2CH2COEt Ans: B Topic: Reagents, Intermediates, and Spectroscopy O O 71. The conversion of C6H5CCH3 oxidizing agent? A) Ag(NH3)2+ B) O3 C) NaOI (I2 in NaOH) O D) to C6H5COH is accomplished by the use of which RCOOH E) Cu++ Ans: C Use the following to answer questions 72-73: H O A OH-,warm (-H2O) B (C11H12O) H2/Ni high pressure 653 OH Chapter 17 Topic: Reagents, Intermediates, and Spectroscopy 72. Consider the synthesis above in answering this question. What is compound A? A) Butanone B) Butanal C) Propanal D) 1-Butanol E) 2-Methylpropanal Ans: B Topic: Reagents, Intermediates, and Spectroscopy 73. What is the intermediate B in the synthesis shown above? OH I A) B) C) D) E) Ans: OH O II III O IV O V I II III IV V D Topic: Reagents, Intermediates, and Spectroscopy 74. Which of these would not be an intermediate or final product when C6H5CH2CN and HCHO react in basic solution and the product is treated with acid? CH2OH A) B) C6H5CHCN CH2 C) C6H5CCN C6H5CHCN D) C6H5CH2C=NH C6H5CHCN C6H5CH2C=O E) Each of these would be either an intermediate or a final product. Ans: E 654 Chapter 17 Topic: Reagents, Intermediates, and Spectroscopy 75. The Robinson annulation reaction which produces CH3 O uses which of the following as starting materials? CH3 H O CH3 + CH2=CHC=O CH2=CHCCH3 CH2 I + CH2 O II O III O O + + CH3CH=CHCCH3 O O CH3CH=CHCCH3 IV A) B) C) D) E) Ans: CH3 CH=CH2 HCHO + V I II III IV V B Topic: Reagents, Intermediates, and Spectroscopy 76. Which compound could be subjected to a haloform reaction to produce m-chlorobenzoic acid? CH2OH CO2H Cl I A) B) C) D) E) Ans: O O CCH2CH3 CCH3 Cl II III I II III IV V D 655 CH2Cl Cl Cl IV V Chapter 17 SHORT ANSWER QUESTIONS Topic: General, Active Hydrogens 77. The α-hydrogens on carbonyl carbons are unusually acidic (pKa 19-20) because: _____________. Ans: the corresponding anion is resonance-stabilized by the carbonyl Topic: Keto-Enol Tautomerism 78. The keto and enol forms of carbonyl compounds are a special type of __________ isomer called ___________. Ans: constitutional; tautomers Topic: Keto-Enol Tautomerism 79. The interconversion of the keto and enol forms of a carbonyl compound is called _____________. Ans: tautomerization Topic: Epimers 80. Diastereomers that differ in configuration at only one stereogenic center are sometimes called ___________, and their interconversion is called __________. Ans: epimers; epimerization Topic: General 81. Dissolving a halogen in aqueous sodium hydroxide provides a solution of _____________. Ans: sodium hypohalite, NaOX Topic: Haloform Reaction 82. The haloform reaction is an efficient method for converting methyl ketones to ____________. Ans: carboxylic acids Topic: General 83. The initial product of the aldol reaction is a β-hydroxycarbonyl compound. These dehydrate readily when heated because the product _______________. Ans: is stabilized by having conjugated double bonds 656 Chapter 17 Topic: Aldol Reaction 84. An aldol reaction that starts with two different carbonyl compounds is called a _______________. Ans: crossed aldol reaction Topic: Kinetic/Thermodynamic Enolates 85. An unsymmetrical ketone can form two possible enolates. The enolate with the more highly substituted double bond is called the ____________. Ans: thermodynamic enolate Topic: Kinetic/Thermodynamic Enolates 86. The kinetic enolate (the less highly substituted double bond) is favored when __________ is used as a base. Ans: LDA or lithium diisopropylamide Topic: 1,2- /1,4- Addition 87. When α,β-unsaturated aldehydes and ketones react with nucleophiles, they do so in one of two ways. What are the two ways? Ans: simple or 1,2-addition; conjugate or 1,4-addition Topic: Kinetic/Thermodynamic Enolates 88. When α,β-unsaturated aldehydes and ketones react with nucleophiles, simple addition is favored when _________ nucleophiles are used, while conjugate addition is preferred by ___________ nucleophiles. Ans: strong; weaker Topic: Kinetic/Thermodynamic Enolates 89. The sequence of a Michael addition followed by an intramolecular aldol condensation is known as a ___________. Ans: Robinson annulation 657 Chapter 17 Topic: 1,2- /1,4- Addition 90. When 5-methyl-3-hepten-2-one reacts with CH3Cu, the major product expected is___________ (structure and IUPAC name). Ans: The 1,4-addition product: O 4,5-dimethyl-2-heptanone Topic: Reaction Products: Stereochemical Outcomes 91. When optically active 2-methyl-1-phenyl-1-butanone undergoes reaction with Br2/H3O+, the product is observed to exhibit no optical activity. Explain clearly. Ans: An achiral enol is formed in presence of H3O+, which can then undergo reaction with Br2 from both faces, to produce a racemic mixture of the brominated product; hence, no observed optical activity. The reaction with (R)-2-methyl-1-phenyl-1butanone is shown below; the same enol and products can be formed from the (S) enantiomer. O H CH3 H3O+ + OH OH CH3 H CH3 achiral enol Br2 O Br CH3 (S) 658 O + Br CH3 (R) Chapter 17 Topic: Multistep Reaction Sequence: 92. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. O O O i. Zn, Br ? ii. H3O+, heat iii. DIBAL-H iv. H2O v. (CH3)2CuLi vi. H2O O Ans: O O O i. Zn, Br O ii. H3O+, heat i. DIBAL-H ii. H2O i. (CH3)2CuLi ii. H2O O O Topic: Multistep Reaction Sequence: 93. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. CN O i. , EtO-, EtOH ? + ii.H3O , heat Ans: O CN + - CN EtO , EtOH 659 H3O heat CO2H Chapter 17 Topic: Multistep Reaction Sequence: 94. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. i. Cl2, FeCl3 O ? NO2 , EtO-, EtOH ii. iii.H3O+ OH Ans: O Cl2, FeCl3 O NO2 i. EtO-, EtOH ii. H3O+ Cl NO2 Cl Topic: Synthetic Strategy 95. Suggest a reasonable synthetic strategy to carry out the following transformation. O OH Br OCH3 Ans: O Br2, FeBr3 O i. O - EtO , EtOH ii. H3O+, heat Br O OCH3 Br i. LAH ii. H2O OH Br 660 Chapter 17 Topic: Multistep Reaction Sequence 96. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. O O i. EtO-, EtOH ? ii. CH3CH2NH2 Ans: O EtO-, EtOH H N CH3CH2NH2 O O O Topic: Reaction Products 97. There are several possible cyclization products that might be formed when 5-methyl-6oxoheptanal undergoes intramolecular aldol condensation in presence of ethoxide. Draw the structures of all these possible products. Comment on which of these is likely to be the major product, clearly explaining your rationale. Ans: There are 3 possible products (I-III) that might be formed from the 3 theoretically possible enolates. The rationale for predicting the major product is the following: i) aldehydes are typically more reactive toward nucleophilic addition than ketones, so I and III are more likely than II; ii) since 5-membered rings are formed much more readily than 7-membered rings, I is more likely than III. - EtO , EtOH O O O O HO Topic: Reaction Products 98. What is the product of the following reaction? O OH- O O Ans: ? OH- O O 661 HO HO I major product O II III Chapter 17 Topic: Reaction Products 99. What is the product of the following reaction? O i. LDA, THF ii. O O Ans: ? O i. LDA, THF ii. O OH Topic: Multistep Reaction Sequence 100. What is the product of the following reaction sequence? Give structural details of all significant intermediates. O O Ans: i. OHii. heat O ? OH- O heat O O 662 Chapter 18 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. Which of the following is the best name for the following compound? O O A) B) C) Isobutyl ethanoate Ethyl isopropanoate 3-methylbutyl ethanoate D) Ethoxy isobutyl ketone E) Ethyl 3-methylbutanoate Ans: C Topic: Nomenclature O 2. O A correct name for A) 2-Methylbutyl 2-methylbutanoate B) 2-Methylbutyl 3-methylbutanoate C) 3-Methylbutyl isovalerate D) Isopentyl isovalerate E) Isopentyl isobutyrate Ans: B is: Topic: Nomenclature Cl 3. Cl What is the IUPAC name for A) B) C) D) E) Ans: O ∝-Chlorovaleryl chloride 2-Chloropentanoyl chloride 1-Chloropentanoyl chloride 1,2-Dichloropentanal 1-Chloro-1-butanecarbonyl chloride B 663 Chapter 18 Topic: Nomenclature 4. O O What is the IUPAC name for 2,3−dimethylbutyl acetate 2,3−dimethyl-4-oxoethanal 2,3−dimethylbutyl methanoate 2,3−dimethylbutyl methylate 2,3−dimethylbutyl formylate C A) B) C) D) E) Ans: Topic: Nomenclature 5. Which of the following structures is 3,4-dimethylpentyl chloroformate? H Cl O O Cl O Cl I O III Cl Cl IV O O II O A) B) C) D) E) O O O V I II III IV V Ans: E 664 Chapter 18 Topic: Nomenclature 6. Which of the following structures is N-benzyl-N-propyl-2,3-dimethylbutanamide? H N N N O O O I II III N N O O IV A) B) C) D) E) Ans: V I II III IV V E Topic: Acidity 7. In which of the following sequences are acidity? A) CH3COOH > H2O > CH3CH2OH B) CH3CH2OH > CH3COOH > H2O C) CH3COOH > CH3CH2OH > H2O D) H2O > CH3COOH > CH3CH2OH E) CH3CH2OH > H2O > CH3COOH Ans: A 665 the compounds listed in order of decreasing > > > > > HC≡CH > NH3 HC≡CH > NH3 NH3 > HC≡CH HC≡CH > NH3 HC≡CH > NH3 Chapter 18 Topic: Acidity 8. Which compound would be the strongest acid? A) CHCl2CH2CH2CO2H B) ClCH2CHClCH2CO2H C) CH3CCl2CH2CO2H D) CH3CHClCHClCO2H E) CH3CH2CCl2CO2H Ans: E Topic: Acidity 9. Which of the following would be the strongest acid? Cl CO2H CO2H CO2H Cl I Cl II III CO2H Cl IV A) B) C) D) E) Ans: Cl CO2H Cl Cl V I II III IV V C Topic: Acidity 10. Which of the following acids would have the smallest value for pKa? A) BrCH2CH2CH2COOH B) ClCH2CH2CH2COOH C) Cl2CHCH2CH2COOH D) ICHBrCH2CH2COOH E) BrCCl2CH2CH2COOH Ans: E 666 Chapter 18 Topic: Acidity 11. Which compound would be most acidic? Acetone A) Acetic acid B) Ethanol C) D) E) Ans: Phenol Acetone Water A Topic: Acidity 12. In which of the following are the compounds listed in order of decreasing acidity? A) CH3CO2H > CH3CH2OH > C6H5OH > H2O B) C6H5OH > CH3CO2H > H2O > CH3CH2OH C) CH3CO2H > H2O > C6H5OH > CH3CH2OH D) H2O > CH3CO2H > C6H5OH > CH3CH2OH E) None of the above Ans: E Topic: Acidity 13. Which of the following would be the strongest acid? A) Benzoic acid B) 4-Nitrobenzoic acid C) 4-Methylbenzoic acid D) 4-Methoxybenzoic acid E) 4-Iodobenzoic acid Ans: B 667 Chapter 18 Topic: Acidity 14. Which of the following would be the strongest acid? A) B) C) 2,3-dimethylhexanoic acid 3,3-diiodopentanoic acid 3-iodo-4-bromopentanoic acid D) 3-chloro-4-bromohexanoic acid E) 2-fluoro-4-bromopentanoic acid Ans: E Topic: Acidity 15. A 0.2505 g sample of an organic acid is titrated to the stoichiometric endpoint with 20.10 mL of 0.0750 M NaOH. Which of these is a possible structure for the acid? A) C6H5CO2H B) p-CH3C6H4CO2H C) m-ClC6H4CO2H D) o-NO2C6H4CO2H E) p-BrC6H4CO2H Ans: D Topic: Chemical Tests, Relative Reactivities, and Physical Properties 16. Which reagent would serve as the basis for a simple chemical test to distinguish between benzoic acid and benzamide? A) Cold dilute NaOH B) Cold dilute NaHCO3 C) Cold concd H2SO4 D) More than one of these E) None of these Ans: D 668 Chapter 18 Topic: Chemical Tests, Relative Reactivities, and Physical Properties 17. Which reagent would best serve as a basis for a simple chemical test to distinguish between CH3CH2COOH and CH3COOCH3? A) Concd H2SO4 B) Br2/CCl4 C) CrO3/H2SO4 D) NaHCO3/H2O E) KMnO4/H2O Ans: D Topic: Chemical Tests, Relative Reactivities, and Physical Properties 18. Which reagent would best serve as the basis for a simple chemical test to distinguish between C6H5CH=CHCOOH and C6H5CH=CHCH3? A) Concd. H2SO4 B) Br2/CCl4 C) CrO3/H2SO4 D) NaHCO3/H2O E) KMnO4/H2O Ans: D Topic: Chemical Tests, Relative Reactivities, and Physical Properties 19. Which compound would be most reactive toward nucleophilic acyl substitution? (CH3CO)2O A) CH3CO2Na B) CH3COCl C) (CH3CO)2O D) (CH3CONH2 E) CH3CO2CH3 Ans: B 669 Chapter 18 Topic: Chemical Tests, Relative Reactivities, and Physical Properties 20. The relative reactivity of acyl compounds toward nucleophilic substitution is: A) B) C) Amide > ester > acid anhydride > acyl chloride Acyl chloride > ester > acid anhydride > amide Ester > acyl chloride > acid anhydride > amide D) Acyl chloride > acid anhydride > ester > amide E) Acid anhydride > acyl chloride > ester > amide Ans: D Topic: Chemical Tests, Relative Reactivities, and Physical Properties 21. Alkaline hydrolysis of an ester involves initial attack by hydroxide ion on the carbonyl carbon. The presence of substituents on the aromatic ring of ethyl benzoate may be expected to increase/decrease the rate of hydrolysis of this ester. In what order should the five substituents below be arranged to represent the decreasing order of the rates of hydrolysis when these substituents are present in the para- position of the aromatic ring in ethyl benzoate? A) -NO2 > -H > -Cl > -CH3 > -OCH3 B) -NO2 > -Cl > -H > -CH3 > -OCH3 C) -OCH3 > -CH3 > -Cl > -H > -NO2 D) -Cl > -NO2 > -H > -OCH3 > -CH3 E) -H > -Cl > -CH3 > -OCH3 > -NO2 Ans: B Topic: Chemical Tests, Relative Reactivities, and Physical Properties 22. Which of the following will not undergo hydrolysis, whether acid or base is present? A) CH3COCl B) CH3CONH2 C) (CH3CO)2O D) CH3CO2CH2CH3 E) CH3COCH2CH2CH3 Ans: D 670 Chapter 18 Topic: Chemical Tests, Relative Reactivities, and Physical Properties 23. Which of these compounds could not be formed by nucleophilic attack by an appropriate reagent on acetyl chloride? A) CH3CONH2 B) CH3CO2CH2CH3 C) ClCH2COCl D) CH3CO2H E) (CH3CO)2O Ans: C Topic: Chemical Tests, Relative Reactivities, and Physical Properties 24. In which of these species are all the carbon-oxygen bonds of equal length? A) Diethyl carbonate B) Methyl butanoate C) Lithium acetate D) Propionic anhydride E) Pentanoic acid Ans: C Topic: Reaction Products 25. What is the expected product, A, of the following reaction sequence? i. NaCN Cl A + NH4+ ii. 70% H2SO4, reflux A) B) C) D) E) Ans: HCO2CH2C6H5 C6H5CH2COOH C6H5CH2OSO3H C6H5CHClCOOH O=C(CH2C6H5)2 B 671 Chapter 18 Topic: Reaction Products 26. Predict the major organic heat + KMnO4 − H2O, OH product H3O+ of ? OH CO2H OH I CHO II III OH CHO IV A) B) C) V I II III D) IV E) V Ans: B 672 the reaction sequence below: Chapter 18 Topic: Reaction Products 27. What would be the product of the following reaction ? 18 HA OH O ? + H O 18O 18O O O 18O I II O 18 O III O 18 O O O II III \ A) I B) C) D) E) Ans: II III IV V A Topic: Reaction Products 28. What would be the final product, F, of the following sequence of reactions? i. Mg, Et2O PBr3 i. LAH, Et2O F CO2H ii. H O 2 ii. CO2 iii. H3O+ Br I A) B) C) D) E) Ans: CO2H CO2H Br O CO2H O II IV III I II III IV V D 673 V Chapter 18 Topic: Reaction Products 29. The product, Z, of the following sequence of reactions is which compound? − i. KMnO4, OH , heat p-Chlorotoluene ii. H3O+ Z iii. SOCl2 iv. CH3CH2OH, base O O O O Cl Cl I II III O O Cl Cl Cl IV A) B) I II C) D) E) III IV V V Ans: B 674 Chapter 18 Topic: Reaction Products 30. Predict the major organic product, P, of the following sequence of reactions: i. OH− (2eq.), H2O heat Cl CO2H ii. H O+ 3 Cl H2 cat. i. SOCl2 ii. CH3OH O O O CO2H O I O II III Cl O O O O IV A) B) C) D) E) Ans: P V I II III IV V D 675 Chapter 18 Topic: Reaction Products 31. Predict the major organic product of the reaction sequence, O i. NH3, H2O O O M ii. dilute HCl, cold O O OH HO O NH2 HO O O I O II O H N O III HN IV A) B) C) D) E) Ans: NH2 H2N O O V I II III IV V B Topic: Reaction Products 32. (R)-3-hexanol is subjected to the following sequence of reactions: i) acetyl chloride, pyridine; ii) NaOH(aq), heat. What is(are) the likely final product(s)? A) (R)-3-hexanol B) (S)-2-hexanol C) Equal amounts of A) and B) D) 2-Hexene (cis and trans) E) 1-Hexen-2-ol Ans: A 676 Chapter 18 Topic: Reaction Products 33. What would be the final product? C6H5CH2CONH2 A) B) C) D) E) Ans: P4H10 heat i. CH3MgI, Et2O ii. H3O+ ? C6H5CH2CO2CH3 C6H5CH2CH2NHCH3 C6H5CH2COCH3 C6H5CH2CH(CH3)CN C6H5CH2CH=NCH3 C Topic: Reaction Products 34. Predict the final product likely to be obtained when (S)-2-methyl-3-pentanol is subjected to the following sequence of reactions: i) benzoyl chloride; ii) NaOH (aq), heat A) (S)-2-methyl-3-pentanol B) (R)-2-methyl-3-pentanol C) (R,S)-2-methyl-3-pentanol D) 2-methyl-2-pentene E) (R,S)-2-methyl-3-pentanol and 2-methyl-2-pentene in more or less equal amounts Ans: A Topic: Reaction Products 35. Predict the final product likely to be obtained when (S)-2-methyl-3-pentanol is subjected to the following sequence of reactions: i) Tosyl chloride; ii) NaOH (aq), heat A) (S)-2-methyl-3-pentanol B) (R)-2-methyl-3-pentanol C) (R,S)-2-methyl-3-pentanol D) 2-methyl-2-pentene E) (R,S)-2-methyl-3-pentanol and 2-methyl-2-pentene in more or less equal amounts Ans: B 677 Chapter 18 Topic: Reaction Products 36. The product of the following reaction is: O heat OH + O ? O (1 mol) (1 mol) O O O O O OH O CO2H CO2H II I O III O O O Cl O Cl O O H O IV A) B) C) D) E) Ans: V I II III IV V A Topic: Reaction Products 37. What final product, Q, would be obtained via the following reaction sequence? O H3C H H OH C6H5 Cl OH−/ H2O pyridine heat A) cis-3-Methylcyclopentanol B) C) D) E) Ans: trans-3-Methylcyclopentanol Equal amounts of A) and B) 3-Methylcyclopentanone None of these B O Q + C6H5 678 O Chapter 18 Topic: Reaction Products 38. What would be the final organic product of the following reaction? NaCN C6H5 Cl i. excess LAH, Et2O ii. H2O ? A) C6H5CH2CH2CO2H B) C6H5CH2CH2NH2 C6H5CH2CH(CH3)CN C) C6H5CH2CH(CH3)CN D) C6H5CH2CH=NH E) C6H5CH2NH2 Ans: B Topic: Reaction Products 39. What would be the final organic product of the following reaction? i. Mg, Et2O Br ii. CO2 i. LAH, Et2O ii. H2O iii. H3O+ A) B) C) D) E) Ans: (CH3)3CCO2H (CH3)3CCOCH3 (CH3)3CCH2OH (CH3)3COCH3 (CH3)3CCO2CH3 C 679 ? Chapter 18 Topic: Reaction Products 40. Identify the product(s) of the following reaction. O heat CO2H ? O O O O OH I II CO2H + CO IV A) B) I II C) D) E) Ans: III IV V C III 2 CO2H V Topic: Reaction Products 41. What would be the final product? i. PCl5 CO2H ? ii. NH3 iii. P4H10, heat A) B) C) D) E) Ans: + CO2 O CH3CH2CH2NH2 CH3CH2CONH2 CH3CH2CONHCOCH2CH3 CH3CH2CN CH3CH2COO-NH4+ D 680 Chapter 18 Topic: Reaction Products 42. What is the final product of this sequence of reactions? i. Mg, Et2O Br i. SOCl2 ii. excess NH3 ii. CO2 ? + iii. H3O O NH2 NH2 CN O I O II III NHCl NH2 O IV A) B) C) V I II III D) IV E) V Ans: C 681 Chapter 18 Topic: Reaction Products 43. What is the product of the reaction of 1-propanol with phenyl isocyanate, C6H5N=C=O? H A) N O C6H5 O CO2H B) C6H5 N CHO C) C6H5 D) C6H5 N O H N O O E) C6H5 H N O Ans: A Topic: Reaction Products 44. What would be the final product of this reaction sequence? CO2H i. PCl3 ? ii. NH3 iii. P4O10 O CN NH2 NH2 II I CO2 NH4 III H N H N O IV A) B) C) D) E) Ans: V I II III IV V A 682 Chapter 18 Topic: Reaction Products 45. What is the ultimate O Cl O O H N N H H N of this sequence CH3CH2OH (1 eq.) CH3NH2 O O Cl N H O I A) B) C) D) E) Ans: Cl product II O O O V Topic: Reaction Products 46. What is the product of this reaction? O CH3OH ? O O HO CO2H O O I II O O III HO O O O O O IV A) B) C) D) E) Ans: O V I II III IV V B 683 Cl O I II III IV V A O reactions? ? IV III of Chapter 18 Topic: Reaction Products 47. What is the product of the reaction of propanamide with methylmagnesium bromide (1 eq.)? O A) N H O B) N O C) O D) NHMgBr + CH4 O E) H2N OMgBr Ans: D Topic: Reaction Products 48. What is the final product obtained when toluene is subjected to the following reaction sequence? i) Cl2 (large excess), heat, hν; ii) OH−/H2O, heat; iii) H3O+ OH OH OH CO2H CCl3 HO I II III Cl HO CCl3 OH Cl IV A) B) C) D) E) Ans: Cl V I II III IV V B 684 Chapter 18 Topic: Structure Identification (Spectroscopy) 49. A compound has the molecular formula, C6H12O2. Its IR spectrum shows a strong absorption band near 1740 cm-1; its 1H NMR spectrum consists of two singlets, at δ 1.4 and δ 2.0. The most likely structure for this compound is: O O O O O O I II III O O IV A) B) C) D) E) Ans: O O V I II III IV V D 685 H Chapter 18 Topic: Structure Identification (Spectroscopy) 50. A compound has the molecular formula C8H14O4. Its IR spectrum shows a strong absorption band near 1740 cm-1. Its 1H NMR spectrum consists of: δ 1.3 δ 2.6 δ 4.2 triplet, singlet, quartet, The most likely structure for the compound is: O O O O O O I O O O O O O II III O HO2C CO2H O O O IV A) B) C) D) E) Ans: V I II III IV V A 686 Chapter 18 Topic: Structure Identification (Spectroscopy) 51. A compound with the molecular formula C5H10O2 gave the following 1H NMR spectrum: triplet, multiplet, singlet, triplet, δ 0.90 δ 1.60 δ 1.95 δ 3.95 The IR spectrum showed a strong absorption band near 1740 cm-1. The most likely structure for the compound is: O A) O O B) O O C) O D) H O O O E) HO Ans: A 687 Chapter 18 Topic: Structure Identification (Spectroscopy) 52. A compound with the molecular formula C18H18O4 has a 1H NMR spectrum that consists of: δ 2.7 δ 3.1 δ 7.3 singlet, singlet, multiplet, The IR spectrum shows a strong absorption band near 1750 cm-1. The most likely structure for the compound is: O A) O C H C6H5 O 6 5 O O B) C6H5 O O O C6H5 O C) C6H5 O O C6H5 O O D) C6H5 O O C6H5 O O E) C6H5 O O C6H5 O Ans: C Topic: Structure Identification (Spectroscopy) 53. The IR spectrum of a compound exhibits a broad absorption band at 2500-3000 cm-1 and a sharp band at 1710 cm-1. Which of these compounds could it be? A) 1-Butanol B) Propyl acetate C) Butanoic acid D) Acetyl chloride E) Acetic anhydride Ans: C 688 Chapter 18 Topic: Synthesis 54. Which of the following reactions would constitute a reasonable synthesis of propyl acetate? OH HA A) + OH O B) C) OH + OH + pyridine Cl O O O O D) All of these E) None of these Ans: D Topic: Synthesis 55. Which of the following would serve as a synthesis of 2,2-dimethylpropanoic acid? A) Br i. Mg, Et2O ii. CO2 B) C) iii. H3O+ OH i. KMnO4, OH−, heat Br ii. H3O+ i. CN− ii. OH−, H2O, heat iii. H3O+ D) All of these E) Answers A) and B) only Ans: E 689 Chapter 18 Topic: Synthesis 56. Which of the reactions listed below would serve as a synthesis of acetophenone, C6H5COCH3 ? O A) C6H5 + (CH3)2CuLi Cl O B) H3C C) Cl O AlCl3 + C6H6 + CH3MgI OCH3 C6H5 D) Two of these E) All of these Ans: D Topic: Synthesis 57. Which of the following would serve as syntheses of (CH3)3CCO2H? O i. Cl2/OH− (excess) A) ii. H3O+ − i. CN B) Br C) Br + ii. H3O (heat) i. Mg, Et2O ii. CO2 iii. H3O+ D) Answers A) and B) only E) Answers A) and C) only Ans: E 690 Chapter 18 Topic: Synthesis 58. Which of the reactions listed below would serve as a synthesis of benzyl acetate, CH3CO2CH2C6H5 ? Benzyl alcohol + acetic anhydride Æ A) Benzyl alcohol + acetic anhydride Æ B) Benzyl alcohol + acetic acid + H3O+ Æ C) Benzyl alcohol + acetyl chloride Æ D) Answers A) and C) only E) Answers A), B), and C) Ans: E Topic: Synthesis 59. Which reactant is unlikely to produce the indicated product upon strong heating? A) 2,2-dimethylpropanedioic acid Æ 2-methylpropanoic acid B) 2-ethylpropanedioic acid Æ Butanoic acid C) 2-methyl-3-oxo-pentanoic acid Æ 3-Pentanone D) 2-methyl-4-oxo-pentanoic acid Æ 2-Methyl-3-butanone E) 4-methyl-3-oxo-heptanoic acid Æ 3-Methyl-2-hexanone Ans: D Topic: Synthesis 60. N,N-Dimethylbenzamide can be made from which of the following? + N A) C6H5 O H O B) Cl C6H5 + O C) C6H5 D) C6H5 O O O O NH2 C6H5 N H + N H + CH3MgCl E) A), B), and C) only Ans: E 691 Chapter 18 Topic: Synthesis 61. Choose the reagent(s) that would bring about the following reaction: CH3CH2CH2COOH ⎯⎯⎯→ CH3CH2CH2CH2OH A) H2/Ni B) Li/liq NH3 C) LiAlH[OC(CH3)3]3 D) NaBH4, CH3OH E) LiAlH4, ether Ans: E Topic: Synthesis 62. Choose the reagent(s) that would bring about the following reaction: CH3CH2CH2CO2CH3 ⎯⎯⎯→ CH3CH2CH2CHO A) H2/Ni B) Li/liq NH3 C) LiAlH[OC(CH3)3]3 D) NaBH4, CH3OH E) LiAlH4, ether Ans: C Topic: Synthesis 63. Choose the reagent(s) that would bring about the following reaction: CH3C≡CCO2CH3 ⎯⎯⎯→ (E)-CH3CH=CHCO2CH3 A) H2/Ni B) Li/liq NH3 C) LiAlH[OC(CH3)3]3 D) NaBH4, CH3OH E) LiAlH4, ether Ans: B 692 Chapter 18 Topic: Synthesis 64. Choose the reagent(s) that would bring about the following reaction: CH3C≡CCH2CO2CH2CH3 ⎯⎯⎯→ CH3CH≡CHCH2CH2OH A) H2/Ni B) Li/liq NH3 C) LiAlH[OC(CH3)3]3 D) NaBH4, CH3OH E) LiAlH4, ether Ans: E Topic: Synthesis 65. Which of the following compounds is capable of forming a δ-lactone? A) 5-hydroxypentanoic acid B) Pentanedioic acid C) 4-hydroxypentanoic acid D) 3-hydroxypentanoic acid E) 2-hydroxypentanoic acid Ans: A Topic: Synthesis 66. Which of the following reactions could be used to synthesize ethyl acetate? A) B) C) D) E) Ans: CH3CH2OH + (CH3CO)2O + pyridine ⎯⎯⎯→ CH3CH2OH + (CH3CO)2O ⎯⎯⎯→ CH3CH2OH + CH3CO2H + H3O+ ⎯⎯⎯→ Answers A) and C) only Answers A), B), and C) E 693 Chapter 18 Topic: Synthesis 67. Which of the following would yield (S)-2-butanol? i. CH3CO2−Na+ A) (R)-2-Bromobutane − ii. OH , H2O, heat − B) (R)-2-Bromobutane C) (S)-sec-Butyl acetate OH , H2O, heat OH−, H2O, heat D) All of these E) None of these Ans: D Topic: Synthesis 68. Which of the following would serve as a reasonable synthesis of ethyl benzoate? OH HA A) C6H5 OH + reflux O excess Cl C6H5 B) base OH + O C) C6H5 O C6H5 O O + OH D) All of the above E) None of the above Ans: D Topic: Synthesis 69. On theoretical grounds, one would predict that the (1:1) reaction of acetic propionic anhydride with methyl alcohol would form chiefly: A) Methyl acetate + propionic acid B) Acetone + propionic acid C) Methyl propionate + acetic acid D) Methyl acetate + acetic acid E) Methyl ethyl ketone + acetic acid Ans: A 694 Chapter 18 Topic: Synthesis 70. Which of the following combinations of reagents would not produce an ester? OAg A) H3C Br + O B) ONa H3C C) H3C D) H3C E) H3C OH + O OH O CH3 O O O HA OH + + OH Cl O + OH Ans: B Topic: Synthesis 71. Which carboxylic acid would decarboxylate when heated to 100-150°C? CO2H HO2C I A) B) C) D) E) Ans: O CO2H II CO2H HO2C III I II III More than one of these None of these D Topic: Methods and Miscellaneous 72. An acid chloride is prepared from the related carboxylic acid by reaction with which of these? A) HCl B) Cl2 C) SOCl2 D) HOCl E) AlCl3 Ans: C 695 Chapter 18 Topic: Methods and Miscellaneous 73. Which of the following is not a method for preparing butanoic acid? A) CH3CH2CH2Br + NaCN; then H3O+, reflux B) CH3CH2CH2MgBr + CO2; then H3O+ C) CH3CH2CH2OH + CO D) CH3CH2CH2CO2Et + OH−/H2O; then H3O+ E) CH3CH2CH2CH2OH + KMnO4/OH−/H2O/heat; then H3O+ Ans: C Topic: Methods and Miscellaneous 74. Intramolecular dehydration to form a cyclic monoester is most likely to occur when which of the following is heated with acid? A) CH3CH2CH2CHOHCO2H B) CH3CH2CHOHCH2CO2H C) CH3CH2CH2CH2CO2H D) CH3CHOHCH2CH2CO2H E) HO2CCH2CH2CO2H Ans: D Topic: Methods and Miscellaneous 75. Which of these combinations will not produce benzoic acid? A) C6H5CH2OH + KMnO4/OH−/H2O, heat; then H3O+ B) C6H5CH3 + KMnO4/OH−/H2O, heat; then H3O+ C) C6H6 + CO2, high pressure D) C6H5COCH3 + Cl2/OH−/H2O; then H3O+ E) C6H5COCl + OH−/H2O; then H3O+ Ans: C 696 Chapter 18 Topic: Methods and Miscellaneous 76. Reasoning by analogy, one would predict that the reaction of carbon disulfide with secbutylmagnesium bromide should yield which of the following (after acidification)? S S SH SH SH III II I S S SH IV A) B) C) D) E) Ans: V I II III IV V A Topic: Methods and Miscellaneous 77. γ - And δ-hydroxy acids can be esterified intramolecularly to form compounds known as which of these? A) Anhydrides B) Cycloalkenes C) Lactones D) Lactams E) Cyclic ketones Ans: C 697 Chapter 18 Topic: Methods and Miscellaneous 78. Which of the following statements concerning nitriles is incorrect? A) Nitriles can be hydrolyzed to carboxylic acids. B) Nitriles can be formed from (many) alkyl halides by nucleophilic substitution by cyanide ion. C) Nitriles can be reduced with excess lithium aluminum hydride to primary amines, RNH2. D) Nitriles react with Grignard reagents to form tertiary alcohols. E) Nitriles can be made by the dehydration of amides. Ans: D SHORT ANSWER QUESTIONS Topic: Nomenclature 79. While the IUPAC name for HCO2H is methanoic acid, it is commonly known as __________. Ans: formic acid Topic: Nomenclature 80. Ethanoic acid (CH3CO2H) is usually called _______________, from the Latin for “vinegar”. Ans: acetic acid Topic: Reaction Mechanisms 81. Acyl compounds tend to react by acyl substitution mechanisms because they all have a good or reasonably good ________________ attached to the carbonyl carbon. Ans: leaving group Topic: Miscellaneous 82. Cyclic esters are called _____________, while cyclic amides are called _________. Ans: lactones; lactams 698 Chapter 18 Topic: Methods and Miscellaneous 83. An acid-catalyzed esterification (a reaction between a carboxylic acid and an alcohol) is called a ________________. Ans: Fischer esterification Topic: Methods and Miscellaneous 84. Base-promoted hydrolysis of esters is sometimes called ______________. Ans: saponification Topic: Methods and Miscellaneous 85. The linkages that join amino acids together to form proteins are primarily ___________ bonds. Ans: amide Topic: Methods and Miscellaneous 86. Litmus paper turns ___________ when an aqueous solution of a carboxylic acid is dropped on it. Ans: red Topic: Miscellaneous 87. The only carboxylic acid derivative with two carbonyl groups is the ___________. Ans: anhydride Topic: Miscellaneous 88. The presence of electron-withdrawing substituents close to the carboxylic acid functional group will ___________ the acidity of the molecule by _________. Ans: increase; induction Topic: Reactions 89. When a cyclic ketone undergoes the Bayer-Villiger oxidation, the product can be described as a ______________. Ans: lactone (cyclic ester) 699 Chapter 18 Topic: Reactions 90. When a gamma-hydroxy acid is treated with dilute acid, cyclization occurs, producing a ______________. Ans: lactone (cyclic ester) Topic: Miscellaneous 91. The functional group in a lactam is _________________. Ans: amide Topic: Nomenclature 92. Draw the structure for 3-methylbutanoic anhydride. O O Ans: O Topic: Nomenclature 93. Draw the structure for 3-ethyl-4,4-dimethylhexanenitrile. Ans: CN Topic: Nomenclature 94. Draw the structure for 3-oxo-5-bromohexanoic acid. OH Ans: Br O O Topic: Nomenclature 95. Draw the structure for 4-methylpentyl 3-ethylpentanoate. O Ans: O 700 Chapter 18 Topic: Reaction Sequence 96. Complete the following reaction sequence, giving details of all significant intermediates. O O i.) 2 equiv CH3Li ii.) CH3I O Ans: ? OLi 2 equiv CH3Li CH3I OCH3 O Topic: Reaction Sequence 97. Complete the following reaction sequence, giving details of all significant intermediates. O i.) SOCl2 ? ii.) CH3CH2CH2NHCH3 OH Ans: O O SOCl2 OH O CH3CH2CH2NHCH3 Cl N Topic: Synthetic Strategy 98. Suggest a suitable synthetic strategy for the transformation of 3-methyl-1-pentanol into propyl 3-methylpentanoate OH i. KMnO , OH-, H O O Ans: 4 2 ii. H3O+ OH SOCl2 O OH O O Cl 701 Chapter 18 Topic: Reaction Sequence 99. Complete the following reaction sequence, giving details of all significant intermediates. i. KMnO4, OH-, H2O ii. H3O+ ? iii. NaBH4, H2O + iv. H3O Ans: i. KMnO4, OH-, H2O ii. H3O+ O O OH NaBH4, H2O + O H3O OH O OH O 702 Chapter 18 Topic: Reaction Sequence, Spectroscopic Analysis 100. When propylbenzene is subjected to the sequence of reactions outlined below, the major product is found to exhibit the following 1H NMR spectrum: d 1.2 ppm, triplet 2.2 ppm, quartet 7.5 ppm, multiplet Account for the formation of this product, giving details of all significant intermediates. i. NBS ii. NaOH iii. CrO3 iv. RCO3H ? Ans: Reaction with NBS would lead to benzylic bromination, followed by nucleophilic substitution to afford the corresponding alcohol. Oxidation with CrO3 would yield an alkyl aryl ketone, which would undergo Bayer-Villiger oxidation with a peroxy acid to afford the ester shown below (along with the likely 1H NMR signal assignment). Br NBS OH NaOH CrO3 2.2 ppm O O RCO3H O 7.5 ppm 1.2 ppm 703 Chapter 18 Topic: Reaction Sequence 101. Complete the following reaction sequence, giving details of all significant intermediates. OH i. COCl2 (1 equivalent) ? ii. CH3CH2CH2CH2NHCH3 Ans: OH O COCl2 (1 equivalent) Cl O H N O N O 704 Chapter 19 MULTIPLE CHOICE QUESTIONS Topic: Relative Acidities 1. Which of the compounds listed below is more acidic than 1-butanol? A) Ethyl acetoacetate B) 2-butanone C) Ethyl pentanoate D) All of these answers E) Answers A) and B) only Ans: A Topic: Relative Acidities 2. Which of the compounds listed below is more acidic than 2-pentanol? A) Ethyl 3-oxopentanoate B) 2-pentanone C) Pentanal D) All of these answers E) Answers A) and B) only Ans: A Topic: Relative Acidities 3. Which of the following hydrogens is the most acidic? O II I A) B) C) D) E) Ans: O I II III IV V C IV III O V O Chapter 19 v Topic: Relative Acidities 4. Which is the most acidic hydrogen in the compound shown? V III II O v v O O v v IV I A) B) C) D) E) Ans: I II III IV V C Topic: Relative Acidities 5. Which of the following compounds is the strongest acid? OH O CN NO2 NO2 O II I O III CN CN CO2Et IV A) B) C) D) E) Ans: I II III IV V E V Chapter 19 Topic: Relative Acidities 6. Which of the indicated hydrogens can be replaced by alkylation? (V) H H H H H (IV) H S S H3C H3C H (I) A) B) C) D) E) Ans: I II III IV V C H (III) (II) Topic: Relative Acidities 7. Which of the indicated hydrogens is most likely to be removed upon treatment with nbutyllithium? (V) H H H H H (IV) H S H3C H3C (I) A) B) C) D) E) Ans: S H (III) H (II) I II III IV V C Chapter 19 Topic: Reaction Products 8. What would be the major product of the following reaction? i. NaOC2H5 O ? + ii. H O 3 O O O O O I O O O O II III O O OH O IV A) B) C) D) E) Ans: I II III IV V C O O O OH V Chapter 19 Topic: Reaction Products 9. What would be the product of the following sequence? O O O + O O i. NaOC2H5, C2H5OH ? ii. H3O+ OH O O O O O O II I III O O O O IV A) B) C) D) E) Ans: I II III IV V A O V O Chapter 19 Topic: Reaction Products 10. What is the expected product from the following reaction sequence? O O O i. NaOC2H5, C2H5OH + ? O O ii. H3O+ O O O O O O O O O O O II I III O O O IV A) B) C) D) E) Ans: O O V I II III IV V A Topic: Reaction Products 11. What is the product, Z, of the following reaction sequence? O H N H3O+ + O O Ph O Ph I Ph III II Ph N O O Ph O IV A) B) C) D) E) Ans: I II III IV V B Z (-H2O) O N H3O+ PhCOCl V Chapter 19 Topic: Reaction Products 12. What would be the product, P, of the following reaction sequence? O O i. NaOH ii.H3O+ i. NaOEt ii.PhCH2Br O O O Ph Ph I O Ph O III II O Ph O O IV A) B) C) D) E) Ans: heat (-CO2) I II III IV V C Ph V P Chapter 19 Topic: Reaction Products 13. Predict the product of the following reaction sequence. i. NaOC2H5 O O O ii. CH3CH2CH2Br ? iii. NaOH iv. H3O+, heat O OH O OH O O O I II III O OH IV A) B) C) D) E) Ans: I II III IV V D O O V O Chapter 19 Topic: Reaction Products 14. What is the product, W, of the following reaction sequence? O (2 eq) O O O .. Na i. NaOH heat (-CO2) + ii.H3O (1 eq) + CO2H HO2C Br Br HO2C CO2Et EtO2C CO2H II I III O CO2H O IV A) B) C) D) E) Ans: V I II III IV V B Topic: Reaction Products 15. Predict the product of the following reaction sequence. i. NaOEt, EtOH O O O ii. NaOH, heat + O O O + iii. H3O iv. heat ? O OH O O O O O I II OH O O OH IV A) B) C) D) E) Ans: I II III IV V B O III OH HO O O V W O Chapter 19 Topic: Reaction Products 16. The product, L, of the following reaction sequence, O i. EtBr ii. (CH3)3COK H2N NH2 EtO2C CO2Et + NaOEt − iii. MeI EtO O O MeO Me EtO2C OEt NH2 HN EtO2C N H O Et O N H Me Et O CO2Et CO2Et NH N H O II I O N H O O H2N N H O Me Et O N H NH2 V IV A) B) C) D) E) Ans: O O N H n O III O N H N H ? I II III IV V C Topic: Reaction Products 17. The product(s) of the reaction of 2 mol of ethyl butanoate with sodium ethoxide is(are): O A) OH + NaOH O O B) O C) O O O D) O O O E) O O O Ans: C Chapter 19 Topic: Reaction Products 18. The reaction of diethyl heptanedioate with sodium ethoxide would give as the product: O O EtO EtO I O II O OEt III A) B) C) D) E) Ans: O O O IV O V I II III IV V C Topic: Reaction Products 19. The product of the following reaction is: O weak O + CN base O O OH CN CN O O O CN O I II III O O OMe IV I II III IV V D NH O OMe CN A) B) C) D) E) Ans: ? V Chapter 19 Topic: Reaction Products 20. Which product can be obtained via the following generalized reaction? O R-I + CN EtO O I O R EtO R EtO N I IV CN R II III O A) B) C) D) E) Ans: ? O CN EtO NaOEt EtOH O R CN RO V I II III IV V A Topic: Reaction Products 21. Malonic ester (diethyl malonate) is treated successively with sodium ethoxide (1 eq.), ethyl bromide, potassium tert-butoxide, isobutyl chloride, hot aqueous NaOH, HCl, and heat. What is the final product? A) 4-Ethyl-2-methylpentanoic acid B) 6-Methylheptanoic acid C) 2-Ethyl-3-methylpentanoic acid D) 2-Ethyl-4-methylpentanoic acid E) Ethylisobutylmalonic acid Ans: D Topic: Reaction Products 22. Malonic ester (diethyl malonate) is treated successively with sodium ethoxide (1 eq.), 1bromopentane, potassium tert-butoxide, iodomethane, hot aqueous NaOH, HCl, and heat. What is the final product? A) 2-Methylheptanoic acid B) 3-Methylhexanoic acid C) 3-Methylpentanoic acid D) 2-Methylpentanoic acid E) Ethyl 2-methylheptanoate Ans: A Chapter 19 Topic: Reaction Products 23. What is the product of the Dieckmann condensation of this diester, O OEt EtO O O O OEt I A) B) C) D) E) Ans: O O O OEt O II OEt III I II III I and II I, II, and III D Topic: Reaction Products 24. What product(s) is (are) likely to be obtained upon Dieckmann condensation of the following substance? O O O O O O O O I A) B) C) D) E) Ans: O O O II I and II II and III III and IV I and III II and IV D O O O O O III IV Chapter 19 Topic: Reaction Products 25. The Thorpe reaction of dinitriles is analogous to the Dieckmann condensation of diesters. What is the product predicted to result from the use of N≡CCH2CH2CH2CH2C≡N and sodium ethoxide? NH NH HN CN NH CN II I NH III CN NC NC CN CN IV A) B) C) D) E) Ans: V I II III IV V A Topic: Reaction Products 26. What product(s) result from the Claisen condensation carried out with an equimolar mixture of ethyl acetate and ethyl propanoate? O O O O I I II III IV All of these E O O O A) B) C) D) E) Ans: O II O O O III O IV Chapter 19 Topic: Reaction Products 27. What product(s) result from the Claisen condensation carried out with an equimolar mixture of ethyl 2-methylpropanoate and ethyl propanoate? O O O O O O O O O O II I A) I and II B) I and IV C) I, II and IV D) II and III E) All of these Ans: E O III O IV Topic: Reaction Products 28. What product is finally formed when the initial compound formed from cyclohexanone and pyrrolidine is mixed with allyl chloride and that product is heated and then hydrolyzed? O HO N II I O IV A) B) C) D) E) Ans: I II III IV V B III O V Cl Chapter 19 Topic: Reaction Products 29. What is the major product of the following reaction? O EtO O O O Q O OEt O OEt O O OEt i. O ii. H3O+ NaNH2 Et2O OEt O I II III O O OEt O OEt O O IV A) B) C) D) E) Ans: V I II III IV V B Topic: Reaction Products 30. What is the structure for R? i. C4H9Li, Et2O ii. C6H5CH2Br H Ph HgCl2 MeOH, H2O S S R Ph O Ph Ph CHO CHO I II III OH Ph Ph CHO IV A) B) C) D) E) Ans: I II III IV V C V O Chapter 19 Topic: Reaction Products 31. What is the final product from the following reaction sequence? i. C4H9Li, Et2O ? S S Ph ii. C2H5Br H iii. HgCl2, CH3OH, H2O S S S S H Ph Ph Ph S II I III Ph O O Ph IV A) B) C) D) E) Ans: SH V I II III IV V D Topic: Synthesis 32. Which of the following might be used to synthesize the following substance? OH Ph A) PhCO2Et OH CH3CH2CO2Et NaOEt, EtOH H3O+ LiAlH4 Et2O H2O Mg LiAlH4 H3O+ PhCHO + CH3CHBrCH2CO2Et Et2O Et2O Mg C) H2O PhCHO CH3CHBrCH2CO2Et Et2O D) Answers A) and B) E) Answers A), B), and C) Ans: A B) H2O Chapter 19 Topic: Synthesis 33. Which of the following might be used to synthesize the following substance? OH Ph OH O A) Ph i. O , NaOEt, EtOH O ii. H3O+ O iii. LAH, Et2O iv. H2O O B) B. Ph O i. , NaOEt, EtOH O + ii. H3O O iii. LAH, Et2O iv. H2O O C) O C. Ph O i. ii. H3O Br + iii. LAH, Et2O iv. H2O D) Answers A) and C) E) Answers B), and C) Ans: B , Mg, Et2O Chapter 19 Topic: Synthesis 34. Which of the following could be used to synthesize the following substance in good yield? CO2H O Cyclohexanone, ClCH2COOH, AlCl3, heat Cyclohexanone, (CH3CH2)2NH, HA, (-H2O); then BrCH2COOC2H5; then OH-, H2O, heat; then H3O+ C) Cyclohexylacetic acid, KMnO4, OH-, heat; then H3O+ D) Answers A) and B) E) Answers A), B), and C) Ans: B A) B) Topic: Synthesis 35. Which of the following could be used to synthesize the following substance in good yield? O OH O Cyclopentanone, ClCH2CH2COOH, AlCl3, heat Cyclopentanone, (CH3CH2)2NH, HA, (-H2O); then BrCH2CH2COOC2H5; then OH-, H2O, heat; then H3O+ C) 3-(2-hydroxycyclopentyl)propanal, KMnO4, OH-, heat; then H3O+ D) Answers A) and B) E) Answers B) and C) Ans: E A) B) Topic: Synthesis 36. Which of the following would provide the best synthesis of 3,5-dimethyl-2-hexanone? A) Ethyl acetoacetate + NaOC2H5 + CH3I; then KO-t-Bu + (CH3)3CCH2Br; then NaOH; then H3O+; then heat B) Ethyl acetoacetate + NaOC2H5 + (CH3)3CBr; then KO-t-Bu + CH3I; then NaOH; then H3O+; then heat C) Ethyl acetoacetate + NaOC2H5 + (CH3)2CHCH2Br; then KO-t-Bu + CH3I; then NaOH; then H3O+; then heat D) Ethyl acetoacetate + NaOC2H5 + (CH3)2CHCH2CHBrCH3; then NaOH; then H3O+; then heat E) Ethyl acetoacetate + NaOC2H5 + CH3I; then KO-t-Bu + (CH3)2CHBr; then NaOH; then H3O+; then heat Ans: C Chapter 19 Topic: Synthesis 37. Which of the following would provide the best synthesis of 3-ethyl-6-methyl-2heptanone? A) Ethyl acetoacetate + NaOC2H5 + CH3CH2I; then KO-t-Bu + (CH3)3CCH2CH2Br; then NaOH; then H3O+; then heat B) Ethyl acetoacetate + NaOC2H5 + (CH3)3CCH2Br; then KO-t-Bu + CH3CH2I; then NaOH; then H3O+; then heat C) Ethyl acetoacetate + NaOC2H5 + (CH3)2CHCH2CH2Br; then KO-t-Bu + CH3CH2I; then NaOH; then H3O+; then heat D) Ethyl acetoacetate + NaOC2H5 + (CH3)2CHCH2CH2CHBrCH2CH3; then NaOH; then H3O+; then heat E) Ethyl acetoacetate + NaOC2H5 + CH3CH2I; then KO-t-Bu + (CH3)2CHCH2Br; then NaOH; then H3O+; then heat Ans: C Topic: Synthesis 38. Which of the following would afford the best synthesis of diethyl phenylmalonate, O O C2H5O OC2H5 Ph A) O Ph Br + C2H5O .. Na B) O NaOC2H5 H3O+ + OC2H5 C2H5O OC2H5 C2H5OH O O NaOC2H5 H3O+ + OC2H5 C H OH OC2H5 C2H5O 2 5 O Ph C) Ph OC2H5 + O O D) O O D. Ph OC2H5 + E) Ph CHO Ans: B + 2 O H NaOC2H5 OC2H5 C2H5OH NaOC2H5 OC2H5 C2H5OH H3O+ H3O+ Chapter 19 Topic: Synthesis 39. What product is formed during the following reaction? O O i. NaOC2H5, C2H5OH + Ph OC2H5 OC2H5 ii. HOAc O O OC2H5 Ph O O Ph Ph OC2H5 O O III II I O Ph OH O O O Ph IV A) B) C) D) E) Ans: OC2H5 V I II III IV V B Topic: Synthesis 40. Which compound may be prepared using a Mannich reaction? CO2Et O CO2H I CO2Et N III II O O O N IV A) B) C) D) E) Ans: O I II III IV V C V Chapter 19 Topic: Synthesis 41. Which compound could be prepared using a Michael reaction? O O O HO OC2H5 O III II I O O O O O OC2H5 IV A) B) C) D) E) Ans: V I II III IV V C Topic: Synthesis 42. Which compound could be prepared via Dieckmann condensation? O O O HO OC2H5 O III II I O O O O O IV A) B) C) D) E) Ans: I II III IV V D O V Chapter 19 Topic: Synthesis 43. Which reagents would you use to prepare the following substance from ethyl acetoacetate? O O Ph A) i) NaH/DMSO; ii) PhCOCl; iii) OH−/H2O, heat; iv) H3O+; v) heat B) i) NaOEt/EtOH; ii) PhCOCH2Br; iii) OH−/H2O, heat; iv) H3O+; v) heat C) i) heat; ii) NaOEt/EtOH; iii) PhCOCH2Br D) i) NaOEt/EtOH; ii) PhCl E) i) NaOEt/EtOH; ii) PhCOCl; iii) OH−/H2O, heat; iv) H3O+; v) heat Ans: A Topic: Synthesis 44. Which of the following statements is true about the anion formed from the reaction of diethyl malonate with sodium ethoxide? A) It can react with an ∝, β-unsaturated ester by conjugate addition. B) It can condense with aldehydes and ketones. C) It can be alkylated with an alkyl halide. D) It is resonance stabilized. E) All of the above statements are true. Ans: E Chapter 19 Topic: Synthesis 45. Which reagents would be used in a Mannich reaction to synthesize O N O I + O H + (CH3)2NH O II O + H + (CH3)3N O III + (CH3)3N + base O IV + H O H + (CH3)2NH O V A) B) C) D) E) Ans: + (CH3)2NH I II III IV V D Chapter 19 Topic: Synthesis 46. What combination of reagents can be used to make the following substance via an enamine? O O O I + NH + O O II + NH + O O III + Cl + O NH O IV A) B) C) D) E) Ans: + O + NH2 I II III IV Both reactions II and III C Topic: Synthesis 47. Which organic reagents would you need to make 2-ethylpentanoic acid from diethyl malonate? A) Bromoethane, 1-bromopropane, sodium ethoxide, and potassium tert-butoxide B) 3-Bromohexane and sodium ethoxide C) 3-Bromopentane and sodium ethoxide D) Bromoethane, 2-bromopropane, sodium ethoxide, and potassium tert-butoxide E) 2-Bromopentane and sodium ethoxide Ans: A Chapter 19 Topic: Synthesis 48. Which organic reagents would you need to make 2-ethylheptanoic acid from diethyl malonate? A) Bromoethane, 1-bromopentane, sodium ethoxide, and potassium tert-butoxide B) 3-Bromooctane and sodium ethoxide C) 3-Bromoheptane and sodium ethoxide D) 1-Bromopropane, 2-bromopentane, sodium ethoxide, and potassium tert-butoxide E) 2-Bromoheptane and potassium tert-butoxide Ans: A Topic: Synthesis 49. 2-Methylcyclohexane-1,3-dione can be synthesized from: O H3O+ CH3MgBr I O O KMnO4, OH− II O O III O O A) B) C) D) E) Ans: I II III IV V C i. NaOEt ii. H3O+ OEt i. NaOEt ii. H3O+ OEt i. NaOEt ii. H3O+ O IV V OEt O Chapter 19 Topic: Synthesis 50. 2-Heptanone can be synthesized by which reaction sequence? − A) NaOEt CH3(CH2)3Br i. dil.OH heat Ethyl acetoacetate + EtOH ii. H O 3 B) C) D) E) CH3(CH2)3Br NaOEt EtOH − i. dil.OH heat NaOEt CH3(CH2)3Br Ethyl acetoacetate + EtOH ii. H3O − i. dil.OH heat Ethyl acetoacetate CH3(CH2)3Br + ii. H3O − i. NaOEt, EtOH i. dil.OH heat Ethyl hexanoate ii. CH3COCl ii. H O+ Ethyl acetoacetate heat 3 Ans: A Topic: Synthesis 51. Consider the synthesis below: What is compound X? CO2Et A) B) C) D) E) Ans: + X i. NaOEt, EtOH ii. H3O+ CO2Et CO2Et O=C(OEt)2 HCO2Et EtO-CO-CO-OEt CH3CO2Et BrCH2CO2Et A Topic: Synthesis 52. Consider the synthesis above. What is compound Y? CO2Et CO2Et 1) KOt-Bu 2) "Y" 1) NaOH/H2O, heat 2) H3O+ 3) heat (− CO2) A) B) C) D) E) Ans: BrCH2CO2Et EtO-CO-CO-OEt CH3CH2Br C6H5CH2Br C6H5Br D CO2Et Chapter 19 Topic: Synthesis 53. Consider the synthesis below. What is compound Z? CO2Et CO2Et 1) KOt-Bu 2) "Y" "Z" CO2Et 1) NaOH/H2O, heat 2) H3O+ 3) heat (− CO2) CO2Et EtO2C I IV I II III IV V B EtO2C II EtO2C CO2Et A) B) C) D) E) Ans: CO2Et CO2Et III O CO2Et V Chapter 19 Topic: Synthesis 54. The Knoevenagel condensation of p-methoxybenzaldehyde with ethyl acetoacetate in the presence of diethylamine produces which of these? CO2Et O OH CO2Et O MeO O MeO I EtO2C MeO II III O O CO2Et CO2Et O MeO IV A) B) C) D) E) Ans: O MeO V I II III IV V A Topic: Synthesis 55. What alkylating agent would be used with 2-phenylethanal in the Corey-Seebach method for the preparation of 4-methyl-1-phenyl-2-pentanone? A) Isopropyl bromide B) Butyl bromide C) sec-Butyl bromide D) Isobutyl bromide E) tert-Butyl bromide Ans: D Topic: Synthesis 56. What alkylating agent would be used with 2-phenylethanal in the Corey-Seebach method for the preparation of 6-methyl-1-phenyl-2-heptanone? A) 1-bromo-4-methylpentane B) 2-bromo-4-methylpentane C) 1-bromo-6-methylheptane D) 1-bromo-5-methylhexane E) None of the above could be used Ans: A Chapter 19 Topic: General Information 57. Which of the following statements is true of the enamine, N: A) B) The enamine can be made from cyclohexanone + pyrrolidine. + N : It has another resonance structure : C) It can be acylated at the ∝-carbon of the original carbonyl compound. D) It can be alkylated. E) All of the above are true. Ans: E Topic: General Information 58. Which of the following statements is true of the following enamine? N: A) B) The enamine can be made from cyclopentanone + pyrrolidine. + C) D) E) Ans: It has another resonance structure: It can be acylated at the ∝-carbon of the original carbonyl compound. It can be alkylated. All of the above are true. E N : Topic: General Information 59. In the synthesis of barbiturates (general structure shown below), the R groups would originate in which step? O HN O A) B) C) D) E) Ans: N H R' R O Alkylation of the unsubstituted barbituric acid Alkylation of the urea Alkylation of the starting diethyl malonate Alkylation of an enamine Alkylation via a Grignard reagent C Chapter 19 Topic: General Information 60. Which of these is not a reversible process? A) Base-promoted ester hydrolysis B) Acid-catalyzed ester hydrolysis C) Aldol addition D) Claisen condensation E) Acetal formation Ans: A Topic: General Information 61. The Claisen condensation of which of these esters demands the use of (C6H5)3CNa as the base (as opposed to sodium ethoxide)? A) CH3CH2CO2C2H5 B) CH3CO2C2H5 C) C6H5CH2CO2C2H5 D) C6H5CH(CH3)CO2C2H5 E) None of these Ans: D Topic: General Information 62. The Claisen condensation of which of these esters demands the use of (C6H5)3CNa as the base (as opposed to sodium ethoxide)? A) CH3CH2CH2CO2C2H5 B) CH3CH2CO2C2H5 C) C6H5CH2CH2CO2C2H5 D) (CH3)2CHCH2CO2C2H5 E) None of these Ans: E Topic: General Information 63. Which of these halides is predicted to alkylate malonic ester (as the anion) in highest yield? A) CH3I B) C6H5Br C) (CH3)3CCH2Cl D) CH3CHClCH3 E) All of these should be equally effective. Ans: A Chapter 19 Topic: General Information 64. The Claisen condensation produces which of these? A) An ∝-keto ester B) A β-keto ester C) A β-hydroxy ester D) A β-hydroxyaldehyde E) A β-diketone Ans: B Topic: General Information 65. Cyclization reactions, such as the Dieckmann condensation, are best carried out using fairly dilute solutions of the compound to be cyclized. Why is this so? A) It then is possible to use less base. B) The reagents generally are expensive. C) A smaller amount of the compound to be cyclized can be used. D) Intermolecular condensation is minimized at low concentration. E) The concentration factor is unimportant. Ans: D Topic: General Information 66. Why is CH3ONa not used in the Claisen condensation of ethyl acetate? A) CH3O- is a weaker base than the CH3CH2O- which is used. B) CH3O-Na+ is more difficult to prepare than CH3CH2O-Na+. C) CH3O- would abstract a proton from the ethyl group of the ester. D) Use of CH3O-Na+ would result in transesterification. E) CH3O-Na+ can be used as well as CH3CH2O-Na+. Ans: D Topic: General Information 67. Which of these combinations is not one which would result in the formation of essentially one Claisen condensation product when one compound is added slowly to the mixture of the other and the base employed? HCO2Et + CH3CH2CO2Et A) HCO2Et + CH3CH2CO2Et B) PhCO2Et + CH3CO2Et C) (CO2Et)2 + PhCH2CO2Et D) (CH3)3CCO2Et + CH3CO2Et E) PhCH2CO2Et + CH3CO2Et Ans: E Chapter 19 Topic: General Information 68. Which structure represents an ester enolate? O O O O O O I II A) I B) II C) III D) IV E) Both B) and C) Ans: E O O III III Topic: General Information 69. Which of these amines is/are used with aldehydes and ketones to form enamines? H N I A) B) C) D) E) Ans: NH II N III N III I II III IV Both I and II E Topic: General Information 70. Which base is employed in the alkylation of ethyl pentanoate with methyl iodide? A) Sodium methoxide B) Sodium ethoxide C) Sodium hydride D) Potassium tert-butoxide E) Lithium diisopropylamide Ans: E Topic: General Information 71. Which base is employed in the alkylation of methyl hexanoate with ethyl iodide? A) Sodium methoxide B) Sodium ethoxide C) Sodium hydride D) Potassium tert-butoxide E) Lithium diisopropylamide Ans: E Chapter 19 SHORT ANSWER QUESTIONS Topic: General Information 72. Compounds having two carbonyl groups separated by an intervening carbon atom are called ____________. Ans: β-dicarbonyl compounds Topic: Active hydrogens 73. The pKa for protons on the carbon between two carbonyls is about 9-11. This greater acidity (as compared to single carbonyl systems) can be accounted for by ______________. Ans: resonance delocalization of the negative charge over two carbonyls rather than just one Topic: Claisen condensation 74. Esters frequently react in the presence of alkoxides by a reaction called the __________ condensation. Ans: Claisen Topic: Dieckmann condensation 75. An intramolecular Claisen condensation is known as a _____________. Ans: Dieckmann condensation Topic: General Information 76. When planning a reaction with an ester and an alkoxide ion, it is important to use an alkoxide that has the same alkyl group as the ester in order to avoid ________________. Ans: transesterification Topic: Synthetic Strategy 77. The ethyl acetoacetate anion is the synthetic equivalent of the ___________. Ans: acetone enolate Topic: Malonic Ester synthesis 78. A reaction of a particular β-dicarbonyl compound that gives substituted or disubstituted acetic acids is called the _____________. Ans: malonic ester synthesis Topic: Active Hydrogen compounds 79. Compounds with two electron-withdrawing groups attached to the same carbon atom are known as ____________ or _____________. Ans: active hydrogen compounds; active methylene compounds Topic: Synthetic Strategy 80. “Umpolung” is a German term meaning __________. Ans: polarity reversal Chapter 19 Topic: Knoevenagel Condensation 81. An aldol-type condensation between an active methylene compound and an aldehyde or ketone is called a _____________. Ans: Knoevenagel condensation Topic: Synthetic Strategy 82. In Chapter 16 we learned an efficient method for the crossed aldol condensation using lithium diisopropylamide as the base. This was specific for forming the kinetic enolate in ketones. If we instead wished to access the thermodynamic enolate instead, what method should we use? Ans: The Stork enamine synthesis; convert the ketone to the enamine, which will form the more highly substituted double bond and act as a synthetic equivalent for the thermodynamic enolate. Topic: General Information 83. Physiologically speaking, barbiturates are very effective __________. Ans: soporifics or sleep-inducers Topic: Claisen Condensation 84. Explain why ethyl 2-methylpropanoate does undergo the usual Claisen condensation. Ans: In order for Claisen condensation to occur efficiently, there must be at least 2 hydrogen atoms alpha to the ester group. Although only one hydrogen appears to be substituted during the reaction, a second alpha hydrogen must originally be present, otherwise the overall reaction has an unfavorable equilibrium. Topic: Dieckmann Condensation 85. Explain why diethyl pentanedioate does undergo a Dieckmann condensation. Ans: Dieckmann condensation of diethyl pentanedioate would afford a four-membered ring. This ring is expected to have a considerable degree of ring strain and can account for the observed lack of reactivity. O O O O O O O Topic: Dieckmann Condensation 86. Predict what is likely to happen when ethyl 6-oxooctanoate is treated with NaOEt, followed by acid work-up. Ans: A cyclization similar to Dieckmann condensation is likely to occur, giving 2propanoylcyclopentanone as the major product: O O O O O Chapter 19 Topic: Acylation of Active Hydrogen Compounds 87. Explain why acylation of active methylene compounds must be carried out in aprotic solvents, typically using NaH to generate the enolate anion: why can sodium ethoxide/ethanol not be used in these reactions? Ans: Acylating agents such as acyl halides and acid anhydrides would react rapidly with ethanol to form esters; also, during this process, the ethoxide ion would be neutralized. NaH/aprotic solvent bypasses these issues and affords the expected products in good yields. Topic: 1,3-Dithiane Reactivity 88. Explain how the reactivity of 1,3-dithianes is different from that of the aldehydes from which they are typically prepared. Ans: The carbonyl carbon of an aldehyde is partially positive and thus, reacts with nucleophiles. By contrast, upon conversion into a dithiane and subsequent treatment with butyllithium, this same carbon becomes negatively charged, and reacts with electrophiles. This phenomenon is described as “umpolung”. Topic: Multistep Reaction Sequence: 89. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. CO2Et i. NaH ? CO2Et ii. Br Br iii. NaOEt iv. NaOH, heat v. H3O+, heat Br Ans: CO2Et NaH CO2Et Br CO2Et Br +− Na : CO2Et CO2Et CO2Et NaOEt CO2H i. NaOH, heat ii. H3O+, heat CO2Et CO2Et Chapter 19 Topic: Multistep Reaction Sequence: 90. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. NH , p-TsOH i. O ? O ii. O , EtOH, reflux iii. H2O Ans: O : NH O N p-TsOH Br N + O EtOH, reflux O O H2O O O O Topic: Multistep Reaction Sequence: 91. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. NH , p-TsOH i. O ? O ii. Br O iii. H2O Ans: NH O : O N Br N + Br O p-TsOH O O H2O O O O Chapter 19 Topic: Multistep Reaction Sequence: 92. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. O O i. Zn, Br O ? ii. NH4Cl iii. PCC iv. t-BuOK, t-BuOH v. CH3I O Ans: i. Zn, O OH O Br O O ii. NH4Cl PCC O O O i. t-BuOK, t-BuOH ii. CH3I O O O Topic: Multistep Reaction Sequence: 93. What is the expected final product when phenylacetonitrile is subjected to the following reaction sequence? i. EtO-, EtOH CN ? ii. CH3CH2I Ans: i. EtO-, EtOH CN CN ii. CH3CH2I Chapter 19 Topic: Multistep Reaction Sequence: 94. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. O O i. Cl2, FeCl3 ii. ? - O , EtO , EtOH O Ans: O O O Cl2, FeCl3 O O O O O O - EtO , EtOH Cl Cl Topic: Synthetic Strategy 95. Suggest a reasonable synthetic strategy to carry out the following transformation. OH O O O2N O2N OH Ans: O O2N O NO2 O O EtO-, EtOH O2N O NO2 i. LAH ii. H2O OH O2N OH NO2 Chapter 19 Topic: Synthetic Strategy 96. Suggest a reasonable synthetic strategy to carry out the following transformation. O O Br O Br Br O O Ans: O EtO-, EtOH O Br O Br Br H3O+, heat O O Br Br OH O Br Br Topic: Multistep Reaction Sequence 97. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. O O i. EtO-, EtOH O ii. H3O+ O ? iii. NaBH4, H2O Ans: O O O O i. EtO-, EtOH ii. H3O+ NaBH4 H2O O O O HO O O Chapter 19 Topic: Multistep Reaction Sequence 98. What is the final product of the following reaction sequence? Give structural details of all significant intermediates. i. NaH, DMF O O ? ii. CH3CH2COCl O iii. NaOH, H2O iv. H3O+, heat Ans: O O O i. NaH, DMF O ii. CH3CH2COCl O i. NaOH, H2O OO ii. H3O+, heat O O O OH O O Topic: Reaction Products 99. Suggest a reasonable synthetic strategy for the synthesis of 3-heptanone from propanal. SH S Ans: O HS + H3O S propanal i. n-BuLi ii. I O 3-heptanone HgCl2 CH3OH, H2O S S Chapter 19 Topic: Reaction Products 100. Suggest a reasonable mechanism for the following reaction. O + O O O i.EtONa, EtOH, 25oC ii. H3O+ O O O O O .. − EtO : + .. O O EtOH + H O −: O O O : O O : Ans: O O O O O − .. O O O :O : O O O O O O H3O+ O O O :O : O :O .. : − O O Chapter 20 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. Which of these is an acceptable alternative name to "(1-methylbutyl)amine"? A) 2-Aminopentane B) 2-Pentanamine C) Isopentylamine D) sec-Pentylamine E) Both A) and B) Ans: E Topic: Nomenclature 2. Which is a correct common name for the following substance? N A) B) C) D) E) Ans: Ethylethylisobutylamine Diethylisobutylamine sec-Butyldiethylamine Ethylethyl-sec-butylamine 2-Diethylaminobutane C Topic: Nomenclature 3. Which of the following is a tertiary amine? A) CH3CH2CH2CH2NH2 B) CH3CH2NHCH2CH(CH3)2 C) (CH3CH2)2NCH2CH(CH3)2 D) (CH3CH2)4N+ OHE) (CH3CH2)3CNH2 Ans: C Topic: Nomenclature 4. What type of amine is N-methyl-2-methyl-3-hexanamine? A) Primary B) Secondary C) Tertiary D) Quaternary E) None of these Ans: B 747 Chapter 20 Topic: Nomenclature 5. Which of these is properly termed a "quaternary ammonium salt"? A) (CH3)3CCH2CH2NH3+ Cl− B) (CH3CH2CH(CH3)CH2)2NH2+ Cl− C) (CH3CH2CH2)3NH+ Cl− D) (CH3CH2CH2)4N+ Cl− E) None of these Ans: D Topic: Chemical Tests and Separations 6. Which reagent would serve as the basis for a simple chemical test that would distinguish between the pair of compounds listed below? H N NH2 and A) B) C) D) E) Ans: AgNO3 in H2O Dilute NaHCO3 Dilute NaOH C6H5SO2Cl/OH-, then H3O+ Dilute HCl D Topic: Chemical Tests and Separations 7. Which reagent would serve as the basis for a simple chemical test that would distinguish between the pair of compounds listed below? NH2 and A) B) C) D) E) Ans: NH2 AgNO3 in H2O HONO, 0-5°C then β-naphthol Dilute NaOH C6H5SO2Cl and OH- in H2O Dilute HCl B Topic: Chemical Tests and Separations 8. Which reagent will distinguish between C6H5NH2 and (C6H5)2NH? A) HCl (aq) B) NaOH C) C6H5SO2Cl/OH-, then H3O+ D) Br2/CCl4 E) KMnO4 Ans: C 748 Chapter 20 Topic: Chemical Tests and Separations, Nomenclature 9. Which reagent will distinguish between 2-amino-2,3-dimethylpentane and 1-amino-3methyl-2-pentene? A) HONO, 0-5°C B) C6H5SO2Cl/OH-, then H3O+ C) NaOH D) HCl E) Br2/CCl4 Ans: E Topic: Chemical Tests and Separations, Nomenclature 10. Which reagent could be used to separate a mixture of aniline and toluene? A) KMnO4 in H2O B) Dilute NaOH C) Dilute NaHCO3 D) Ag(NH3)2OH E) Dilute HCl Ans: E 749 Chapter 20 Topic: Chemical Tests and Separations 11. Compound W has the molecular formula C11H17N. Treatment of W with benzenesulfonyl chloride in base gives no reaction. Acidification of the resulting mixture gives a clear solution. The 1H NMR spectrum of W consists of: δ 1.0 δ 2.5 δ 3.6 (2H) δ 7.3 (5H) triplet, quartet, singlet, multiplet, The most likely structure for W is: A) N H B) N C) N D) N E) N Ans: B Topic: Chemical Tests and Separations 12. Which of these could be resolved into separate enantiomers? A) 4-methyl-1-pentanamine B) 4-methyl-2-pentanamine C) N-methyl-1-butanamine D) N,N-dimethyl-1-propanamine E) N-Butyltrimethylammonium bromide Ans: B 750 Chapter 20 Topic: Reaction Products 13. What final product is expected from the following reaction sequence? i. Fe/HCl NO2 ii. NaHCO3 ? iii. Br2/H2O Cl iv. HONO, 0-5oC v. H3PO2 Br Br Br OH NO2 Cl Br Cl I III II Br Br PO2H Br Cl IV A) B) C) D) E) Ans: Cl NO HO2P Cl V I II III IV V B 751 Chapter 20 Topic: Reaction Products 14. What compound is likely to be obtained via the following reaction sequence? i. HONO, 0-5oC NH 2 Br Br ii. CuCl ? iii. Fe/HCl NO2 iv. NaOH, H2O o v. HONO, 0-5 C vi. H3PO2 Br Br Br Br Br Br A) B) C) D) E) Ans: Cl NO2 I II Cl Cl Br Br Br Br PO2H III I II III IV V C 752 IV V Chapter 20 Topic: Reaction Products 15. What would be the product, L, of the following reaction? Cl NH2 i. NaCN ii. H2, Ni ? CN N H I III II NH2 IV A) B) C) D) E) Ans: V I II III IV V E Topic: Reaction Products 16. What final product is expected when toluene is subjected to the following reaction sequence? i) KMnO4, NaOH; ii) H3O+ ( product = C7H6O2); iii) SOCl2; iv) NH3 (product = C7H7NO); v) Br2, NaOH A) C6H5CONH2 B) C6H5CH2NH2 C) p-CH3C6H4SO2NH2 D) p-CH3C6H4NH2 E) C6H5NH2 Ans: E 753 Chapter 20 Topic: Reaction Products 17. What would be the product of the following reaction sequence? Cl i) , AlCl3 O ? ii) (CH3)2NH iii) LiBH3CN N O O N N II I III OH N N IV A) B) C) D) E) Ans: V I II III IV V C 754 Chapter 20 Topic: Reaction Products 18. What would be the product of the following reaction sequence? i. CH3I ? N ii. Ag2O, H2O iii. heat OH N I A) B) C) D) E) Ans: N N N II III IV I II III IV Answers A) and C) only A Topic: Reaction Products 19. Which product could not be formed during the following reaction? NH2 HONO 0-5oC ? OH OH I II III HO IV A) B) C) D) E) Ans: OH V I II III IV V E 755 Chapter 20 Topic: Reaction Products 20. What would be the product of the following reaction sequence? i. Fe/HCl iv. NaOH, H2O NO2 ? iii. Br2/H2O v. HONO, 0-5oC vi. H3PO2 Cl Br Br OH II I A) B) C) D) E) Ans: Br Br PO2H Br NO2 III Br Br PO2H NO IV V I II III IV V B Topic: Reaction Products 21. Identify the compound (Z) formed when aniline is subjected to the following series of reactions: i.) NaNO2, H2SO4, dil.H2SO4 0-5oC; ii) Cu2O, Cu(NO3)2 , H2O A) B) C) D) E) Ans: C6H5NH2 C6H5Cl C6H5OH C6H6 None of these C Topic: Reaction Products 22. Which is the predominant product formed when m-dinitrobenzene is treated with H2S/NH3 ? A) m -HSC6H4NH2 B) m -C6H4(NH2)2 C) m -HOC6H4NH2 D) m -H2NC6H4NO2 E) C6H5NH2 Ans: D 756 Chapter 20 Topic: Reaction Products 23. Which is the major product of the following reaction? NH2 i. HONO, 0-5oC ii. ? , NaOH OH NO2 OH OH I III II HO N N N OH N V IV 2 A) B) C) D) E) Ans: I II III IV V E Topic: Reaction Products 24. What is the final product? OH i. Fe/HCl − ii. OH C7H9N i. Br2(excess) ii. H2O product i. HONO, 0-5oC ii. H2O, Cu2O, Cu(NO3)2 Final Product A) B) C) D) E) Ans: 2-Bromo-4-methylaniline 2,6-Dibromo-4-methylaniline 2,6-Dibromo-4-methylphenol 2,4-Dibromophenol 3,5-Dibromotoluene C 757 Chapter 20 Topic: Reaction Products 25. What is the final product, C? O NH3 excess O + NH4 + C4H5NO3 − H3O+ Br2 C4H7NO3 OH− C O HO O NH2 O CO2− H2N I A) B) C) D) E) Ans: − − O2C II NH2 O Br O2C O NH2 III IV I II III IV V C Topic: Reaction Products 26. What would be the product of the following reaction sequence? i) KMnO4, NaOH, heat Br ii) H3O+ ? iii) PCl5 iv) NaN3 v) heat vi) H2O A) B) C) D) E) Ans: p-bromobenzamide p-bromobenzaldehyde oxime p-bromobenzenesulfonamide p-bromoaniline 4-bromo-3-chlorobenzoic acid D 758 N-Br O V Chapter 20 Topic: Reaction Products 27. What is the final product of the following sequence of reactions? H2S, NH3 EtOH O2N i. HONO, 5oC C6H6N2O2 ii. KI Final product NO2 A) B) C) D) E) Ans: 1-Iodo-3-nitrobenzene 3-Nitroaniline 3-Nitrophenol 3-Nitrosoaniline 3-Nitrosophenol A Topic: Reaction Products 28. When an equimolar mixture of ammonia and butyl bromide reacts, which of these products will form? A) Butylamine B) Dibutylamine C) Tributylamine D) Tetrabutylammonium bromide E) All of these Ans: E Topic: Reaction Products 29. What is the chief alkene product when butylethylmethylpropylammonium hydroxide is heated to 150°C? A) CH2=CH2 B) CH3CH=CH2 C) CH3CH2CH=CH2 D) E-CH3CH=CHCH3 E) Z-CH3CH=CHCH3 Ans: A 759 Chapter 20 Topic: Synthesis 30. Which of the following reactions would yield C6H5CH2NH2? A) i. NaCN Br ii. LiAlH4, ether iii. H2O NH3 B) O H2, Ni C) i. NaN3 Br ii. LiAlH4, ether iii. H2O D) All of these E) Answers B) and C) only Ans: E Topic: Synthesis 31. Which of the following reaction sequences would yield aniline? A) i. HNO3, H2SO4 ii. Fe, HCl iii. NaOH, H2O Cl B) i. NH3 O C) Br − ii. Br2,OH i. NH3 (excess) ii. HONO, 0-5oC, ether iii. H3PO2 D) All of the above E) Answers A) and B) only Ans: E 760 Chapter 20 Topic: Synthesis 32. Which of the following might be used to synthesize m-bromoaniline? A) i. HNO3, H2SO4 ii. Fe, HCl iii. NaOH, H2O iv. Br2, H2O Cl B) i. Br2, FeBr3 O ii. HNO3, H2SO4 iii. H2, Pt OH C) i. Br2, FeBr3 O ii. SOCl2 iii. NH3 iv. Br2, NaOH D) Answers A) and B) E) Answers B) and C) Ans: C Topic: Synthesis 33. The best synthesis of 3,5-dibromotoluene would be: A) Toluene, Br2, Fe and heat B) p-CH3C6H4NH2, Br2, H2O; then HONO, 0-5°C; then H3PO2 C) Toluene, fuming HNO3, H2SO4; then NH3, H2S; then HONO, 0-5°C; then CuBr D) m-Dibromobenzene, CH3Cl, AlCl3, heat E) m-Bromotoluene, HNO3, H2SO4; then NH3, H2S; then HONO, 0-5°C; then CuBr Ans: B Topic: Synthesis 34. The best synthesis of m-dibromobenzene would be: A) Benzene, Br2, FeBr3, heat B) Aniline, Br2, H2O; then HONO, 0-5°C; then CuBr C) Nitrobenzene, HNO3, H2SO4, heat; then Fe/HCl (excess); then 2 HONO, 0-5°C; then 2 CuBr D) Bromobenzene, HNO3, H2SO4; then Fe, HCl, C2H5OH, reflux; then HONO, 05°C; then CuBr E) Answers C) and D) Ans: C 761 Chapter 20 Topic: Synthesis 35. The best synthesis of m-fluoronitrobenzene would be: A) Nitrobenzene, fuming HNO3, H2SO4, heat; then NH3, H2S; then HONO, 0-5°C; then HBF4; then heat B) Aniline, F2, heat C) Fluorobenzene, HNO3, H2SO4, heat D) o-Nitroacetanilide, NH3, H2S; then Br2, OH-; then HF E) m-C6H4(NH2)2, HONO, 0-5°C; then CuNO2; then HBF4 Ans: A Topic: Synthesis 36. Which is the best preparation of benzonitrile, C6H5CN, from benzene? A) HNO3; then Fe/HCl; then HONO, 0-5°C; then CuCN B) CH3I, AlCl3; then hot KMnO4; then H3O+; then SOCl2; then NH3; then NaOH + Cl2 C) CH3I, AlCl3; then Br2, hν; then KCN D) Br2, Fe; then KCN E) CH3I, AlCl3; then Br2 (2 eq.), hν; then hot NaOH; then HCN Ans: A Topic: Synthesis 37. Which of the following can be used to prepare 2-aminopentane (pure)? I. (1mol) 2-bromopentane + (1mol) NH3 II. (1mol) 2-bromopentane + (1mol) NaN3 III. Phthalimide A) B) C) D) E) Ans: KOH 2-bromopentane I II III I and II II and III E 762 LAH Et2O NH2NH2 C2H5OH Chapter 20 Topic: Synthesis NH2 38. Which is the best method to prepare O A) NH3(excess) H2, Ni Br B) NH3 C) D) CH3NH2 H2, Ni O NO2 NH2 + E) ? + HNO3 HONO 0-5oC hν H2, Ni Ans: A Topic: Synthesis H N 39. Identify the best method(s) to prepare NH2 CH3I A) (1 mol) (1 mol) (CH3)2NH B) O H2, Ni C) O . CH3NH2 H2, Ni D) A) and B) E) B) and C) Ans: C Topic: Synthesis, Nomenclature 40. Your task is to convert o-xylene into o-diaminobenzene. Which sequence of reagents constitutes the best method? A) NaNH2 and heat B) NBS/CCl4; then NH3; then Br2/OHC) KMnO4, OH-, heat; then H3O+; then PCl5; then NH3, then Br2/OHD) KMnO4, OH-, heat; then H3O+; then SOCl2; then NH3; then LiAlH4; then Br2/OHE) KMnO4, OH-, heat; then H3O+; then NH3 with H2/Ni Ans: C 763 Chapter 20 Topic: Synthesis 41. How would one carry out the following transformation: ? ? H2N A) B) C) D) E) Ans: Cl Cl NaNO2,HCl, 0-5°C; then HNO3 NaNO2,HCl, 0-5°C; then H3PO2 NaNO2,HCl, 0-5°C; then H2,Ni C6H5SO2Cl, OH-; then HCl NaH, DMSO B Topic: Synthesis 42. How could one carry out this synthesis? O OH NH2 ? Br A) B) C) D) E) Ans: Br SOCl2; then NH3; then H3PO2 CH3Li, ether; then NH3, H2, Ni SOCl2; then NH3; then Br2, NaOH PCl5; then NH3; then HCl, NaNO2, 0-5°C PCl5; then CH3NH2; then KMnO4, OH-, heat C Topic: Synthesis 43. Consider the synthesis below. What is reagent A? NO2 NH2 A A) B) C) D) E) Ans: B C Br Br Br2, FeBr3 Fe, HCl; then OH− NH2Cl, AlCl3 H3PO2 LiNH2 B 764 Chapter 20 Topic: Synthesis 44. Consider the synthesis below. What is compound B? NO2 NH2 A B C Br Br NO2 NH2 Br Br Br II I III NO2 NH2 Br Br Br IV A) B) C) D) E) Ans: V I II III IV V C Topic: Synthesis 45. Consider the synthesis below. What is reagent C? NO2 NH2 A A) B) C) D) E) Ans: B C Br Br excess Br2, H2O Fe, HCl; then OHNH2Cl, AlCl3 CuBr HNO3, H2SO4, Fe A 765 Chapter 20 Topic: Synthesis 46. Consider the synthesis below. What is reagent A? NH2 Br A) B) C) D) E) Ans: CN Br i. HCl, NaNO2 ii. "A" Br Br H3PO2 HCN P4O10 CuCN CuCl2 D Topic: Synthesis 47. What reagent can effect the following transformation? CN Br A) B) C) D) E) Ans: Br Br ? CO2H Br CO2; then H3O+ H3O+, heat Mg; then CO2; then H3O+ LiAlH4, ether KMnO4, OH-, heat; then H3O+ B Topic: Synthesis 48. What reagent can effect the following transformation? Br CO2H Br Br ? CO2H Br CO2H A) B) C) D) E) Ans: + CO2; then H3O H3O+, heat Mg; then CO2; then H3O+ H2O2, heat KMnO4, OH-, heat; then H3O+ E 766 Chapter 20 Topic: Synthesis 49. What reagent can effect the following transformation? NO2 NO2 ? NO2 A) B) C) D) E) Ans: NH2 - Fe/HCl; then OH H2S, NH3, C2H5OH H2, Ni, high pressure Zn(Hg)/HCl Raney Ni B Topic: Synthesis 50. Consider the synthesis below. What is reagent “Z”? NO2 NO2 o i. HONO, 0-5 C ii. "Z" NH2 A) B) C) D) E) Ans: Cl CuCl CuCl2 NaCl KCl HCl/heat A Topic: Synthesis 51. What reagent can effect the following transformation? NO2 NH2 ? Cl A) B) C) D) E) Ans: Fe/HCl; then OHNH2Cl H3PO2 CuCN HONO, then NH3 A Cl 767 Chapter 20 Topic: Synthesis 52. Consider the following reaction: what is the expected product? NH2 Br2, H2O ? Cl Cl NH2 Br Br H2N Cl Br Br NH2 Cl I Br Br II III NH2 NH2 Br Br Br A) B) C) D) E) Ans: Cl Cl IV V I II III IV V B Topic: Synthesis 53. Consider the synthesis below. What is reagent “Y”? NH2 Br Br i. HONO, 0-5oC ii. "Y" Cl A) B) C) D) E) Ans: Br Br Cl Br2/FeBr3 CuBr CuBr2 H3PO2 H3PO4 D 768 Chapter 20 Topic: Synthesis 54. What is the chief product of the Hofmann elimination reaction applied to the compound shown? N OH II I IV A) B) C) D) E) Ans: III V I II III IV V A 769 Chapter 20 Topic: Synthesis 55. What is the principal product when aniline is treated with sodium nitrite and hydrochloric acid at 0-5°C and this mixture is added to p-ethylphenol? OH OH OH N N N I II N III OH HO N N IV A) B) C) D) E) Ans: V I II III IV V A Topic: Synthesis 56. What is the final product in the Curtius rearrangement of the acyl azide formed from butanoyl chloride? NH2 NH2 N II I III O O N H IV A) B) C) D) E) Ans N3 V I II III IV V A 770 C O Chapter 20 Topic: Synthesis 57. Which combination of reactants will not produce O A) i. LiAlH4, ether N ii. H2O H O B) H i. LiAlH4, ether N ii. H2O C) NaBH3CN + H2N H N ? O D) O E) H N + H2N NaBH3CN Br2, NaOH O Ans: E Topic: Synthesis 58. The overall conversion RBr ⎯⎯⎯⎯→ RCH2NH2 can be accomplished by successive application of which of these sets of reagents? A) Mg, ether; then NH3 B) NaN3; then LiAlH4, ether C) NaCN; then LiAlH4, ether D) H2C=O; then NH3 E) H2NOH; then LiAlH4, ether Ans: C Topic: Synthesis 59. Which would be a good method to synthesize m-nitroaniline? A) 1,3-Dinitrobenzene + H2S and NH3 in EtOH B) Aniline + HNO3/H2SO4 C) Aniline + CH3COCl; then HNO3/H2SO4 D) Nitrobenzene + NH3 and AlCl3 E) More than one of the above Ans: A 771 Chapter 20 Topic: Basicity 60. Which of the following compounds would be the strongest base? O NH2 NH2 NH2 I III II NH2 NH2 O2 N IV A) B) C) D) E) Ans: V I II III IV V B Topic: Basicity 61. Which of the following compounds would be the strongest base? N N H NH2 I III II O A) B) C) D) E) Ans: OH N N IV V I II III IV V D Topic: Basicity 62. Which would be the weakest base? A) p-Methylaniline B) p-Methoxyaniline C) Hexylamine D) p-Nitroaniline E) Dipropylamine Ans: D 772 Chapter 20 Topic: Basicity 63. Arrange the following amines in order of decreasing basicity in aqueous solution: NH3 I A) B) C) D) E) Ans: CH3CH2CH2NH2 II (CH3CH2CH2)2NH III (CH3CH2CH2)3N IV IV > III > II > I III > II > IV > I I > IV > II > III II > III > I > IV III > I > II > IV B Topic: Basicity 64. In aqueous solution, which of the following (as the conjugate acid) possesses the smallest value for pKa? A) C6H5NH2 B) NH3 C) (CH3CH2)3N D) (CH3CH2)2NH E) CH3CH2CH2NH2 Ans: A Topic: Basicity 65. Which of these is the strongest acid? NH3 NH3 NH3 O2N II I III NH3 NH3 I IV A) B) C) D) E) Ans: V I II III IV V B 773 Chapter 20 Topic: Basicity 66. Which of these is the strongest acid? O O O II I O A) B) C) D) E) Ans: N N H NH2 III O N H NH3 IV V I II III IV V D Topic: Basicity 67. Which of these compounds is soluble in dilute sodium hydroxide solution? O O NH I O S O H N N III II O N H IV A) B) C) D) E) Ans: N H V I II III IV V A 774 Chapter 20 Topic: Reactive Intermediates and General Considerations 68. Which is not an intermediate in the Hofmann degradation reaction? KOH RCONH2 RNH2 Br2 A) RN=C=O O B) R NHBr O C) .. .. R NBr O D) HO N H R O E) R N Br Br Ans: E Topic: Reactive Intermediates and General Considerations 69. Which of these compounds is expected to possess the lowest boiling point? A) CH3CH2CH2CH2CH2NH2 B) CH3CH2CH2NHCH2CH3 C) (CH3CH2)2NCH3 D) (CH3CH2)2CHOH E) (CH3)3CCH2NH3+ ClAns: C Topic: Reactive Intermediates and General Considerations 70. This type of compound is the only one of these which can be converted by reduction into a 1°, 2° or 3° amine, according to its particular structure: A) Nitrile B) Oxime C) Azide D) Amide E) Nitroalkane Ans: D 775 Chapter 20 Topic: Reactive Intermediates and General Considerations 71. When the aromatic -NH2 group is to be converted to an -OH group via a diazonium salt, the nitrous acid used is generated in situ by the reaction of a nitrite salt with which acid? A) HCl B) HBr C) HNO3 D) H2SO4 E) CH3CO2H Ans: D Topic: Reactive Intermediates and General Considerations 72. The reaction of which of these compounds with nitrous acid results in a stable N-nitroso compound? A) C6H5NH2 B) C6H5N(CH3)2 C) CH3CH2CH2CH2CH2NH2 D) C6H5NHCH3 E) CH3CH2CONH2 Ans: D Topic: Reactive Intermediates and General Considerations 73. When the process ArNH2 ⎯⎯⎯⎯→ ArY is carried out via an intermediate diazonium salt, this salt is isolated only in the case in which Y is which of these groups? A) -F B) -Cl C) -Br D) -I E) -CN Ans: A Topic: Reactive Intermediates and General Considerations 74. What is the basis for the successful resolution of racemic C6H5CHOHCO2H through use of the chiral amine, C6H5CH(NH2)CH3? A) One enantiomer is more soluble than the other. B) The racemic mixture is converted into a single isomer in the basic solvent. C) The diastereomeric salts formed have different solubilities. D) The diastereomeric salts have different boiling points. E) The diastereomeric salts have different melting points. Ans: C 776 Chapter 20 Topic: Reactive Intermediates and General Considerations 75. Which of these alkyl halides cannot be used effectively in a Gabriel amine synthesis? A) 1-bromopentane B) 1-bromo-3-methylbutane C) 2-bromo-3-methylpentane D) 1-bromo-2,3-dimethylbutane E) 2-bromo-2,3-dimethylbutane Ans: E SHORT ANSWER QUESTIONS Topic: Stereochemistry 76. If the three alkyl groups of a tertiary amine are all different, the amine will be chiral. In practice, however, it is virtually impossible to separate the two enantiomers, because they interconvert rapidly through a process called _________________. Ans: nitrogen inversion Topic: Relative Basicity 77. In solution, two factors affect the relative basicity of amines. These factors are: __________________. Ans: electron donation by alkyl substituents and stabilization of the alkylaminium ion by hydrogen bonding with solvent Topic: Relative Basicity 78. Arylamines are less basic than alkylamines because of _______________. Ans: delocalization of the lone pair on nitrogen into the aromatic system Topic: Enantiomer Resolution 79. Explain how an enantiomerically pure amine can be used to resolve racemic forms of acidic compounds. Ans: The amine reacts with the acidic compound to form a pair of diastereomeric salts, which can be easily separated. Topic: General 80. ______________ is used in automotive airbags. Ans: Sodium azide Topic: General, Synthesis of Amines 81. There are two very versatile synthetic methods that can be used to synthesize primary, secondary, and tertiary amines. These methods are: __________________. Ans: reductive amination of aldehydes and ketones, and reduction of amides 777 Chapter 20 Topic: Chemical Analysis 82. While primary amines react with nitrous acid to generate diazonium salts, secondary amines react with nitrous acid to produce _____________. Ans: N-nitrosoamines Topic: UV-Vis Absorption 83. Azo compounds are usually intensely colored because _________________. Ans: the N=N linkage brings two aromatic rings into conjugation, giving an extended π system that generally absorbs in the visible region Topic: General 84. Chemicals that inhibit the growth of microbes are called ______________. Ans: antimetabolites Topic: Hofmann Elimination 85. Eliminations that follow the Hofmann Rule tend to give the ______________ alkene as the major product. Ans: least-substituted Topic: Nomenclature 86. Draw the structure corresponding to the following name: (4Z,3S)-2,4,7-trimethyl-3-amino-4-octene Ans: H2N H Topic: Nomenclature 87. Draw the structure corresponding to the following name: (3S,6R)-6-(2,4-dinitrophenyl)-3-amino-1-heptyne Ans: H2N H CH 3 H NO2 NO2 778 Chapter 20 Topic: Exhaustive Methylation, Hofmann Degradation, Nomenclature 88. Before modern spectroscopic methods were developed, structures of many complex amines were elucidated by examining the products obtained during Hofmann elimination of their quaternary ammonium hydroxides. The typical procedure involved the following steps, repeated as necessary, depending on whether the amine was primary, secondary or tertiary, until the final product was nitrogen-free: i) CH3I (excess); ii) Ag2O, H2O; iii) heat. What product(s) is (are) likely to be formed if 3,4dimethylpiperidine is subjected to the above procedure? Ans: The reaction sequence would need to be repeated twice to obtain a nitrogen-free product, since the starting compound is a secondary amine. The final product expected is 2,3-dimethyl-1,4-pentadiene along with trimethylamine. N H CH3I (excess) N I Ag2O H2O heat N OH N i. CH3I (excess) ii. Ag2O, H2O iii. heat N + Topic: Multistep Reaction Sequence 89. What final product is likely when cyclohexene is subjected to the following reaction sequence? Give structural details of all significant intermediates. i.) H3O+, H2O; ii) PCC; iii) (CH3)2NH; iv) NaBH3CN Ans: OH O N + H3O N (CH3)2NH PCC H2O 779 OH NaBH3CN Chapter 20 Topic: Multistep Reaction Sequence 90. What final product is likely when p-dinitrobenzene is subjected to the following reaction sequence? Give structural details of all significant intermediates. i.) H2S, NH3, EtOH; ii.)CH3CH2COCl; iii.) LiAlH4; iv) H2O Ans: NO2 NH2 H2S, NH3 EtOH HN O CH3CH2COCl NO2 NO2 NO2 i. LiAlH4, Et2O ii. H2O HN NO2 Topic: Multistep Reaction Sequence, Nomenclature 91. What final product is likely when acetophenone is subjected to the following reaction sequence? Give structural details of all significant intermediates. i) Br2, FeBr3; ii) CH3CH2CH2NH2 ; ii.) NaBH3CN Ans: O O Br2 FeBr3 N CH3CH2CH2NH2 Br Br NaBH3CN NH Br 780 Chapter 20 Topic: Gabriel Synthesis 92. Outline the steps involved in the Gabriel synthesis of 3-amino-2-methylpentane. Ans: O NH O KOH O Br NK O N O O NH2NH2 EtOH reflux O NH NH + NH2 O 3-amino-2-methylpentane Topic: Synthesis, Hofmann Rearrangement 93. Outline the steps involved in the synthesis of 4-bromo-3-nitro-aniline from 4bromobenzaldehyde Ans: i. HNO3, H2SO4 ; ii) KMnO4, OH-, H2O; iii) H3O+; iv) SOCl2; v) NH3 vi) Br2, OHO O O − i. KMnO4, OH , H2O HNO3 H2SO4 Br OH NO2 Br + NO2 ii. H3O Br 4-bromobenzaldehyde SOCl2 O NH2 NH2 O Cl NH3 Br2, NaOH NO2 NO2 Br Br 4-bromo-3-nitro-aniline 781 NO2 Br Chapter 20 Topic: Synthetic Strategy 94. Outline the steps involved in the synthesis of 4-bromo-3-nitro-phenol from 4bromobenzoic acid Ans: i) HNO3,H2SO4 ; ii) SOCl2; iii) NH3; iv) Br2, OH-; iv) NaNO2, H3O+, 0-5oC v) Cu2O, Cu(NO3)2, H2O O OH O OH O Cl O NH3 SOCl2 HNO3 H2SO4 NO2 Br NO2 Br NO2 Br Br Br2 NaOH 4-bromobenzoic acid OH N2+ NO2 NH2 Cu2O, Cu(NO3)2 H2O NaNO2, H3O+ 0-5oC NO2 Br NH2 NO2 Br Br 4-bromo-3-nitro-phenol Topic: Synthesis, Nomenclature 95. Outline the steps involved in the synthesis of 3-chloro-4-fluorophenyl acetate from 4aminoacetophenone Ans: i) Cl2, FeCl3; ii) NaNO2, H3O+, 0-5oC; iii) HBF4; iv) heat ; v) MCPBA O O O NaNO2, H3O Cl2 FeCl3 NH2 + o 0-5 C Cl Cl NH2 N2+ 4-aminoacetophenone i. HBF4 ii. heat O O O MCPBA Cl F 3-chloro-4-fluorophenyl acetate 782 Cl F Chapter 20 Topic: Synthesis, Nomenclature 96. What is the principal product when p-toluidine is treated with sodium nitrite and hydrochloric acid at 0-5°C and this mixture is added to o-ethylphenol? NaNO2, HCl Ans: NH2 N2+ 0-5oC p-toluidine OH OH N N Topic: Relative Base Strength 97. Explain why cyclohexylamine is a stronger base than aniline Ans: There are two major reasons for the observed difference in basicity between the two substances: In aniline, the electron pair on N is delocalized over the aromatic ring i) through resonance: this has the effect of decreasing the electron density at the nitrogen atom, relative to cyclohexylamine, in which no such resonance delocalization can occur, leading to lower base strength for aniline. In cyclohexylamine, the N atom is attached to an sp3 carbon, while in ii) aniline the N atom is attached to an sp2 carbon: an sp2 carbon typically exerts a stronger electron-withdrawing effect, effectively decreasing the electron density on the nitrogen atom, resulting in weaker base strength. Topic: Product Analysis by NMR 98. You have just completed an experiment involving the reduction of m-nitrobenzoic acid with Fe/HCl. In order to determine if your reaction has worked as planned, you have obtained the 1H NMR of your crude product. What will you scrutinize the spectrum for, in order to help you make this assessment? Ans: The appearance of 2 new N-H signals, in the range of about 2-6 ppm will be indicative of successful reduction of the –NO2 group to the –NH2 group. These signals are characteristically somewhat broad, and should disappear (or decrease markedly) if the spectrum is rerun with an added drop of D2O to the original sample prepared for obtaining the 1H NMR. The rest of the signals are likely to remain more or less similar, with some changes in chemical shift likely (probably upfield shifts), since the –NO2 group is electron-withdrawing, while the –NH2 group is electron-donating. 783 Chapter 21 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature 1. The common name for 4-methylphenol is which of these? A) Catechol B) p-Cresol C) Resorcinol D) Hydroquinone E) p-Xylenol Ans: B Topic: Nomenclature 2. The common name for 3-methylphenol is which of these? A) Catechol B) m -Cresol C) m-tolylol D) Hydroquinone E) p-Xylenol Ans: B Topic: Nomenclature 3. The common name for 1,2-benzenediol is which of these? A) Catechol B) m -Cresol C) Resorcinol D) Hydroquinone E) o-Xylenol Ans: C Topic: Nomenclature 4. What is the systematic (IUPAC) name for OH OH A) B) C) D) E) Ans: m-Hydroxyphenol m-Dihydroxybenzene Resorcinol 1,3-dihydroxybenzene 1,3-Benzenediol E 784 Chapter 21 Topic: Nomenclature 5. What is the systematic (IUPAC) name for OH A) B) C) D) E) Ans: p-Hydroxyphenol p-Dihydroxybenzene Resorcinol 1,4-dihydroxybenzene 1,4-Benzenediol E Topic: Nomenclature 6. What is the systematic (IUPAC) name for OH NO2 A) B) C) D) E) Ans: m-Hydroxy-p-nitrotoluene 3-Hydroxy-4-nitrotoluene 5-methyl-2-nitrophenol 3-methyl-2-nitrophenol 2-Hydroxy-4methylnitrobenzene C Topic: Nomenclature 7. What is the systematic (IUPAC) name for OH Br O A) B) C) D) E) Ans: p-Hydroxy-m-bromoacetophenone m-bromo-p-hydroxypropiophenone 3-bromo-4-hydroxypropiophenone 2-bromo-4-propanoylphenol 2-hydroxy-5-propanoylbromobenzene D 785 Chapter 21 Topic: Nomenclature 8. Which of the following is 5-bromo-3-methyl-1-naphthol? OH OH OH Br Br Br I II III OH HO Br Br IV A) B) C) D) E) Ans: V I II III IV V B Topic: Acid/Base 9. Which of the following phenols would have the largest pKa? F HO O2 N OH CH3 OH I II III OH OH Cl IV A) B) C) D) E) Ans: V I II III IV V C 786 Chapter 21 Topic: Acid/Base 10. Which of the following phenols would have the smallest pKa? NO2 O HO O OH OH I O II III O NH2 OH HO IV A) B) C) D) E) Ans: V I II III IV V C Topic: Acid/Base 11. Which of the following substances would have the smallest pKa? NO2 O HO O OH OH I O III II NH2 OH OH HO IV A) B) C) D) E) Ans: O V I II III IV V E 787 Chapter 21 Topic: Acid/Base 12. Which of the following compounds would you expect to be the strongest acid? A) CH3OH B) C6H5CH2OH C) p-CH3C6H4OH D) C6H5OH E) p-NO2C6H4OH Ans: E Topic: Acid/Base 13. Which compound would be most acidic? A) Cyclohexanol B) 1-Hexanol C) Phenol D) 4-Methylphenol E) 4-Chlorophenol Ans: E Topic: Acid/Base 14. Which of the following would be the strongest acid? HO HO CH3 OH I III II OH OH F3C Br IV A) B) C) D) E) Ans: V I II III IV V D 788 Chapter 21 Topic: Acid/Base 15. Which of the following would be the strongest acid? O Br OH OH OH I O III II SO3H OH OH HO IV A) B) C) D) E) Ans: V I II III IV V D Topic: Acid/Base 16. Which would be soluble in aqueous sodium bicarbonate? A) Benzoic acid B) 4-Methylphenol C) 2,4-Dinitrophenol D) More than one of these E) All of these Ans: D Topic: Acid/Base 17. Which reagent will distinguish between C6H5OH and C6H5CH2OH? A) NaHCO3 (aq) B) NaOH (aq) C) H2SO4 D) A) and B) E) B) and C) Ans: B 789 Chapter 21 Topic: Acid/Base 18. Which reagent will distinguish between C6H5OCH3 and p-CH3C6H4OH? A) NaOH (aq) B) NaHCO3 (aq) C) H2CrO4 D) A) and B) E) None of these Ans: A Topic: Acid/Base 19. Which compound reacts most rapidly with CH3ONa? Br Br NO2 Br NO2 I III II NO2 Br Br O2 N O2N IV A) B) C) D) E) Ans: NO2 V I II III IV V D 790 Chapter 21 Topic: Acid/Base 20. Which of these species is the strongest base? O O O H3C I Cl II III O O O2N I IV A) B) C) D) E) Ans: V I II III IV V B Topic: Reaction Products 21. Indicate the correct product, if any, of the following reaction. HO HBr Br Br HO HO Br Br HO Br I A) B) C) D) E) Ans: II III I II III IV There is no net reaction. E 791 Br Br IV Chapter 21 Topic: Reaction Products 22. Refluxing anisole, CH3OC6H5, with excess concentrated HBr would yield which of these product mixtures? A) C6H5Br + CH3OH B) C6H5OH + CH4 C) C6H5OH + CH3OH D) C6H5Br + CH3Br E) C6H5OH + CH3Br Ans: E Topic: Reaction Products 23. What product(s) would you expect from the following reaction? Cl F3C NaNH2 NH3(l), -33oC NH2 alone I A) B) C) D) E) Ans: F3C NH2 F3C F3C alone NH2 III II I II III Substantial amounts of I and II Substantial amounts of I, II, and III B 792 alone Chapter 21 Topic: Reaction Products 24. What product(s) would you expect from the following reaction? Br i. NaOH, NaHCO3, ? H2O, heat NO2 O2N ii. H3O + Br HO NaO NO2 O2N I A) B) C) D) E) Ans: NO2 O2N HO NH2 III II I II III Substantial amounts of I and II Substantial amounts of I, II, and III A Topic: Reaction Products 25. What would be the major product of the following reaction? HO Br2 (excess) ? H2O Br Br Br HO HO HO Br Br I A) B) C) D) E) Ans: II HO III I II III IV A mixture of I and II D 793 Br IV Chapter 21 Topic: Reaction Products 26. What products would you expect from the following reaction? i. OH−/ H2O, 400oC ? 4-Chlorotoluene ii. H3O+ A) B) C) D) E) Ans: 2-Methylphenol 3-Methylphenol 4-Methylphenol A) and B) B) and C) E Topic: Reaction Products 27. What is the major product of the following reaction? i) conc H2SO4,100oC Phenol ? ii) HNO3 / H2SO4, heat iii) H3O+/H2O, heat, steam distill A) B) C) D) E) Ans: p-Hydroxybenzenesulfonic acid p-Nitrophenol o-Nitrophenol 4-Hydroxy-3-nitrobenzenesulfonic acid 2-Hydroxy-4-nitrobenzenesulfonic acid C Topic: Reaction Products 28. Which products would be formed in the following reaction? OCH3 H3C A) B) C) D) E) Ans: conc HBr (excess) heat ? Methoxybenzene + methyl bromide 2-Methylphenol + methyl bromide 2-Bromotoluene + methanol 2-Bromotoluene + methyl bromide Bromobenzene + methyl bromide B 794 Chapter 21 Topic: Reaction Products 29. What is the final product? Phenol t-butyl chloride AlCl3 i. NaOH C10H14O (para-isomer) ii. CH3CH2I A) 1-tert-Butyl-4-ethoxybenzene B) 1-tert-Butyl-4-ethylbenzene C) 1-tert-Butoxy-4-ethoxybenzene D) tert-Butyl ethyl ether E) 1-tert-Butoxy-3-ethylbenzene Ans: A ? Topic: Reaction Products 30. What products(s) would you expect from the following reaction? Cl H3C NaNH2 NH3(l), -33oC ? NH2 H3C NH2 H3C alone I A) B) C) D) E) Ans: alone NH2 III II I II III Products I and II All of the above D Topic: Reaction Products 31. What is the product of the following synthesis? 1. H2SO4, 100oC phenol ? 2. 2 equiv Br2, H2O 3. dil. H2SO4, heat A) B) C) D) E) Ans: H3C 2,3-Dibromophenol 2,4-Dibromophenol 2,6-Dibromophenol 2-Hydroxy-3,5-dibromobenzenesulfonic acid 2,4,6-Tribromophenol C 795 alone Chapter 21 Topic: Reaction Products 32. What is the IUPAC name of the final product obtained via the following reaction sequence? 1. 2-bromopropane, AlCl3 2-bromophenol ? 2. NaOH 3. (CH3CO)2O A) 1-isopropyl-3-bromo-4-acetylbenzene B) 2-bromo-4-isopropyl -acetophenone C) 3-bromo-1-isopropyl-4-phenyl acetate D) (2-bromo-4-isopropyl)phenyl acetate E) None of the above correctly describes the product Ans: D Topic: Reaction Products 33. What is the IUPAC name of the final product obtained via the following reaction sequence? 2-bromophenol 1. CH3I, base ? 2. Butanoyl chloride, AlCl3 3. Zn(Hg), HCl 4. conc HBr, heat A) 1-butanoyl-3-bromo-4-methoxybenzene B) 2-bromo-4-butylphenol C) 3-bromo-1-butyl-4-methoxybenzene D) 3,4-dibromo-1- butanoylbenzene E) None of the above correctly describes the product Ans: B Topic: Reaction Products 34. What is the IUPAC name of the final product obtained via the following reaction sequence? 1. H2, Ni 2-nitrophenol ? 2. NaNO2, HCl, 0-5oC 3. KI 4. Br2, 5oC, CS2 A) 4-bromo-2-iodophenol B) 2-bromo-4-iodophenol C) 2,4-dibromophenol D) 2,4-dibromo-6- iodophenol E) 1-bromo-3-iodobenzene Ans: A 796 Chapter 21 Topic: Reaction Products 35. What is the final product obtained via the following reaction sequence? 1. NBS 1-ethyl-4-methoxybenzene ? 2. Mg, Et2O 3. (CH3)2C=O 4. H3O+ 5. conc HBr, heat Br OH H3CO HO OCH3 OCH3 I II III Br OH HO IV A) B) C) D) E) Ans: V I II III IV V E 797 Chapter 21 Topic: Reaction Products 36. What product should be obtained if benzyne is generated in the presence of 1,3butadiene? I II III IV A) B) C) D) E) Ans: V I II III IV V A Topic: Reaction Products 37. Which product is likely to be obtained during the following reaction of the isotopelabeled allyl ether (14C-isotopic site marked with an asterisk)? O 200oC * O OH * OH * I III II OH OH * * IV A) B) C) D) E) Ans: ? V I II III IV V B 798 * Chapter 21 Topic: Reaction Products 38. When sodium phenoxide is heated to 125°C with carbon dioxide under pressure and the product mixture acidified, which of these is produced? O OH O O OH O HO OH I II O III OH O OH OH HO IV A) B) C) D) E) Ans: OH V I II III IV V B 799 Chapter 21 Topic: Reaction Products 39. What product is likely to be obtained by the action of Ag+ or Fe+3 on the following substance? OH CH3 Ag+ or Fe3+ ? OH O OH O CH3 O O O O OH O I II III O OH CH3 HO H IV A) B) C) D) E) Ans: O CH3 O V I II III IV V A 800 Chapter 21 Topic: Reaction Products 40. What is the product of the reaction of 1 mol of p-benzoquinone with 1 mol of isoprene (2-methyl-1,3-butadiene)? O O O O I O III II O O O O IV A) B) C) D) E) Ans: O V I II III IV V A 801 Chapter 21 Topic: Reaction Products 41. What are the products of the reaction of phenol with propanoic anhydride in the presence of base? O O O O O + + CH3CH2CO2 − O + CH3CH2CO2− I CH3CH2CO2− II III O O + CH3CH2CO2− IV A) B) C) D) E) Ans: + CH3CH2CH2OH V I II III IV V C 802 Chapter 21 Topic: Reaction Products 42. What is the product of the reaction of phenol and chloroacetic acid in basic solution, followed by acidification? O Cl O OH O OH Cl O O I II OH O III OH OH O O IV A) B) C) D) E) Ans: V I II III IV V D 803 Chapter 21 Topic: Reaction Products 43. Predict the product of this Cope rearrangement: o C6H5 180 C ? C6H5 C6H5 C6H5 I II C6H5 III C6H5 IV A) B) C) D) E) Ans: V I II III IV V C Topic: Reaction Products 44. What product is likely to be obtained when 1-bromo-2-nitrobenzene is heated with aqueous NaHCO3? A) 2-bromophenol B) 2-nitrophenol C) 2-bromophenyl carbonate D) 2-nitrophenyl carbonate E) Sodium 2-nitrophenoxide Ans: E Topic: Reaction Products 45. What product is likely to be obtained when 1-chloro-3-nitrobenzene is heated with aqueous NaHCO3? A) 3-chlorophenol B) 3-nitrophenol C) 3-chlorophenyl carbonate D) Sodium 2-nitrophenoxide E) None of the above: no reaction is likely to occur Ans: E 804 Chapter 21 Topic: Reaction Products 46. What product is likely to be obtained when 1-fluoro-2,4-dinitrobenzene is treated with sodium ethoxide? A) 2,4-dinitrophenol B) 1-ethoxy-2,4-dinitrobenzene C) 2,4-diethoxy-1-fluorobenzene D) 2,4-dinitrophenylsodium E) None of the above: no reaction is likely to occur Ans: E Topic: Reaction Products 47. What product is likely to be obtained when 1-chloro-2-trifluoromethylbenzene is treated with sodium amide in liquid ammonia? A) 2-(trifluoromethyl)aniline B) 3-(trifluoromethyl)aniline C) 4-(trifluoromethyl)aniline D) 2-chloroaniline E) None of the above: no reaction is likely to occur Ans: B Topic: Synthesis 48. Which of the following would provide a synthesis of aspirin, o-CH3COOC6H4COOH ? A) C6H5COOH, CH3COOH, AlCl3, heat; then H2O B) CH3COOC6H5, CO2, heat; then H3O+ C) CH3COOC6H5, HCOOC2H5, C2H5O-; then H3O+; then OHD) C6H5OH, CO2, H3O+; separate isomers; then CH3COOH, AlCl3 E) C6H5OH, OH-, CO2, heat, pressure; then H3O+; then (CH3CO)2O Ans: E Topic: Synthesis 49. Identify the commercial preparation(s) of phenol. A) Chlorobenzene + NaOH at 350°C; then H3O+ B) Benzene + O2 C) C6H5CH(CH3)2 + O2; then H3O+, heat D) A) and B) E) A) and C) Ans: E 805 Chapter 21 Topic: Synthesis 50. Which method could be used for preparing methoxybenzene from phenol? A) NaOH, then CH3I B) NaOH, then CH3OSO2CH3 C) NaOH, then CH3OCH3 D) More than one of these E) All of these Ans: D Topic: Synthesis 51. Which of these is an acceptable synthesis of phenetole (ethyl phenyl ether)? A) CH3CH2ONa Chlorobenzene 100oC B) C) Sodium phenoxide Sodium phenoxide CH3CH2I 70oC (CH3CH2O)2SO2 o 100 C D) Phenol CH3CH2OH, H2SO4 70oC E) More than one of these Ans: E Topic: Synthesis 52. Which of the following reactions would yield p-tert-butylphenol? A) H3O+ Phenol + Phenol + OH H3O+ Phenol + Cl AlCl3 B) C) D) All of these E) None of these Ans: D 806 Chapter 21 Topic: Synthesis 53. Which of these is a satisfactory method for the preparation of m-nitrophenol from benzene? A) i) HNO3 / H2SO4; ii) Sn / HCl; iii) NaNO2, H2SO4, H2O, 0-5oC; iv) Cu2O, Cu2+, H2O; v) HNO3 iv) H3O+ B) i) Cl2, Fe; ii) HNO3 / H2SO4; iii) NaOH, H2O; C) i) HNO3/H2SO4; ii) Cl2, Fe; iii) NaOH, H2O; D) i) 2 HNO3 / 2 H2SO4; ii) NH3, H2S; iii) NaNO2, H2SO4, H2O, 0-5oC; iv) Cu2O, Cu2+, H2O E) i) HNO3 / H2SO4; ii) NaOH / fusion; iii) H3O+ Ans: D Topic: Synthesis 54. Which of these reactions does not produce phenol? A) i. NaOH, H2O O O ii. H3O+ H3O+ B) ONa C) O HI D) Cl H2O NH2 100oC i. NaNO2, H2SO4, H2O, 0-5oC E) ii. Cu2O, Cu2+, H2O Ans: D 807 iv) H3O+ Chapter 21 Topic: Relative Reactivities and General Considerations 55. Which of the following would be most likely to undergo a nucleophilic substitution reaction with aqueous sodium hydroxide by an addition-elimination mechanism? Br Br Br O O I II III Br NO2 Br NO2 IV A) B) C) D) E) Ans: O2N NO2 V I II III IV V D Topic: Relative Reactivities and General Considerations 56. In terms of reactivity towards nucleophiles, bromobenzene is most similar to which of these? A) Allyl bromide B) Vinyl bromide C) tert-Butyl bromide D) Propyl bromide E) Methyl bromide Ans: B Topic: Relative Reactivities and General Considerations 57. In nucleophilic aromatic substitution, the attacking species (the nucleophile) necessarily is: A) A Lewis base B) Neutral C) Positively charged D) Negatively charged E) Electron deficient Ans: A 808 Chapter 21 Topic: Relative Reactivities and General Considerations 58. Which of the following substances readily undergoes ring bromination with Br2, even in the absence of a Lewis acid catalyst? A) 2,4-Dinitrotoluene B) 2,4-Dimethylbenzoic acid C) 3-Nitroaniline D) 4-Bromophenyl acetate E) 1,3-benzenediol Ans: D Topic: Relative Reactivities and General Considerations 59. Which is the leaving group when the following substance reacts with sodium cyanide in DMSO solution? I Br VH Br II H III NO2 A) B) C) D) E) Ans: IV I II III IV V A Topic: Relative Reactivities and General Considerations 60. Which position is predicted to be the chief site of substitution when the following substance reacts with bromine in carbon disulfide at 10°C ? II HO A) B) C) D) E) Ans: III IV V I CH3 I II III IV V A 809 Chapter 21 Topic: Relative Reactivities and General Considerations 61. Which of these resonance structures makes the greatest contribution to the hybrid for the intermediate in the SNAr reaction of o-chloronitrobenzene with methoxide ion? H3CO Cl O H3CO Cl O H3CO O O II H3CO Cl O N O I III O H3CO Cl N O N O O IV A) B) C) D) E) Ans: Cl N N V I II III IV V E Topic: Relative Reactivities and General Considerations 62. The formation of equal amounts of m-toluidine (m-aminophenol) and p-toluidine in the reaction of p-bromotoluene with sodium amide in liquid ammonia at -33°C suggests this species as the reaction intermediate: Br NH2 Br NH2 II I IV A) B) C) D) E) Ans: III V I II III IV V D 810 Chapter 21 Topic: Relative Reactivities and General Considerations 63. Phenol is less reactive than expected in Friedel-Crafts acylations for which of these reasons? A) The acid chloride or anhydride hydrolyzes under the reaction conditions. B) The electronegativity of the -OH group reduces the reactivity of phenol. C) Interaction of the -OH group with AlCl3 forms a species less reactive than phenol. D) The reaction gives O-acylation only, resulting in an ester. E) The aromatic ring complexes with AlCl3 with a resulting decrease in phenol reactivity. Ans: C Topic: Spectroscopic Analysis 64. Thymol, isolated from thyme, has the following structure: OH Which of the following types of signal is NOT expected to be observed in its NMR spectrum? A) singlet B) doublet C) triplet D) septet E) all of the above types of signals are expected to be observed Ans: C Topic: Spectroscopic Analysis 65. Methyl salicylate, commonly found in topical muscle relaxants, has the following structure: OH O O Which of the following signals is NOT expected to be observed in its NMR spectrum? A) Singlet at ~4 ppm (3H) B) Doublet at ~7 ppm (1H) C) Quartet at about 7 ppm (4H) D) Singlet at ~ 6 ppm (1H) E) Two of the above types of signals are not expected to be observed Ans: C 811 Chapter 21 Topic: Spectroscopic Analysis 66. Eugenol, isolated from cloves, has the following structure: OH O Which of the following signals is NOT expected to be observed in its NMR spectrum? A) Singlet at ~4 ppm (3H) B) Doublet at ~2.5 ppm (2H) C) Singlet at ~ 7 ppm (1H) D) Singlet at ~ 6 ppm (1H) E) All of the above types of signals are expected to be observed Ans: E Topic: Structure Identification 67. Compound L has the molecular formula C11H16O. L is insoluble in water but dissolves in aqueous NaOH. The infrared spectrum of L shows a broad absorption band in the 3200-3600 cm-1 region; its 1H NMR spectrum consists of: triplet, singlet, quartet, singlet, multiplet, δ 0.80 δ 1.2 δ 1.5 δ 4.5 δ 7.0 (6H) (1H) (4H) The most likely structure for compound L is: HO HO II I O III HO IV A) B) C) D) E) Ans: O V I II III IV V E 812 Chapter 21 SHORT ANSWER QUESTIONS Topic: Synthesis 68. The most important laboratory synthesis of phenols is by _______________. Ans: hydrolysis of arenediazonium salts Topic: Claisen, Cope Rearrangement 69. The Claisen and Cope rearrangements are two examples of a general class of reactions called ___________. Ans: pericyclic reactions Topic: General 70. The carbon-halogen bonds in aryl and vinyl halides are both __________ and _____________ than the corresponding bonds in alkyl halides. Ans: shorter; stronger Topic: General, Nucleophilic Aromatic Substitution 71. Nucleophilic aromatic substitution reactions (SNAr) take place via a delocalized carbanion intermediate called a ______________. Ans: Meisenheimer complex Topic: General, Nucleophilic Aromatic Substitution 72. Nucleophilic aromatic substitution reactions (SNAr) require three components: a good leaving group on the aromatic ring, a strong nucleophile, and ________________. Ans: an electron-withdrawing substituent ortho or para to the leaving group Topic: General, Nucleophilic Aromatic Substitution 73. In general, there are two types of nucleophilic aromatic substitution mechanisms. These are: ______________. Ans: addition-elimination or SNAr; elimination-addition or benzyne Topic: Benzyne Intermediate 74. Benzyne is a very unstable intermediate, because _____________. Ans: the two carbons involved in the extra π bond are sp hybridized, causing a severe amount of bond angle distortion and strain Topic: Nomenclature 75. The commonly used name for hydroxybenzene is __________. Ans: phenol Topic: Industrial Synthesis 76. Most of the worldwide industrial preparation of phenol is now based on the ___________. Ans: cumene hydroperoxide method 813 Chapter 21 Topic: Industrial Synthesis 77. The cumene hydroperoxide synthesis of phenol is industrially very satisfying, because it takes two inexpensive starting materials, ___________ and ___________, and converts them into two valuable products, phenol and __________. Ans: benzene; propene; acetone Topic: Nomenclature 78. Draw the structure corresponding to the following IUPAC name: (2E,4S)-4-(3-hydroxyphenyl)-2-pentenoic acid Ans: H3C H OH O OH Topic: Nomenclature 79. Draw the structure corresponding to the following IUPAC name: (R)-2-Bromo-5-(3-methylpentyl)phenol H CH3 Ans: Br OH Topic: Nomenclature 80. Draw the structure corresponding to the following IUPAC name: 4-benzyl-3,5-diiodophenol I Ans: HO I Topic: Nomenclature 81. Give the IUPAC name of the following substance: H3C H O HO O Ans: (R)-methyl 6-(4-hydroxyphenyl)-4-methylhexanoate 814 Chapter 21 Topic: Relative Acidity 82. Draw the structure of the ionic species obtained when the following substance is treated with NaOH: NH2 OH HO Ans: − NH2 O Na + HO Topic: Chemical Analysis, Relative Acidity 83. Suggest a simple chemical test to distinguish between 4-methylphenol and 2,4,6trinitrophenol, briefly explaining your rationale. Ans: Both substances will dissolve in aq NaOH via an acid-base reaction. However, only 2,4,6-trinitrophenol, being significantly more strongly acidic, is likely to react with aq NaHCO3, releasing gaseous CO2 (easily observed as effervescence). The differences in reactivity can be attributed to the fact that nitro groups are strongly electron-withdrawing, while the methyl group is weakly electrondonating. NO2 OH OH O2N NO2 stronger acid gives CO2 with NaHCO3(aq) weaker acid no reaction with NaHCO3(aq) Topic: Reaction Product 84. Draw the structure of the product obtained when benzoquinone reacts with 2 molar equivalents of 1,3-butadiene via a Diels Alder reaction. O Ans: O Diels Alder + Reaction O 1 mol O 2 mol 815 Chapter 21 Topic: Reaction Product 85. Draw the structure of the product obtained when the following substance is heated strongly: O O Ans: OH heat (Claisen Rearrangement) Topic: Reaction Product 86. Draw the structure of the final product obtained when 2-nitrophenol reacts with acetic anhydride in presence of base. O O Ans: NO2 NO2 OH O O O base Topic: Reaction Product 87. Draw the structure of the final product obtained when 1-chloro-2,4-dinitrobenzene is heated with aqueous NaHCO3 at 100oC, followed by neutralization with H3O+ . NO2 NO2 Ans: OH Cl i. NaHCO3 (aq), 100oC + ii. H3O O N O N 2 2 Topic: Reaction Product 88. Draw the structure of the final product obtained when 3-methylphenol is subjected to the following reaction sequence: i) NaOH; ii) CH3CH2CH2OSO2OCF3 Ans: OH O i) NaOH ii) CH3CH2CH2OSO2OCF3 Topic: Reaction Sequence 89. Draw the structure of the final product obtained when 4-cyclopentylphenol is subjected to the following reaction sequence: i) NaOH; ii) CH3I; iii) NBS; iv) CH3ONa/CH3OH, heat OH O Ans: i) NaOH ii) CH3I iii) NBS iv) CH3ONa, CH3OH, heat 816 Chapter 21 Topic: Synthesis 90. The insecticide Sevin is synthesized from 1-naphthol and methyl isocyanate (CH3-N=C=O). Draw the structure of this insecticide. O Ans: OH N H O + CH3-N=C=O Sevin Topic: Synthesis 91. Orange II is an azo dye made from 2-naphthol and the diazonium salt of paminobenzenesulfonic acid. Indicate the synthetic steps involved in this synthesis and draw the structure of Orange II. NaNO2 Ans: SO3H 0-5oC H2N SO3H H2SO4 − Cl+N2 OH N OH N SO3H OrangeII Topic: Synthesis 92. Draw the structure of the product likely to be obtained from the reaction between acetoacetic ester, bromobenzene and 2 molar equivalents of sodium amide (in liquid ammonia)? Briefly explain your rationale. Ans: This is likely to be a benzyne mediated (elimination-addition mechanism) nucleophilic substitution reaction of bromobenzene. 1 equivalent of sodium amide is likely to promote elimination to form benzyne, while the 2nd equivalent of base would generate the anion of acetoacetic ester, which can then react with the benzyne to give the following product. O O O 817 Chapter 21 Topic: Synthesis 93. Outline the steps involved in the synthesis of 3-bromo-4-methylphenol from 4nitrotoluene Ans: i. Br2, FeBr3 ; ii) Fe, HCl; iii) NaNO2, H2SO4, 0-5oC; iv) Cu2O, Cu2+, H2O Br NO2 OH 3-bromo-4-methylphenol 4-nitrotoluene Br NO2 Br Br2 FeBr3 NO2 Fe HCl NH2 4-nitrotoluene i. NaNO2, H2SO4 0-5oC ii. Cu2O, Cu2+, H2O Br OH 3-bromo-4-methylphenol 818 Chapter 21 Topic: Industrial Synthesis 94. A key step in the industrial synthesis of phenol from cumene is the oxidation of cumene to cumene hydroperoxide with oxygen. Outline the mechanistic steps that lead to this oxidation product. O2 O OH 95-135oC cumene hydroperoxide cumene Ans: This is a radical chain reaction. A radical initiator is required to initiate the process, which begins with abstraction of the benzylic hydrogen to produce a 3o radical. The ensuing chain reaction leads to the formation of cumene hydroperoxide. Initiation Step 1 H + R. . + R−H cumene Propagation Step 2 + . O-O . . O O. Step 3 O O. + H O OH + cumene hydroperoxide 819 . Chapter 21 Topic: Industrial Synthesis 95. The industrial synthesis of phenol from cumene involves the acid hydrolysis of the key intermediate, cumene hydroperoxide (formed from cumene via oxidation). Outline the mechanistic steps that lead to this oxidation product. Which other industrially important substance is produced as a by-product in this reaction? H3O+ O OH OH 50-90oC cumene hydroperoxide phenol Ans: This is a hydrolytic rearrangement reaction. Protonation of the –OH group of cumene hydroperoxide, leads to a 1,2-phenyl migration with concomitant loss of water. Nucleophilic addition to the resultant carbocation ultimately leads to the formation of phenol. Another industrially important substance, acetone, is formed as a by-product during this reaction, making this a doubly attractive synthetic strategy. H3O+ O OH OH + O 50-90oC cumene hydroperoxide O OH phenol H3O+ O OH2 + - H2O acetone + cumene hydroperoxide O - H3O+ + HO acetone O H2O HO H O + phenol 820 + H2O O Chapter 21 Topic: Synthesis 96. Suggest a reasonable synthetic strategy for the synthesis of 3-bromophenol from acetophenone Ans: i) Br2, FeBr3; ii) MCPBA; iii) H3O+ Br OH O acetophenone 3-bromophenol Br O Br2 FeBr3 Br O MCPBA O O H3O+ heat acetophenone Br OH 3-bromophenol 821 Chapter 21 Topic: Synthesis, Separation of (o-, p-) Products 97. When phenol is nitrated with dilute nitric acid, a mixture of o- and p- substituted products is obtained. These products can then be separated by the technique of steam distillation. However, analogous products from the nitration of methoxybenzene cannot be similarly separated by steam distillation. Explain. Ans: In order for efficient separation of substances (from a mixture) by steam distillation, there must be relatively large differences in volatility. The more volatile substance passes over with the steam, leaving the less volatile substance in the distillation flask. Differences in the volatility of the o- and p- nitrophenols may be predicted by considering hydrogen bonding effects: o-nitrophenol can exhibit intramolecular hydrogen bonding, while p-nitrophenol can exhibit intermolecular hydrogen bonding. Consequently, o-nitrophenol is likely to be significantly more volatile than p-nitrophenol, leading to the possibility of efficient separation by steam distillation. By contrast, since no hydrogen bonding is possible in the products obtained by nitration of methoxybenzene, there is no predictable difference in volatility. Hence, these products cannot be separated by steam distillation. O O N H O O O N O N H O O o-nitrophenol intramolecular hydrogen bonding more volatile OCH3 methoxybenzene O H p-nitrophenol intermolecular hydrogen bonding less volatile OCH3 + O2N OCH3 NO2 no hydrogen bonding in either product: volatility differences not likely to be significant 822 Chapter 21 Topic: Synthesis 98. Outline the steps involved in the synthesis of 3-nitrophenol from 1,3-dinitrobenzene Ans: i) NH3, H2S, EtOH; ii) NaNO2, H2SO4, 0-5oC; iii) Cu2O, Cu2+, H2O O2N O2N NO2 OH 1,3-dinitrobenzene O2 N 3-nitrophenol O2N NO2 o NH3 H 2S EtOH NH2 O2N i) NaNO2, H2SO4, 0-5 C OH ii) Cu2O, Cu2+, H2O Topic: Synthesis, Hofmann/Curtius Rearrangement 99. Outline the steps involved in the synthesis of 3-nitrophenol from benzoic acid Ans: i) HNO3, H2SO4 ; ii) SOCl2; iii) NH3; iv) Br2, NaOH; v) NaNO2, H2SO4, 0-5oC; vi) Cu2O, Cu2+, H2O or i) HNO3, H2SO4 ; ii) SOCl2; iii) NaN3; iv) heat; v) H2O; vi) NaNO2, H2SO4, 0-5oC; vii) Cu2O, Cu2+, H2O O2N CO2H OH 3-nitrophenol benzoic acid O O OH HNO3 H2SO4 O OH O Cl SOCl2 NO2 NH2 NH3 NO2 NO2 i) NaN3 ii) heat iii) H2O Br2 NaOH OH NH2 o i) NaNO2, H2SO4, 0-5 C NO2 ii) Cu2O, Cu2+, H2O 3-nitrophenol 823 NO2 Chapter 21 Topic: Synthesis, Grignard Synthesis 100. Outline the steps involved in the synthesis of p-methoxybenzoic acid from phenol. Ans: i) NaOH ; ii) CH3I; iii) Br2, FeBr3 ; iv) Mg, Et2O; v) CO2; vi) H3O+ OH OH O O p-methoxybenzoic acid phenol OH O i) NaOH ii) CH3I O O i) Mg, Et2O Br2 FeBr3 ii) CO2 Br iii) H3O+ (+ o- isomer) 824 O OH Chapter 22 MULTIPLE CHOICE QUESTIONS Topic: Nomenclature, Definitions and Types of Carbohydrates 1. An aldaric acid is represented by: HO HO H H CHO H H OH OH CH2OH HO HO H H I A) B) C) D) E) Ans: CO2H H H OH OH CH2OH HO HO H H II CO2H H H OH OH CO2H HO HO H H III CH2OH H H OH OH CH2OH HO HO H H IV CHO H H OH OH CO2H V I II III IV V C Topic: Nomenclature, Definitions and Types of Carbohydrates 2. Epimers are represented by: CH2OH O HO H H H OH OH CH2OH H HO H H I A) B) C) D) E) Ans: CHO OH H OH OH CH2OH II HO HO H H CHO H H OH OH CH2OH III I and II II and III I, II, and III III and IV I, II, and V B 825 H H HO HO CHO OH OH H H CH2OH IV HO HO HO HO CHO H H H H CH2OH V Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 3. Which is a ketohexose? A) D-Glucose B) D-Fructose C) D-Mannose D) D-Ribose E) (+)-Sucrose Ans: B Topic: Nomenclature, Definitions and Types of Carbohydrates 4. Which of these compounds, I, II, III, IV, is a reducing disaccharide? H OH CH2OH O H OH H H CH2OH H H O OH O H OH H H H H OH OH OH CH2OH O H OH H H H OH H H H O OH H OH II CH2OH O H H OH H OCH3 H H OH OH CH2OH O H OH H H III A) B) C) D) E) Ans: O OH I CH2OH O H OH H H H CH2OH O H H OH H OH OH O OH 826 H OH H H IV I alone II alone III alone IV alone I, II, III, and IV B O H OH CH2OH Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 5. Sugars that undergo mutarotation in neutral aqueous solution are: CH2OH O H H H OH H OH OH H CH2OH O OH H H OH H H OH OH H I H OH OH H II CH2OH O H OH H H CH2OH O H H H OH H OCH3 OH CH2OH H H O O H OH H OH H H H OH OH OH CH2OH O H OH H H H H O CH2OH O H H OH H OH OH IV A) B) C) D) E) Ans: OH III H OH V I and III III and IV II, III, and IV I and IV I, II, and V E Topic: Nomenclature, Definitions and Types of Carbohydrates 6. Which of the following is an L-aldotetrose? CHO H OH H OH CH2OH I A) B) C) D) E) Ans: CHO HO H H OH CH2OH CHO H OH HO H CH2OH CO2H H OH HO H CH2OH CH2OH H OH HO H CO2H II III IV V I II III IV V C 827 Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 7. Which of the following is a D-aldotetrose? H H CHO OH OH CH2OH I HO H CO2H H OH CH2OH II A) B) C) D) E) Ans: H HO CHO OH H CH2OH III H HO CH2OH OH H CH2OH IV HO HO CHO H H CH2OH V I II III IV V A Topic: Nomenclature, Definitions and Types of Carbohydrates 8. An aldonic acid is represented by: HO HO H H CO2H H H OH OH CH2OH I A) B) C) D) E) Ans: HO HO H H CH2OH H H OH OH CH2OH II HO HO H H CO2H H H OH OH CO2H III I II III IV V A 828 HO HO H H CHO H H OH OH CO2H IV HO HO H H CO2H H H OH OH CHO V Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 9. Which of the following is an L-aldopentose? CHO H OH H OH CH2OH H H HO I CHO OH OH H CH2OH CHO H OH HO H CH2OH II A) B) C) D) E) Ans: HO HO H III CH2OH O C HO H HO H CH2OH CHO H H OH CH2OH IV V I II III IV V B Topic: Nomenclature, Definitions and Types of Carbohydrates 10. Which compound is D-galactose? CH2OH O OH OH H H H H H CH2OH O H H H OH H OH OH OH OH H I OH H II CH2OH O H H H H H OH OH OH III CH2OH O H OH H OH OH OH H OH OH H IV A) B) C) D) E) Ans: CH2OH O H OH H OH H H OH H V I II III IV V C 829 Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 11. Which of these is ∝-D-glucopyranose? CH2OH O OH OH CH2OH O CH2OH O OH OH OH OH OH OH I OH II CH2OH O OH OH OCH3 III OH CH2OH O OH OH OH OH IV A) B) C) D) E) Ans: OH OH V I II III IV V A 830 OH OH Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 12. Which of these is a non-reducing monosaccharide? CH2OH O OH OH CH2OH O CH2OH O OH OH OH OH OH OH OH I OH II CH2OH O OH OCH3 III HOH2C O HO OH OH OH IV A) B) C) D) E) Ans: OH V I II III IV V D 831 OH CH2OH OH Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 13. Which of these is a glycoside? CH2OH O OH OH CH2OH O OH OH OH OH CH2OH O OH OH OH I OH II CH2OH O OH OCH3 III OH CH2OCH3 O OH OH OH OH OH IV A) B) C) D) E) Ans: OH V I II III IV V D 832 OH Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 14. Which are the anomers? CH2OH O OH OH CH2OH O OH OH OH OH OH OH I II CH2OH O CH2OH O OH OH OH OH III A) B) C) D) E) Ans: OH OH OH OH IV I and II I and III II and III II and IV III and IV B 833 Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 15. Consider the structures shown below. Which structure represents β-D-glucopyranose? OH HO OH O HO HO O HO OH OH OH OH I II OH HO OH O HO HO OH O OH OH OH III IV OH O HO HO OH OCH3 V A) B) C) D) E) Ans: I II III IV V C 834 OH Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 16. Consider the structures shown below. Which compound is not a reducing sugar? OH HO OH O HO HO O HO OH OH OH OH I II OH HO OH O HO HO O OH OH OH OH OH III IV OH O HO HO OH OCH3 V A) B) C) D) E) Ans: I II III IV V E Topic: Nomenclature, Definitions and Types of Carbohydrates 17. Which of the following is the structure of D-galacturonic acid? H HO HO H CH2OH OH H H OH CO2H I A) B) C) D) E) Ans: H HO HO H CO2H OH H H OH CH2OH II H HO HO H CHO OH H H OH CO2H III I II III IV V C 835 H HO HO H CO2H OH H H OH CO2H IV HO H H HO CHO H OH OH H CO2H V Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates, Analysis 18. Which is not likely to give a brick-red precipitate with Benedict’s solution? A) Maltose B) Cellobiose C) Sucrose D) Lactose E) None of these Ans: C Topic: Nomenclature, Definitions and Types of Carbohydrates 19. A glycoside is a compound which contains the structural features of these classes of organic compounds: A) Aldehydes and alcohols B) Acetals and alcohols C) Hemiacetals and alcohols D) Ketones and alcohols E) Alcohols and carboxylic acids Ans: B Topic: Nomenclature, Definitions and Types of Carbohydrates 20. Which of these is an example of a glucan? A) Maltose B) Sucrose C) Lactose D) Cellobiose E) Amylose Ans: E Topic: Nomenclature, Definitions and Types of Carbohydrates 21. Which is a reducing sugar with an ∝-glycosidic linkage? A) Sucrose B) Maltose C) Lactose D) Cellobiose E) None of these Ans: B 836 Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 22. Which compound will not reduce Ag(NH3)2+ ? OH OH O HO HO O HO HO OH OCH3 OH HOH2C OH CH2OH OH OH OH OH OH III O O HO CH2OH A) B) C) D) E) Ans: OH OH II CHO OH O HO I H O OH OH IV V I II III IV V A Topic: Nomenclature, Definitions and Types of Carbohydrates 23. What is the correct description of this disaccharide? CH2OH O O A) B) C) D) E) Ans: CH2OH O The ∝-anomer of two D-glucose units joined by an ∝(1→4) linkage The ∝-anomer of two D-galactose units joined by an ∝(1→4) linkage The β-anomer of two D-galactose units joined by a β(1→4) linkage The β-anomer of two D-glucose units joined by a β(1→4) linkage The ∝-anomer of two D-galactose units joined by a β(1→4) linkage E 837 Chapter 22 Topic: Nomenclature, Definitions and Types of Carbohydrates 24. What is a correct general description of the monosaccharide shown here? HOH2C O OH CH2OH OH OH A) B) C) D) E) Ans: The ∝-anomer of the pyranose form of an aldohexose The β-anomer of the pyranose form of an aldohexose The ∝-anomer of the furanose form of a ketohexose The β-anomer of the furanose form of a ketohexose The β-anomer of the furanose form of an aldohexose D Topic: Nomenclature, Definitions and Types of Carbohydrates 25. What can be said, correctly, about a monosaccharide, the name of which is preceded only by (+) ? A) The compound is the ∝-anomer. B) The compound exists in the pyranose form. C) The compound is dextrorotatory. D) The compound has the same stereochemistry at the penultimate carbon as D-(+)glucose. E) The compound exists only in open-chain form. Ans: C Topic: Nomenclature, Definitions and Types of Carbohydrates 26. How many stereoisomers of the L series would exist for the following pentose? O=CHCHOHCHOHCHOHCH2OH A) 2 B) 3 C) 4 D) 5 E) 8 Ans: C 838 Chapter 22 Topic: Reactions 27. Reaction of the following substance with sodium borohydride (NaBH4) would yield: HO HO H H CHO H H OH OH CH2OH HO HO H H CO2H H H OH OH CH2OH I A) B) C) D) E) Ans: NaBH4 HO HO H H CO2H H H OH OH CO2H II ? HO HO H H CH2OH H H OH OH CH2OH III I II III IV V C 839 HO HO H H CHO H H OH OH CO2H IV HO HO H H CH3 H H OH OH CH2OH V Chapter 22 Topic: Reactions 28. Reaction of the following substance with bromine water would yield: HO HO H H CHO H H OH OH CH2OH Br2 H2O HO HO H H CO2H H H OH OH CH2OH HO HO H H I A) B) C) D) E) Ans: ? CO2H H H OH OH CO2H II HO HO H H CH2OH H H OH OH CH2OH III I II III IV V A 840 HO HO H H CHO H H OH OH CO2H IV HO HO H H CHO H H OH OH CHO V Chapter 22 Topic: Reactions 29. If J (below) were treated with dilute aqueous hydrochloric acid and the solution allowed to stand, what compounds (other than methanol) would be formed in the solution? CH2OH O H dil HCl H H 2O OH H OCH3 HO H OH H CHO H H OH OH CH2OH HO HO H H A) B) C) D) E) Ans: HO HO H H I I and II I and III II and III I, III, and IV II, III, and IV D CHO H H OH OH CH2OH ? CH2OH O H H H OH H HO OH H OH II CH2OH O OH H OH H H HO H OH H III IV Topic: Reactions 30. A compound X reacts with 3 mol of HIO4 to yield 2 mol of HCO2H and 2 mol of HCHO. What is the structure of X? CH2OH CHO CHO CH2OH CHOH CHOH CHOH C O C O CHOH CHOH CHOH C O C O CH2OH CH2OH CHO CH2OH CHO I A) B) C) D) E) Ans: II III IV V I II III IV V A 841 CHO Chapter 22 Topic: Reactions 31. A D-aldohexose, X, is subjected to a Ruff degradation. The degradation product is treated with nitric acid to yield an optically inactive aldaric acid. A possible structure for X is: HO HO H H CHO H H OH OH CH2OH H H H H I A) B) C) D) E) Ans: CHO OH OH OH OH CH2OH HO H H HO II CHO H OH OH H CH2OH H HO HO H III CHO OH H H OH CH2OH H HO HO HO IV CHO OH H H H CH2OH V I II III IV V B Topic: Reactions 32. Which of the following would yield D-glucose and D-mannose when subjected to a Kiliani-Fischer synthesis? HO H H CHO H OH OH CH2OH I A) B) C) D) E) Ans: H H H CHO OH OH OH CH2OH II H H HO CHO OH OH H CH2OH III I II III IV V A 842 H HO H CHO OH H OH CH2OH IV HO HO H CHO H H OH CH2OH V Chapter 22 Topic: Reactions 33. Reaction of the following substance with nitric acid would yield: HO HO H H CHO H H OH OH CH2OH HO HO H H CO2H H H OH OH CH2OH HNO3 HO HO H H I A) B) C) D) E) Ans: CO2H H H OH OH CO2H ? HO HO H H II CH2OH H H OH OH CH2OH HO HO H H III CHO H H OH OH CO2H HO HO H H IV CO2H H H OH OH CHO V I II III IV V B Topic: Reactions 34. Which aldohexose would yield an optically active aldaric acid when treated with nitric acid? HO HO H H CHO H H OH OH CH2OH I A) B) C) D) E) Ans: H H H H CHO OH OH OH OH CH2OH II HO H H HO CHO H OH OH H CH2OH III I II III IV V A 843 H HO HO H CHO OH H H OH CH2OH IV HO HO HO HO CHO H H H H CH2OH V Chapter 22 Topic: Reactions 35. Which compound or compounds would be formed when D-glucose is dissolved in methanol and then treated with anhydrous acid? OCH3 OH O HO HO OCH3 OH O H3CO H3CO OCH3 I II OH OH O HO HO OCH3 OH O HO HO III A) B) C) D) E) Ans: OCH3 IV OH OCH3 I II III IV I and IV E Topic: Reactions 36. A D-aldohexose, Z, is subjected to a Ruff degradation. The degradation product is treated with nitric acid to yield an optically active aldaric acid. A possible structure for Z is: HO HO H H CHO H H OH OH CH2OH I A) B) C) D) E) Ans: H H H H CHO OH OH OH OH CH2OH HO H H HO II CHO H OH OH H CH2OH III I II III IV More than one of the above E 844 H HO HO H CHO OH H H OH CH2OH IV Chapter 22 Topic: Reactions 37. Which of the following substances will afford an optically inactive product upon reaction with nitric acid? HO HO H H CHO H H OH OH CH2OH H H H H I A) B) C) D) E) Ans: CHO OH OH OH OH CH2OH HO H H HO II CHO H OH OH H CH2OH H HO HO H III CHO OH H H OH CH2OH IV I II III and IV II, III and IV All of the above D Topic: Reactions 38. Which of the following substances will afford a meso- product upon reaction with Br2/H2O ? HO HO H H CHO H H OH OH CH2OH I A) B) C) D) E) Ans: H H H H CHO OH OH OH OH CH2OH II HO H H HO CHO H OH OH H CH2OH III I II III and IV II, III and IV None of the above E 845 H HO HO H CHO OH H H OH CH2OH IV Chapter 22 Topic: Reactions 39. Which of these reacts with dilute HCl to produce methanol? CH2OH O OH CH2OH O CH2OCH3 O OH OCH3 OH OH OH I HOH2C II O OCH3 CH2OH OH OH IV A) B) C) D) E) Ans: OH OH OH OCH3 H3COH2C OH OH III CH2OH O OH OH OH V I II III IV V D Topic: Reactions 40. Which monosaccharide is recovered from the hydrolysis of glycogen? A) D-Galactose B) D-Glucose C) D-Gulose D) Cellobiose E) Maltose Ans: B Topic: Reactions 41. Which monosaccharide is recovered from the hydrolysis of starch? A) D-Galactose B) D-Glucose C) D-Gulose D) Cellobiose E) Maltose Ans: B 846 Chapter 22 Topic: Reagents 42. Sucrose reacts with which of these reagents? A) C6H5NHNH2 B) Cu2+ C) Br2/H2O D) H3O+ E) Ag(NH3)2+ Ans: D Topic: Reagents 43. Which reagent would cause the following conversion to take place? OH OCH3 A) B) C) D) E) Ans: ? O HO HO OCH3 OH O H3CO H3CO OCH3 OCH3 Excess CH3OH and KOH Excess CH3OH and HCl Excess (CH3)2SO4 and OHExcess CH3I and H3O+ Excess (CH3CO)2O C Topic: Reagents 44. Select the reagent(s) needed to perform the following transformation. HO HO O HO HO ? O HO HO OH HO HO A) B) CH3I, KOH C) D) E) (CH3)2SO4, NaOH CH3OH, HCl O O O O OCH3 Ans: D 847 OCH3 Chapter 22 Topic: Reagents 45. Which reagent will distinguish between the members of the following pair? H HO H H CHO OH H OH OH CH2OH H HO H H I CH2OH OH H OH OH CH2OH II Ag(NH3)2+ AgNO3/C2H5OH Br2/CCl4 HCl Hot KMnO4 A A) B) C) D) E) Ans: Topic: Reagents 46. Which reagent will distinguish between the members of the following pair? H HO H H CHO OH H OH OH CH2OH I A) B) C) D) E) Ans: H HO H H CO2H OH H OH OH CH2OH II Ag(NH3)2+ AgNO3/C2H5OH Br2/CCl4 HCl Hot KMnO4 A 848 Chapter 22 Topic: Reagents 47. Which reagent will distinguish between the members of the following pair? H HO H H CHO OH H OH OH CH2OH H HO H H I A) B) C) D) E) Ans: CHO OCH3 H OCH3 OCH3 CH2OH II Ag(NH3)2+ AgNO3/C2H5OH Br2/CCl4 KMnO4 HIO4 E Topic: Reagents 48. Which of the following would give a positive test with Benedict's or Fehling's solution? OH OH O HO HO OH OCH3 O HO HO I OH OCH3 II OH HOH2C O HO HO OCH3 OH O HO CH2OH OCH3 OH III A) B) C) D) E) Ans: IV I II III IV All of these C 849 Chapter 22 Topic: Product Ratios 49. What is the ratio of products formed by the reaction of periodic acid with the following compound? H H H H CHO OH OH OH OH CH2OH I II III IV V A) B) C) D) E) Ans: H2C=O HCO2H CO2 5 3 1 1 0 1 3 5 4 4 0 0 0 1 2 I II III IV V C 850 Chapter 22 Topic: Product Ratios 50. What is the ratio of products formed by the reaction of periodic acid with the following compound? CH2OH C O H OH HO H H OH CH2OH H2C=O 5 3 1 2 0 I II III IV V A) B) C) D) E) Ans: HCO2H 1 3 5 3 4 CO2 0 0 0 1 2 I II III IV V D Topic: Product Ratios 51. Which of these is a component of the mixture formed when D-galactose is placed in aqueous base (de Bruyn - van Ekenstein transformation)? HO H H HO CHO H OH OH H CH2OH I A) B) C) D) E) Ans: H H HO H CHO OH OH H OH CH2OH II H HO H H CHO OH H OH OH CH2OH III I II III IV V E 851 HO HO H H CHO H H OH OH CH2OH IV CH2OH HO HO H C O H H OH CH2OH V Chapter 22 Topic: Named Reactions and Structure Identification 52. The Kiliani-Fisher Synthesis is the reaction of an aldose with: A) Br2/H2O; then HCN; then H3O+; then Na-Hg, H2O B) HCN; then Ba(OH)2; then H3O+; then Na-Hg, H2O C) HCN; then H3O+; then Ba(OH)2; then Na-Hg, H2O D) Br2/H2O; then H2O2, Fe2(SO4)3 E) Br2/H2O Ans: B Topic: Named Reactions and Structure Identification 53. The Ruff degradation is the reaction of an aldose with: A) Br2/H2O; then HCN; then H3O+; then Na-Hg, H2O B) HCN; then Ba(OH)2; then H3O+; then Na-Hg, H2O C) HCN; then H3O+; then Ba(OH)2; then Na-Hg, H2O D) Br2/H2O; then H2O2, Fe2(SO4)3 E) Br2/H2O Ans: D Topic: Named Reactions and Structure Identification 54. An aldopentose, X, is subjected to a Kiliani-Fischer synthesis to produce two aldohexoses, Y and Z. Both Y and Z, when oxidized with nitric acid, yield optically active aldaric acids. Which structure represents X? HO HO H CHO H H OH CH2OH I A) B) C) D) E) Ans: HO H H CHO H OH OH CH2OH II H H H CHO OH OH OH CH2OH III I II III IV V B 852 HO HO HO CHO H H H CH2OH IV H H HO CHO OH OH H CH2OH V Chapter 22 Topic: Named Reactions and Structure Identification 55. Compound X is a reducing sugar which, on hydrolysis, affords two molar equivalents of D-glucose. This hydrolysis is catalyzed by an enzyme specific for glucosides of this type: CH2OH O OH OH OR OH What is the identity of X? A) Sucrose B) Lactose C) Maltose D) Cellobiose E) None of these Ans: C Topic: Named Reactions and Structure Identification 56. A polysaccharide, Y, undergoes hydrolysis on catalysis by an enzyme which catalyzes the hydrolysis of cellobiose, but not maltose. Complete methylation and acid hydrolysis of the permethylated Y yields better than 95% of 2,4,6-tri-0-methyl-D-glucose. Which is a plausible structure for the repeating unit of Y? CH2OH O OR CH2OR OH OR O O OR OH OR OH OR OH OH II I CH2OH OR OH O OH OH IV OR OH III CH2OH O OR OH A) B) C) D) E) Ans: CH2OH OR OR V I II III IV V D 853 Chapter 22 Topic: Named Reactions and Structure Identification 57. If the methyl glycoside of an aldohexose is treated with HIO4, one molar equivalent of HCHO is formed but no HCOOH. What size ring is present in the glycoside? A) Three-membered B) Four-membered C) Five-membered D) Six-membered E) Seven-membered Ans: C Topic: Named Reactions and Structure Identification 58. The pyranose form of an aldohexose which can react 1:2 with acetone in the presence of acid is which of these? HO OH OH HO OH OH O OH OH O HO HO OH OH O I II OH HO HO III HO OH O O OH OH OH OH OH IV A) B) C) D) E) Ans: OH OH OH V I II III IV V C 854 Chapter 22 Topic: Named Reactions and Structure Identification 59. Sugars that would yield the same phenylosazone are: CH2OH C O HO H H OH H OH CH2OH H HO H H I A) B) C) D) E) Ans: CHO OH H OH OH CH2OH II HO HO H H CHO H H OH OH CH2OH III H HO H HO CHO OH H OH H CH2OH H H HO H IV CHO OH OH H OH CH2OH V I and II II and III I, II, and III III and IV I, II, and V C Topic: Named Reactions and Structure Identification 60. Which is not an intermediate monosaccharide in the Kiliani-Fischer synthesis of Dmannose from D-glyceraldehyde? A) D-Ribose B) D-Threose C) D-Arabinose D) D-Erythrose E) More than one of these Ans: E Topic: Stereochemical Considerations 61. Reaction of D-ribose with bromine water would yield an optically: A) active aldonic acid. B) inactive aldonic acid. C) active aldaric acid. D) inactive aldaric acid. E) active uronic acid. Ans: A Topic: Stereochemical Considerations 62. Reaction of D-ribose with HNO3 would yield an optically: A) active aldonic acid. B) inactive aldonic acid. C) active aldaric acid. D) inactive aldaric acid. E) inactive uronic acid. Ans: D 855 Chapter 22 Topic: Stereochemical Considerations 63. Which would undergo mutarotation in neutral aqueous solution? CH2OH CH2OH O O OH OH HO OH OH A) B) C) D) E) Ans: OH OH OH CH2OH O OH CH2OH O OCH3 OH OH OH OH OH OH III II I I II III IV More than one of these E IV Topic: Stereochemical Considerations 64. Which of the following structures represent enantiomers? H HO H H CHO OH H OH OH CH2OH I A) B) C) D) E) Ans: HO HO H H CHO H H OH OH CH2OH II H H H H CHO OH OH OH OH CH2OH III I and II II and III III and IV III and V IV and V D 856 H H HO H CHO OH OH H OH CH2OH IV HO HO HO HO CHO H H H H CH2OH V Chapter 22 Topic: Stereochemical Considerations 65. Which of the following structures represent epimers? H HO H H CHO OH H OH OH CH2OH HO HO H H I A) B) C) D) E) Ans: CHO H H OH OH CH2OH H H H H II CHO OH OH OH OH CH2OH H H HO H III CHO OH OH H OH CH2OH HO HO HO HO IV CHO H H H H CH2OH V I and II II and III III and IV III and V IV and V A Topic: Stereochemical Considerations 66. Refer to the following structures. Which D-aldohexose would react with NaBH4 to yield an optically inactive alditol? H HO H H CHO OH H OH OH CH2OH I A) B) C) D) E) Ans: HO HO H H CHO H H OH OH CH2OH II H H H H CHO OH OH OH OH CH2OH III I II III IV V C 857 H H HO H CHO OH OH H OH CH2OH IV HO HO HO HO CHO H H H H CH2OH V Chapter 22 Topic: Stereochemical Considerations 67. Refer to the following structures. Which aldohexose when subjected to Fischer's endgroup interchange would be converted to a compound identical with itself? H HO H H CHO OH H OH OH CH2OH HO HO H H I A) B) C) D) E) Ans: CHO H H OH OH CH2OH H H H H II CHO OH OH OH OH CH2OH H H HO H III CHO OH OH H OH CH2OH HO HO HO HO IV CHO H H H H CH2OH V I II III IV V B Topic: Stereochemical Considerations 68. Which is an L-monosaccharide that would yield an optically active aldaric acid on oxidation by nitric acid? CH2OH C O HO H H OH H OH CH2OH I A) B) C) D) E) Ans: H HO H H CHO OH H OH OH CH2OH II HO H H HO CHO H OH OH H CH2OH III I II III IV V D 858 H H HO HO CHO OH OH H H CH2OH IV HO HO HO HO CHO H H H H CH2OH V Chapter 22 Topic: Stereochemical Considerations 69. Which is the only one of these classes of carbohydrates which can include optically inactive members? A) Uronic acids B) Alditols C) Ketoses D) Glycosides E) Aldonic acids Ans: B Topic: Stereochemical Considerations 70. What are the correct designations for the stereogenic centers in this aldose: H HO HO CHO OH H H CH2OH A) B) C) D) E) Ans: 2R,3S,4R 2R,3S,4S 2S,3R,4R 2S,3S,4R 2R,3R,4S B 859 Chapter 22 Topic: Combination Problems 71. Consider the structures of D-allose below: H H H H CHO OH OH OH OH CH2OH D-Allose Which of the following structures represents L-allose? HO H H HO CHO H OH OH H CH2OH H H H HO I A) B) C) D) E) Ans: CHO OH OH OH H CH2OH HO H HO H II CHO H OH H OH CH2OH III HO HO HO HO CHO H H H H CH2OH IV H H HO HO CHO OH OH H H CH2OH V I II III IV V B Topic: Stereochemistry 72. Consider the structures below: what term(s) describe(s) the relationship between them? HO H H HO CHO H OH OH H CH2OH A) B) C) D) E) Ans: H H H HO CHO OH OH OH H CH2OH Enantiomers Epimers Diastereomers Anomers More than one of the above E 860 Chapter 22 Topic: Combination Problems 73. Consider the structures below. Which of the structures II-VI are epimers of I ? H H H H CHO OH OH OH OH CH2OH I HO H H HO CHO H OH OH H CH2OH II A) B) C) D) E) Ans: H H H HO CHO OH OH OH H CH2OH III HO H HO H CHO H OH H OH CH2OH IV HO HO HO HO CHO H H H H CH2OH V H H HO HO CHO OH OH H H CH2OH VI II III IV V VI B Topic: Combination Problems 74. Consider the structures below. An L-aldohexose, X, is treated with nitric acid to yield an optically inactive aldaric acid. The same L-aldohexose, X, is subjected to a Ruff degradation and the degradation product is oxidized with nitric acid to produce an optically inactive aldaric acid. Which is a possible structure for X? HO H H HO CHO H OH OH H CH2OH I A) I B) II C) III D) IV E) V Ans: D H H H HO CHO OH OH OH H CH2OH II HO H HO H CHO H OH H OH CH2OH III 861 HO HO HO HO CHO H H H H CH2OH IV H H HO HO CHO OH OH H H CH2OH V Chapter 22 Topic: Combination Problems 75. Consider the structures below. Which monosaccharides would yield an optically active aldonic acid when oxidized with bromine water? H H H H CHO OH OH OH OH CH2OH I A) B) C) D) E) Ans: HO H H HO CHO H OH OH H CH2OH H H H HO II I, II, and III I, II, and V III, IV, and VI II, III, and IV All of these E CHO OH OH OH H CH2OH HO H HO H III CHO H OH H OH CH2OH HO HO HO HO IV CHO H H H H CH2OH H H HO HO V CHO OH OH H H CH2OH VI Topic: Combination Problems 76. Consider the structures above. Which monosaccharides would yield the same phenylosazone when treated with excess phenylhydrazine? H H H H CHO OH OH OH OH CH2OH I A) B) C) D) E) Ans: HO H H HO CHO H OH OH H CH2OH II H H H HO CHO OH OH OH H CH2OH III HO H HO H CHO H OH H OH CH2OH IV I and V I and III II and III III and VI IV and V C 862 HO HO HO HO CHO H H H H CH2OH V H H HO HO CHO OH OH H H CH2OH VI Chapter 22 Topic: Combination Problems 77. Refer to the structures below. Which sugar(s) would yield an optically active aldaric acid on oxidation with nitric acid? H H H CHO OH OH OH CH2OH I A) B) C) D) E) Ans: HO H H CHO H OH OH CH2OH II I and III I, II, III, and V II III and IV I and V C H HO H CHO OH H OH CH2OH HO H HO III CHO H OH H CH2OH HO HO HO CHO H H H CH2OH IV V Topic: Combination Problems 78. Refer to the structures below. Which are L-sugars? CHO H OH H OH H OH CH2OH I A) B) C) D) E) Ans: CHO HO H H OH H OH CH2OH CHO H OH HO H H OH CH2OH CHO HO H H OH HO H CH2OH CHO HO H HO H HO H CH2OH II III IV V II and IV I, II, and III I and V III, IV, and V IV and V E 863 Chapter 22 Topic: Combination Problems 79. Refer to the structures below. Which sugars would react with phenylhydrazine to yield the same phenylosazone? H H H CHO OH OH OH CH2OH I A) B) C) D) E) Ans: HO H H CHO H OH OH CH2OH II H HO H CHO OH H OH CH2OH III HO H HO CHO H OH H CH2OH IV HO HO HO CHO H H H CH2OH V I and II III and IV I and V II and III III and V A Topic: General Information 80. The D-glucose unit at the branching point of amylopectin has free hydroxyl groups at which positions? A) C2, C3, and C6 B) C2 and C3 C) C3 and C4 D) C3, C4, and C6 E) C4 and C6 Ans: B Topic: General Information 81. Cellulose differs from chitin in which way? A) Cellulose has β-glycosidic linkages; chitin has ∝-glycosidic linkages. B) Cellulose contains only D-glucose units; chitin contains only N-acetyl-Dglucosamine units. C) Cellulose cannot be hydrolyzed; chitin can be hydrolyzed. D) Cellulose has a linear structure; chitin has a helical structure. E) Cellulose chains are branched; chitin chains are unbranched. Ans: B Topic: General Information 82. Cellulose lacks nutritive value for humans because: A) the products of its digestion are excreted without utilization. B) its conformation prevents attack by digestive enzymes. C) we lack the enzymes which can catalyze the hydrolysis of the glycosidic linkages. D) it passes through the digestive tract so rapidly. E) the molecules possess such a high molecular weight. Ans: C 864 Chapter 22 SHORT ANSWER QUESTIONS Topic: General Information 83 Sugars that give positive tests with Benedict's or Tollens' solution are called _______________. Ans: reducing sugars Topic: General Information 84. Bromine water is a reagent that converts an aldose to an ___________. Ans: aldonic acid Topic: General Information 85. The simplest carbohydrates (those that cannot be hydrolyzed to simpler carbohydrates) are called ______________. Ans: monosaccharides Topic: General Information 86. Carbohydrates that hydrolyze to give a large number of molecules of monosaccharides are called _____________. Ans: polysaccharides Topic: General Information 87. Carbohydrates are synthesized in green plants by _____________. Ans: photosynthesis Topic: General Information 88. A monosaccharide containing six carbon atoms and an aldehyde functionality is called an _____________. Ans: aldohexose Topic: General Information 89. Many carbohydrates exist in equilibrium with cyclic hemiacetals. Those carbohydrates that form a five-membered cyclic hemiacetal are called _____________. Ans: furanoses Topic: General Information 90. Ordinary table sugar is a disaccharide called __________. Ans: sucrose Topic: General Information 91. Milk contains a disaccharide called __________. Ans: lactose 865 Chapter 22 Topic: General Information 92. The method of lengthening the carbon chain of an aldose through the addition of HCN followed by hydrolysis and reduction is called the ______________. Ans: Kiliani-Fischer synthesis Topic: General Information 93. A polysaccharide found in the shells of lobsters, crabs, and in the exoskeletons of insects and spiders is called _________. Ans: chitin Topic: Aldaric Acids 94. Draw the structure(s) of the γ-lactone(s) that can be formed from D-Glucaric acid. CO2H H HO OH H H OH H OH CO2H D-glucaric acid Ans: CO2H H HO OH H O CO2H -H2O H OH O H H OH H OH H OH H OH CO2H C H and γ−lactones 866 OH HO H H O H OH CO2H O D-glucaric acid C Chapter 22 Topic: Aldaric Acids 95. Consider the structure of D-erythrose, shown below. Draw the structure of the product obtained upon treatment of D-erythrose with nitric acid. Give its IUPAC name and comment on its stereochemistry. O H H OH H OH CH2OH D-erythrose Ans: The product, 2,3-dihydroxybutanedioic acid, is expected to be optically inactive, due to a meso- configuration: (2R,3S) or (2S,3R). O H H OH H OH CH2OH D-erythrose CO2H HNO3 H OH H OH CO2H 2,3dihydroxybutanedioic acid (meso) Topic: Periodate Oxidations 96. What products are expected from the reaction of 3-hydroxy-2,4-pentanedione with 2 molar equivalents of periodic acid? O O O O Ans: 2 eq HIO4 2 + OH OH 867 H OH Chapter 22 Topic: Periodate Oxidations 97. Suggest a simple chemical test that you might use to distinguish between 2,3pentanediol and 2,4-pentanediol? Ans: Periodic acid test: 2,3- pentanediol is expected to undergo oxidative cleavage with periodic acid to afford acetic acid and propanoic acid. By contrast, no reaction is expected in an analogous treatment of 2,4-pentanediol, since the hydroxyl groups are separated by a methylene group. OH OH OH OH HIO4 OH + HIO4 O O no reaction OH Topic: Kiliani Fischer Synthesis 98. What products are expected to be formed upon subjecting L-erythrose (shown below) to the following reaction sequence? (Draw Fischer projection formulas) i) HCN; ii) Ba(OH)2; iii) H3O+; iv) Na(Hg), H2O, pH 3-5 Ans: Kiliani Fischer Synthesis: O O H H i) HCN O H HO H HO H CH2OH L-erythrose ii) Ba(OH)2 HO iii) H3O+ HO H HO H iv) Na(Hg), H2O, pH 3-5 868 H H CH2OH + OH HO H HO H CH2OH Chapter 22 Topic: Ruff Degradation 99. What products are expected to be formed upon subjecting D-galactose (shown below) to the following reaction sequence? (Draw Fischer projection formulas) i) Br2, H2O; ii) H2O2, Fe2(SO4)3 CHO H OH HO H HO H H OH CH2OH D-galactose Ans: Ruff degradation CHO H OH HO H HO H H OH CHO i. Br2, H2O ii. H2O2, Fe2(SO4)3 HO H HO H H OH CH2OH CH2OH D-galactose Topic: Epimers 100. Draw structures for 3 different epimers of D-glucose. CHO H HO OH H H OH H OH CH2OH D-Glucose CHO Ans: CHO CHO HO H H OH H HO H H OH HO H H OH H OH HO H H OH H OH H CH2OH CH2OH OH OH CH2OH 869 Chapter 23 MULTIPLE CHOICE QUESTIONS Topic: General Lipid Types and Information 1. Which of the following statements regarding lipids is not true? A) Lipids are soluble in non-polar organic solvents. B) All lipids have the same functional groups. C) Lipids include waxes, steroids, and triacylglycerols. D) Lipids have little in common except their solubility. E) Many lipids have biological roles. Ans: B Topic: General Lipid Types and Information 2. Which of the following statements regarding triacylglycerols is not true? A) They undergo alkaline hydrolysis to yield soaps. B) They are liquid if they have alkene bonds. C) They are solid if they do not have alkene bonds. D) Some can be hydrogenated. E) They are soluble in water. Ans: E Topic: General Lipid Types and Information 3. Which of the following statements regarding triacylglycerols is true? A) They form micelles when mixed with water. B) They are liquid if they are unsaturated. C) They are solid if they have alkyne bonds. D) They can be used to wash dirty dishes E) They are soluble in water. Ans: B Topic: General Lipid Types and Information 4. Which of the following statements regarding triacylglycerols is not true? A) They are synthesized in the body by adipocytes. B) They have an odd number of carbon atoms. C) They are solid if they do not have alkene bonds. D) Those which can be hydrogenated, undergo a significant change in melting point upon hydrogenation. E) They can be hydrolyzed to give glycerol and fatty acids. Ans: B 870 Chapter 23 Topic: General Lipid Types and Information 5. Which of the following statements regarding triacylglycerols is not true? A) Some undergo autooxidation with oxygen from air. B) They are solid if they do not have alkene bonds. C) They form lipid bilayers. D) They form micelles in water. E) Two of the above are false statements. Ans: E Topic: General Lipid Types and Information 6. Which of the following is a phosphatidic acid? CH2OOCR CH2OH CH2OPO3H2 CHOOCR' CHOOCR CHOH CH2OOCR" CH2OOCR' CH2OH I II III CH2OOCR CH2OPO3PO3H2 CHOOCR' CHOOCR CH2OPO3H2 CH2OOCR' IV A) B) C) D) E) Ans: V I II III IV V D Topic: General Lipid Types and Information 7. Which type of lipid gives these products on saponification: HOCH2CHOHCH2OH A) Fat B) Wax C) Lecithin D) Cephalin E) Plasmalogen Ans: D RCO2¯ R'CO2¯ 871 PO43¯ HOCH2CH2NH2 ? Chapter 23 Topic: General Lipid Types and Information 8. Which type of lipid gives the following products on saponification? HOCH2CHOHCH2OH A) Fat B) Wax C) Lecithin D) Cephalin E) Plasmalogen Ans: C RCO2¯ R'CO2¯ PO43¯ [HOCH2CH2N(CH3)3]+OH− Topic: General Lipid Types and Information 9. Which type of lipid gives these products on saponification: HOCH2CHOHCH2OH A) Fat B) Wax C) Lecithin D) Cephalin E) Plasmalogen Ans: E RCO2¯ RCH2CHO PO43¯ Topic: General Lipid Types and Information 10. Which of these lipids does not yield glycerol upon hydrolysis? A) A lecithin B) A sphingolipid C) A cephalin D) A triacylglycerol E) A plasmalogen Ans: B Topic: General Lipid Types and Information 11. Which of these lipids yields glycerol upon hydrolysis? A) A lecithin B) A phosphatidylserine C) A cephalin D) A triacylglycerol E) All of the above Ans: E 872 HOCH2CH2NH2 ? Chapter 23 Topic: General Lipid Types and Information 12. Which of these lipids yields choline upon hydrolysis? A) A lecithin B) A sphingomyelin C) A cephalin D) A cerebroside E) Two of the above Ans: E Topic: General Lipid Types and Information 13. Choline cannot be found as a product of hydrolysis of any representative of this class of lipids. A) Sphingomyelins B) Lecithins C) Plasmalogens D) Waxes E) Both C) and D) Ans: D Topic: General Lipid Types and Information 14. Choline cannot be found as a product of hydrolysis of any representative of this class of lipids. A) Cerebrosides B) Phosphatidylserine C) Plasmalogens D) Waxes E) None of the above yield choline upon hydrolysis Ans: E Topic: General Lipid Types and Information 15. D-galactose is an example of a class of compounds that can be formed during the hydrolysis of A) Sphingomyelins B) Cerebrosides C) Plasmalogens D) Waxes E) Both C) and D) Ans: B 873 Chapter 23 Topic: General Lipid Types and Information 16. Which of these is a wax? H A) CH3(CH2)20C=O O B) CH3(CH2)24COCH2(CH2)28CH3 H H C) O CH3(CH2)7C=C(CH2)7COCH2CH3 D) CH2OOC(CH2)16CH3 CHOOC(CH2)14CH3 CH2OOC(CH2)14CH3 E) CH3(CH2)24CH2OH Ans: B Topic: General Lipid Types and Information 17. Which of these is most likely to have properties resembling natural waxes? O I O II O O III O O O IV O O V A) B) C) D) E) Ans: N H O I II III IV V D 874 O Chapter 23 Topic: General Lipid Types and Information 18. OCH2CH2N(CH3)3 is a structural unit of which type of phosphatide? A) Cephalins B) Phosphatidyl serines C) Plasmalogens D) Lecithins E) Both C) and D) Ans: E Topic: General Lipid Types and Information 19. OCH2CH2NH2 is a structural unit of which type of phosphatide? A) Cephalins B) Phosphatidyl serines C) Plasmalogens D) Lecithins E) Both A) and C) Ans: E Topic: Fats and Oils 20. Which of the following would serve as the basis for a simple chemical test that would distinguish between stearic acid and oleic acid? A) NaOH/H2O B) NaHCO3/H2O C) HCl/H2O D) Ag(NH3)2+ E) Br2/CCl4 Ans: E Topic: Fats and Oils 21. Which of the following would not be helpful in distinguishing between oleic acid, linoleic acid and linolenic acid? A) Examine the stoichiometry of the reaction with Br2, CCl4 B) Examine the stoichiometry of complete catalytic hydrogenation. C) Examine products obtained after subjecting the sample to catalytic hydrogenation D) Examine products obtained after subjecting the sample to : i) O3, CH2Cl2; ii) Zn, CH3CO2H E) All of the above would be helpful. Ans: C 875 Chapter 23 Topic: Fats and Oils 22. Which of the following might be helpful in distinguishing between oleic acid and linoleic acid? A) Examine the stoichiometry of the reaction with NaOH/H2O B) Examine the stoichiometry of complete catalytic hydrogenation. C) Examine products obtained after subjecting the sample to catalytic hydrogenation D) Examine products obtained after subjecting the sample to : i) O3, CH2Cl2; ii) Zn, CH3CO2H E) Two of the above Ans: E Topic: Fats and Oils 23. Which fatty acid is not likely to occur commonly in natural sources? A) CH3(CH2)12COOH B) CH3(CH2)14COOH C) CH3(CH2)5 (CH2)7CO2H H D) CH3(CH2)4 CH2 H E) H H H (CH2)7CO2H H CH3(CH2)12CHCH2CO2H CH3 Ans: E 24. Which fatty acid is not likely to occur commonly in natural sources? A) Tetradecanoic acid B) Pentadecanoic acid C) Hexadecanoic acid D) (9Z,12Z)-octadeca-9,12-dienoic acid E) (Z)-hexadeca-9-enoic acid Ans: B 876 Chapter 23 25. Which fatty acid is not likely to occur commonly in natural sources? A) (Z)- 11-Tetradecenoic acid B) (Z)- 9-Pentadecenoic acid C) Hexadecanoic acid D) (9Z,12Z)- 9,12-octadecadienoic acid E) (Z)-9-hexadecenoic acid Ans: B 26. Which fatty acid is likely to occur commonly in natural sources? OH I O O II OH OH III O OH IV O O V A) B) C) D) E) Ans: OH II I and IV II and III II, III and IV V E Topic: Fats and Oils 27. Which of the following could be used to prepare myristic acid, CH3(CH2)12COOH? A) CH3(CH2)11CH2Br, CN-, heat; then H3O+, heat B) CH3(CH2)11CH2Br, Mg, (C2H5)2O; then CO2; then H3O+ C) CH3(CH2)12CHO, Ag2O, OH-; then H3O+ D) Answers A) and B) E) Answers A), B), and C) Ans: E 877 Chapter 23 Topic: Fats and Oils 28. Which of the following could be used to prepare myristic acid, CH3(CH2)12COOH? A) CH3(CH2)11CH2Br, CN-, heat; then H3O+, heat B) CH3(CH2)11CH2Br, Mg, (C2H5)2O; then CO2; then H3O+ C) CH3(CH2)13CHO, Ag2O, OH-; then H3O+ D) Answers A) and B) E) Answers A), B), and C) Ans: D Topic: Fats and Oils 29. Which of the following could be used to prepare stearic acid, CH3(CH2)16COOH? A) CH3(CH2)15CH2Br, CN-, heat; then H3O+, heat B) CH3(CH2)15CH2Br, Mg, (C2H5)2O; then HCHO; then H3O+ C) CH3(CH2)16CH2Br, NaOH; then KMnO4,OH-, H2O; then H3O+ D) Answers A) and B) E) Answers A) and C) Ans: E Topic: Fats and Oils 30. How could you synthesize stearolic acid, CH3(CH2)7C≡C(CH2)7COOH from oleic acid, CH3(CH2)7CH=CH(CH2)7COOH? A) Br2, CCl4; then 3 NaNH2, heat; then H3O+ B) Li, liq. NH3; then H3O+ C) H2, Pd D) Peracid; then H3O+; then HA, H2O, heat E) excess HCl; then KOH, C2H5OH, heat Ans: A Topic: Fats and Oils 31. Which of these reagents would not react with oleic acid? A) H2, Ni B) PBr3 C) CH3MgI D) NH3/H2O E) NaBH4 Ans: E 878 Chapter 23 Topic: Fats and Oils 32. Which of these reagents would not react with oleic acid? A) H2, Ni B) DIBAL-H C) O3/CH2Cl2 D) NH3/H2O E) LAH Ans: B Topic: Fats and Oils 33. Which of these reagents would not react with stearic acid? A) H2, Ni B) SOCl2 C) CH3MgI D) NH3/H2O E) LAH Ans: A Topic: Fats and Oils 34. What would be the product, X, of the following reaction sequence? i. SOCl2 X CH3(CH2)12COOH ii. NH3 iii. Br2, NaOH CH3(CH2)12CHCOOH A) Br B) CH3(CH2)11CHCONH2 Br C) CH3(CH2)11CH2NH2 D) CH3(CH2)12CONH2 E) CH3(CH2)12COBr Ans: C 879 Chapter 23 Topic: Fats and Oils 35. The final product of the following reaction sequence would be:, OH O i. PBr3 ii. LiAlH[OC(CH3)3] iii. NaCN, HCl + iv. H3O , heat ? OH O OH O I II O O OH III IV O OH V A) B) C) D) E) Ans: I II III IV V D Topic: Fats and Oils 36. What would be the product of the following reaction sequence? i. H2, Ni ? ii. SOCl2 iii. CH3(CH2)14CH2OH, HA A) CH3(CH2)5CH=CH(CH2)14CH3 B) CH3(CH2)5COOCH2(CH2)14CH3 CH3(CH2)5CH=CH(CH2)7COOCH2(CH2)14CH3 C) CH3(CH2)14COOCH2(CH2)14CH3 D) CH3(CH2)13CHClCOOCH2(CH2)14CH3 E) CH3(CH2)5CH=CH(CH2)7COOCH2(CH2)14CH3 Ans: C CH3(CH2)5CH=CH(CH2)7CO2H 880 Chapter 23 Topic: Fats and Oils 37. The product of the following reaction sequence may be described as? i. H2, Ni CH3(CH2)5CH=CH(CH2)7CO2H ? ii. SOCl2 iii. CH3(CH2)14CH2OH, HA A) Alkoxyalkane B) Alkyl alkanoate C) Alkyl alkenoate D) Acyl glycerol E) Acyl Alkane Ans: B 881 Chapter 23 Topic: Fats and Oils 38. The product of the following reaction sequence is nervonic acid. What is the structure of nervonic acid? HC CNa NaNH2 C10H17Na C10H18 1-bromooctane NH3(l) ICH2(CH2)11CH2Cl C24H43O2K KOH heat C24H43N NaCN C23H43Cl H3O+ H2, P-2 C24H44O2 A) CH3(CH2)7 H B) CH3(CH2)7 H C) CH3(CH2)9 H D) E) CH3(CH2)13 H (CH2)13CO2H (CH2)13CO2H H (CH2)11CO2H H H H (CH2)7CO2H CH3(CH2)13 (CH2)7CO2H H C24H46O2 nervonic acid H Ans: B 882 Chapter 23 Topic: Fats and Oils 39. Which fatty acid is responsible for the putrid odor of rancid butter? A) Valeric acid B) Myristic acid C) Stearic acid D) Oleic acid E) Butyric acid Ans: E Topic: Fats and Oils 40. How could you convert an unsaturated fatty acid into a saturated fatty acid? A) KMnO4, OH-, heat B) OH-, H2O, heat; then H3O+ C) H2, Ni, pressure D) H3O+, H2O, heat E) O3; then Zn, HOAc Ans: C Topic: Fats and Oils 41. Which is an untrue statement concerning the fatty acid moieties of naturally-occurring triacylglycerols? A) Generally, they possess an even number of carbon atoms. B) Most have unbranched carbon chains. C) The double bonds, when present, all are in the cis configuration. D) Where two or three double bonds are present in the same fatty acid moiety, they comprise a conjugated system. E) The fatty acid moieties in a particular triacylglycerol usually are different. Ans: D Topic: Fats and Oils 42. Which is not a correct statement concerning naturally-occurring triacylglycerols? A) The greater the degree of unsaturation, the higher the melting point. B) Saponification yields glycerol and a mixture of carboxylic acid salts. C) Solid examples are termed "fats." D) Regardless of the exact nature of the R groups, such compounds are waterinsoluble. E) Such compounds frequently, but less correctly, are called "triglycerides." Ans: A 883 Chapter 23 Topic: Fats and Oils 43. Of the saturated fatty acids found in fats and oils, this one normally is the most abundant: A) Capric acid B) Lauric acid C) Myristic acid D) Palmitic acid E) Stearic acid Ans: D Topic: Fats and Oils 44. The biosynthesis of one series of prostaglandins begins with which of these fatty acids? A) Palmitic acid B) Stearic acid C) Oleic acid D) Linoleic acid E) Arachidonic acid Ans: E Topic: Fats and Oils 45. The ozonolysis of a fatty acid produces these fragments: O O OH O O O What is the identity of the fatty acid? A) Stearic acid B) Palmitoleic acid C) Oleic acid D) Linoleic acid E) Linolenic acid Ans: D Topic: Fats and Oils 46. How many isomers, including stereoisomers, exist for the triacylglycerol which, on saponification, gives 2 molar equivalents of palmitate and 1 molar equivalent of stearate? A) 1 B) 2 C) 3 D) 4 E) 6 Ans: C 884 Chapter 23 Topic: Soaps, Detergents, and Micelles 47. Consider a micelle composed of phosphatidyl choline, shown below. Which part(s) of the molecule would form the hydrophilic surface of the micelle? CH2OOC15H31 1 CHOOC17H35 2 CH2O O A) B) C) D) E) Ans: OCH2CH2N(CH3)3 P 3 O 3 2 1 1 and 2 2 and 3 A Topic: Soaps, Detergents, and Micelles 48. Which of these is a detergent? A) CH3(CH2)16COO-Na+ B) [CH3(CH2)14COO-]2Ca+2 C) CH3(CH2)10CH2SO3-Na+ D) HOCH2CHOHCH2OH E) CH3(CH2)14CH2SH Ans: C Topic: Terpenes 49. Which compound is a sesquiterpene? OH I III A) B) C) D) E) Ans: II IV V I II III IV V D 885 Chapter 23 Topic: Terpenes 50. Which structure represents a terpene likely to be found in nature? O OH II I III A) B) C) D) E) Ans: IV V I II III IV V C Topic: Terpenes 51. To which class of terpenes does the terpene shown below, bisabolene, belong? A) B) C) D) E) Ans: Monoterpenes Sesquiterpenes Diterpenes Triterpenes Tetraterpenes B Topic: Terpenes 52. How many isoprene units are in vitamin A? OH A) B) C) D) E) Ans: 1 2 3 4 More than 4 D 886 Chapter 23 Topic: Terpenes 53. In β-carotene, how many tail-to-tail links of isoprene units are there? A) B) C) D) E) Ans: 1 2 3 4 More than 4 A Topic: Terpenes 54. Which compound below does not obey the isoprene rule? OH OH I II HO OH III A) B) C) D) E) Ans: IV V I II III IV V D 887 Chapter 23 Topic: Terpenes 55. Which of the following compounds would be most likely to be found in nature? (Hint: recall the isoprene rule.) OH OH I II OH OH III IV OH V A) B) C) D) E) Ans: I II III IV V D Topic: Rubber 56. Which is the proper representation of three successive isoprene units in natural rubber? H H H H H H I H II H H H H H IV III H H H V A) B) C) D) E) Ans: I II III IV V B 888 Chapter 23 Topic: Rubber 57. In the vulcanization of rubber, A) natural rubber is heated with sulfur. B) reaction occurs at allylic positions. C) cross-linking results in a hardening of the rubber. D) disulfide bridges are formed. E) All of the above Ans: E Topic: Rubber 58. Which is the repeating unit of natural rubber? I A) B) C) D) E) Ans: II III IV V I II III IV V A Topic: Steroids 59. What product would be obtained by catalytic hydrogenation of 5-cholesten-3β-ol? A) 5β-Cholestan-3β-ol B) 5∝-Cholestan-3β-ol C) 5∝-Cholestan-3∝-ol D) 5β-Cholestan-3∝-ol E) 5-Cholesten-3β,6∝-diol Ans: B Topic: Steroids 60. Which reagent might be used to convert 5∝-cholest-1-en-3-ol into 5∝-cholestan-3-ol? A) CrO3/pyridine B) KMnO4/H2O C) CH3MgI D) H2/Pt E) Li/C2H5NH2 Ans: D 889 Chapter 23 Topic: Steroids 61. Which reagent might serve as the basis for a simple chemical test that would distinguish between 5∝-cholest-1-en-3-one and 5∝-cholestan-3-one? A) Ag(NH3)2+ B) CrO3/H2SO4 C) Br2/CCl4 D) NaOH/H2O E) C6H5NHNH2 Ans: C Topic: Steroids 62. The synthesis of cortisone required placing a ketone function at the 11-position of a steroid. Where is position 11? III IV II V I A) B) C) D) E) Ans: I II III IV V C Topic: Steroids 63. How many stereogenic centers are there in cholesterol? HO A) B) C) D) E) Ans: 2 4 6 8 16 D 890 Chapter 23 Topic: Steroids 64. Which is an untrue statement concerning cholesterol? A) Cholesterol decolorizes a solution of Br2 in CCl4. B) Cholesterol reacts with 2,4-dinitrophenylhydrazine. C) Cholesterol is optically active. D) Cholesterol is water-insoluble. E) All of the above are true. Ans: B Topic: Steroids 65. The reaction of cholesterol with dilute aqueous KMnO4 at 0–5°C produces which of these compounds (A and B rings only shown)? HO HO OH HO OH I II HO HO OH IV A) B) C) D) E) Ans: HO HO III O HO V I II III IV V D 891 O OH Chapter 23 Topic: Steroids 66. In the biosynthesis of vitamin D2, which alkane bond of ergosterol is cleaved? II I IV III HO V A) B) C) D) E) Ans: I II III IV V D Topic: Steroids 67. Which of the following is a female sex hormone? A) Ergosterol B) Estradiol C) Cortisone D) Androsterone E) Cholic acid Ans: B Topic: Steroids 68. Which of these is a correct systematic name for progesterone? O O Progesterone A) 2-Estrene-4,20-dione B) 5-Androstene-4,19-dione C) 4-Pregnene-3,20-dione D) 5-Cholestene-5,19-dione E) 4-Cholene-3,20-dione Ans: C 892 Chapter 23 Topic: Steroids 69. Shown below is the formula for the antiinflammatory drug called prednisone. What is a correct systematic name for prednisone? O O OH OH O A) B) C) D) E) Ans: Prednisone 17∝,21-Dihydroxypregna-1,4-diene-3,11,20-trione 17β,21-Dihydroxypregna-1,4-diene-3,11,20-trione 17∝,19-Dihydroxypregna-1,4-diene-3,11,20-trione 17β,19-Dihydroxypregna-1,4-diene-3,11,20-trione None of the above A Topic: Steroids 70. What product would you expect when progesterone is treated with one molar equivalent of hydrogen in the presence of a platinum catalyst? O O A) B) C) D) E) Ans: Progesterone 5∝-Pregnane-3,20-dione 5β-Pregnane-3,20-dione 5∝-Estrane-3,20-dione 5β-Estrane-3,20-dione 5∝-Androstane-3,20-dione A 893 Chapter 23 Topic: Steroids 71. Which is the correct systematic name for the steroid shown below? CH3 H H3C H H HO H A) B) C) D) E) Ans: 5∝-Androstan-3∝-ol 5β-Androstan-3β-ol 5β-Androstan-3∝-ol 5∝-Androstan-3β-ol 5β-Estan-3β-ol D Topic: Steroids 72. Which of these is a male sex hormone? A) Estrone B) Testosterone C) Cholic acid D) Cortisone E) Estradiol Ans: B Topic: Prostaglandins 73. Which of the following characteristics are found in the class of C20 carboxylic acids called prostaglandins? A) a five membered ring B) One or more double bonds C) Several oxygen containing groups D) Two of the above E) All of the above Ans: E SHORT ANSWER QUESTIONS Topic: Lipids 74. Unlike carbohydrates and proteins, which are defined in terms of their structures, lipids are defined in terms of _____________. Ans: the physical operation used to isolate them 894 Chapter 23 Topic: Fats and Oils 75. Saturated fatty acids pack efficiently. Therefore the corresponding triacylglycerols tend to be __________ at room temperature and are called __________. Ans: solid; fats Topic: Fats and Oils 76. Unsaturated fatty acids have a bend in the carbon chain that interferes with packing. Therefore the corresponding triacylglycerols are generally __________ at room temperature and are called _______. Ans: liquid; oils Topic: Fats and Oils 77. The primary function of triacylglycerols (triglycerides) in animals is _____________. Ans: energy storage Topic: Fats and Oils 78. Salts of long-chain fatty acids are known as ___________. Ans: soaps Topic: Terpenes 79. Terpenes are built up from two or more five-carbon units known as __________. Ans: isoprene units Topic: Terpenes 80. When natural rubber is heated with sulfur, a reaction takes place that produces _____________ between the polymer chains. This process is known as _____________. Ans: cross-links; vulcanization Topic: Steroid Hormones 81. There are three major classes of sex hormones: a. female sex hormones [or ____________] b. male sex hormones [or ____________] c. pregnancy hormones [or ______________] Ans: a. estrogens; b. androgens; c. progestins Topic: Fats and Oils 82. Sphingolipids, proteins, and polysaccharides make up ___________, the protective coating around nerve fibers. Ans: myelin Topic: Fats and Oils 83. Explain how soap removes dirt from clothes. Ans: The hydrophobic end dissolves in the dirt and oil, forming a micelle with an ionic outer layer. The outer layer is hydrophilic and makes it easy for the micelle to wash away, carrying the dirt with it. 895 Chapter 23 Topic: Fats and Oils 84. Myelin, the protective coating around nerve fibers, is made up of ___________. Ans: sphingolipids, proteins, and polysaccharides Topic: Fats and Oils 85. The characteristic odor of rancid butter is attributed to ___________. Ans: the release of butyric acid during decomposition. Topic: Fats and Oils 86. In naturally occurring polyunsaturated fatty acids, the relative position of double bonds is rarely ___________. Ans: conjugated Topic: Fats and Oils 87. There is growing evidence that “trans” fats are associated with an increased risk of ___________, and the FDA now requires “trans fat” information to be provided on nutrition labels. Ans: cardiovascular disease Topic: Fats and Oils 88. In naturally occurring polyunsaturated fatty acids, the stereochemistry of the double bonds is rarely ___________. Ans: trans- Topic: Fats and Oils 89. Prolonged heating of naturally occurring polyunsaturated fats may cause the stereochemistry of the double bonds to change from ___________. Ans: cis- to trans- Topic: Fats and Oils 90. Most waxes, commonly found as protective coatings on skin, fur, hair, leaves, fruits, etc., are ____________. Ans: Esters of long chain fatty acids and long chain alcohols. 896 Chapter 23 Topic: Fats and Oils 91. Olestra, a synthetic fat substitute, contributes nothing to the caloric value of foods prepared with it, because it passes through the body without being digested. Why are the lipases, responsible for facilitating normal fat hydrolysis, unable to facilitate the hydrolysis of olestra? Ans: In order for a lipase to catalyze hydrolysis, the fat molecule must be accepted into the active site of the enzyme. Although olestra contains 6-8 ester groups, the molecule is extremely bulky: this steric bulk prevents lipases from accepting the molecule into their active sites. Consequently, the olestra is not hydrolyzed, hence not absorbed, so that it adds nothing to the caloric value of foods prepared with it. Topic: Fats and Oils 92. How could you synthesize stearolic acid, CH3(CH2)7C≡C(CH2)7COOH from oleic acid, CH3(CH2)7CH=CH(CH2)7COOH? Specify stoichiometric details, providing a brief explanation of your rationale. Ans: Topic: Fats and Oils 93. How are soaps and phosphatides similar in their interaction with water? Ans: Both have polar and non-polar groups, so that they appear to “dissolve” when mixed with water. In actuality, they tend to form spherical micelles: the molecules aggregate in such a way that the polar groups of all the molecules in the micelle face the water, while the non-polar groups face inward, toward the center of the micelle, thus maximizing both hydrophilic as well as hydrophobic interactions. Topic: Fats and Oils 94. Suggest a reasonable synthetic strategy for the synthesis of N,N-dimethylstearamide , CH3(CH2)16CON(CH3)2 from oleic acid, cis 9-octadecenoic acid Ans: i) H2,Ni; ii) PBr3; iii) (CH3)2NH H2 CH3(CH2)16CO2H CH3(CH2)7CH=CH(CH2)7CO2H Ni PBr3 CH3(CH2)16CON(CH3)2 (CH3)2NH 897 CH3(CH2)16COBr Chapter 23 Topic: Synthesis 95. One of the intermediates in a prostaglandin synthesis is shown below. NO2 CN O O CHO Which reaction might be employed to make this molecule from 1,1-dimethoxy-3nitropropane and an appropriate α,β-unsaturated aldehyde? Show the structural details of the reagents as well as any catalysts that might be needed. Ans: Deprotonation (with base) of the active hydrogen alpha to the –NO2 group would afford a nucleophilic species. Conjugate addition (Michael reaction) of this species to either isomer (cis/trans) of the α,β-unsaturated aldehyde drawn below should afford the desired compound in acceptable yields. CN NO2 NO2 O CN base + O or O O O CN 898 O CHO Chapter 23 Topic: Soaps and Synthetic Detergents 96. Draw the structures of the following substances, in which the alkyl portion is CH3(CH2)12−: sodium carboxylate, sodium alkanesulfonate and sodium alkyl sulfate Explain why these substances may be useful as “dirt removers”. Ans: − O Na sodium carboxylate + O O − sodium alkanesulfonate S O Na + O O − sodium alkyl sulfate O + S O Na O Each of these substances has a polar “head” and a non-polar “tail”. This allows them to form micelles when mixed with water. These micelle clusters are dispersed throughout the aqueous phase, with the polar heads on the outside and the non-polar ends on the inside of the spherical clusters. When these micelles come into contact with the non-polar, oily surface of “dirt”, the dirt gets attracted to the non-polar center of the micelle, where it is then “trapped”. Upon rinsing, the micelles, along with the trapped dirt, get washed away. Topic: Terpenes 97. What products would be obtained from the ozonolysis of zingiberine, found in the oil of ginger? i) O3 ii) Zn, CH3CO2H Zingiberine Ans: ? O O O O + + O O 899 Chapter 23 Topic: Terpenes 98. Identify the bonds that link the isoprene units in α-farnesene, shown below. How are these units linked: head to head, tail to head or tail to tail ? α-farnesene Ans: head tail head tail head tail α-farnesene 900 Chapter 23 Topic: Analysis and Structure Elucidation 99. A compound “Z” (C10H16), has λmax at 184 nm in its UV spectrum. Catalytic hydrogenation of Z affords a mixture of diasteromers, which upon separation are identified to be cis-1-isopropyl-4-methylcyclohexane and trans-1-isopropyl-4methylcyclohexane. Upon ozonolysis, Z yields formaldehyde and 3-acetyl-6oxoheptanal. Suggest a structure for Z that is consistent with all of the above data, clearly explaining your rationale. Ans: * excess H2, Ni λmax=184 nm cis- and trans- O ozonolysis O H2C=O + * O - IHD for Z: (C10H22 - C10H16)/2 = 3 - Hydrogenation affords 1-isopropyl-4-methylcyclohexane: so, Z must have the same carbon skeleton, along with 2 pi bonds, i.e., 1 ring and 2 pi bonds (so that IHD =3) - Examination of the above carbon skeleton suggests that the pi bonds cannot constitute an alkyne, so that the pi bonds must be present as 2 double bonds. - λmax at 184 nm in its UV spectrum suggests that these pi bonds are not conjugated. - The stereochemistry of the hydrogenation products suggests that there must be a pi bond at C-4 and a chiral center at C-1: hydrogenation eliminates the asymmetry (and therefore chirality) at C-4. Hydrogenation from both faces of the pi bond at C-4 would lead to cis- and trans- orientation of the methyl and isopropyl groups on the cyclohexane ring. - The ozonolysis products suggest the position of the 2 double bonds: since there are only 2 products, one bond must be within the ring, the other outside the ring. 901 Chapter 24 MULTIPLE CHOICE QUESTIONS Topic: Isoelectric Points and pH 1. Which amino acid would have its isoelectric point near pH 10? CH2COO H3NCH2CH2CH2CH2CHCOO NH3 H3NCHCOO NH3 NH2 I II HO III HOOCCH2CH2CHCOO CH2CHCOO NH3 NH3 IV A) B) C) D) E) Ans: V I II III IV V B Topic: Isoelectric Points and pH 2. Which amino acid would have its isoelectric point near pH 3? H3CCHCOO CH2CHCOO NH3 NH3 I HOOCCH2CH2CHCOO NH3 II III NH2 H3NCH2CH2CH2CH2CHCOO H2NCCH2CH2CH2CHCOO NH2 NH2 IV A) B) C) D) E) Ans: V I II III IV V C 902 Chapter 24 Topic: Isoelectric Points and pH 3. Which amino acid would have its isoelectric point near pH 10? CO2 CO2 CO2 H2N H3N H H H CH2CH2CH2NH3 CH2CH2CO2H I II CO2 H CH2OH IV A) B) C) D) E) Ans: CH2SH III CO2 H3N NH3 H3N H CH2C6H5 V I II III IV V A Topic: Isoelectric Points and pH 4. Which amino acid would have its isoelectric point near pH 10? A) Glycine B) Tryptophan C) Serine D) Proline E) Lysine Ans: E Topic: Isoelectric Points and pH 5. Which amino acid would not have its isoelectric point in the pH range 5-7? A) Leucine B) Threonine C) Methionine D) Arginine E) Cystine Ans: D 903 Chapter 24 Topic: Isoelectric Points and pH 6. Which amino acid would not have its isoelectric point in the pH range 5-7? A) Glycine B) Proline C) Cysteine D) Glutamine E) All of these amino acids have isoelectric point in the pH range 5-7 Ans: E Topic: Isoelectric Points and pH 7. What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 10? A) It must have a hydrophobic side chain B) It must have a hydrophilic side chain C) Its side chain must contain a basic group D) Its side chain must contain an acidic group E) None of the above is a valid conclusion Ans: C Topic: Isoelectric Points and pH 8. What might be concluded upon determining that an unknown amino acid has its isoelectric point near pH 3? A) It must have a hydrophobic side chain B) It must have a hydrophilic side chain C) Its side chain must contain a basic group D) Its side chain must contain an acidic group E) None of the above is a valid conclusion Ans: D Topic: Isoelectric Points and pH 9. The pH at which the concentration of the dipolar ion (zwitterion) form of an amino acid is at a maximum and the cationic and anionic forms are at equal concentrations is termed the A) end point. B) equivalence point. C) neutral point. D) isoelectric point. E) dipolar point. Ans: D 904 Chapter 24 Topic: Isoelectric Points and pH 10. What is the pI of the following amino acid? HO2C (CH2)n CO2H NH2 pKa1= 2.4 pKa2= 10.0 α-CO2H A) 1.6 B) 3.2 C) 5.5 D) 6.2 E) 7.0 Ans: B α-NH3+ pKa3= 4.0 R group Topic: Isoelectric Points and pH 11 What is the pI of the following amino acid? HO2C (CH2)n CO2H NH2 pKa1= 2.2 pKa2= 9.7 α-CO2H α-NH3+ A) B) C) D) E) Ans: pKa3= 4.3 R group 2.1 3.2 5.9 6.5 7.0 B 905 Chapter 24 Topic: Isoelectric Points and pH 12. What is the pI of the following amino acid? HO2C (CH2)n NH2 NH2 pKa1= 2.2 pKa2= 9.0 + α-NH3 α-CO2H A) 1.5 B) 6.3 C) 5.6 D) 9.8 E) 6.8 Ans: D pKa3= 10.5 R group Topic: Isoelectric Points and pH 13. What is the pI of the following amino acid? HO2C (CH2)n CH3 NH2 pKa1= 2.4 pKa2= 9.6 α-CO2H A) 12 B) 3.6 C) 4.8 D) 6.0 E) 7.2 Ans: D α-NH3 + 906 Chapter 24 Topic: Isoelectric Points and pH 14. Consider the following tripeptide: H2N-leu-lys-phe-CO2H NH2 What is the best estimate of the pI of this compound? pKa leu lys phe A) B) C) D) E) Ans: pKa COOH 2.4 2.2 1.8 6.2 7.1 9.2 10.1 11.3 D pKa NH3+ 9.6 9.0 9.1 pI R 6.0 9.8 5.5 10.5 Topic: Isoelectric Points and pH 15. What would be the predominant form of lysine in water at pH 14? H3N CO2H H3N CO2 H3N NH3 NH3 I NH2 II H2N CO2 III H2N CO2 NH3 NH2 IV A) B) C) D) E) Ans: CO2 V I II III IV V E 907 Chapter 24 Topic: Isoelectric Points and pH 16. The predominant form of aspartic acid in water at pH 1 would be: CO2H HO2C CO2H O2 C NH3 NH3 NH3 I II CO2H O2C III CO2 O2C NH2 NH2 IV A) B) C) D) E) Ans: CO2 HO2C V I II III IV V A Topic: Isoelectric Points and pH 17. For the accompanying fully-protonated amino acid, what is the arrangement of pKa values in order of increasing magnitude? HO2C I CO2H NH3 III II A) I < II < III B) II < I < III C) III < I < II D) III < II < I E) II < III < I Ans: C Topic: Amino Acid Structure 18. Which of these amino acids contains a hydrophobic side chain? A) Lysine B) Serine C) Methionine D) Arginine E) Cysteine Ans: C 908 Chapter 24 Topic: Amino Acid Structure 19. Which of these natural amino acids contains an amide function? A) Asparagine B) Proline C) Arginine D) Histidine E) None of these Ans: A Topic: Amino Acid Structure 20. Which of these natural amino acids contains a heterocyclic ring? A) Asparagine B) Proline C) Arginine D) Histidine E) Two of these Ans: E Topic: Amino Acid Structure 21. Which of these natural amino acids contains an amide function? A) Asparagine B) Methionine C) Cysteine D) Glutamine E) Two of these Ans: E Topic: Amino Acid Structure 22. Which of these natural amino acids contains two carboxylic acid groups? A) Cystine B) Cysteine C) Glutamic acid D) A and B E) A and C Ans: A 909 Chapter 24 Topic: Amino Acid Structure 23. Which of these natural amino acids contains a phenolic group? A) Phenylalanine B) Tyrosine C) Tryptophan D) 4-Hydroxyproline E) Serine Ans: B Topic: Amino Acid Structure 24. Which of these natural amino acids contains a pyrrolidine ring? A) Phenylalanine B) Tyrosine C) Tryptophan D) 4-Hydroxyproline E) Serine Ans: D Topic: Amino Acid Structure 25. Which of these natural amino acids contains an indole ring? A) Phenylalanine B) Tyrosine C) Tryptophan D) 4-Hydroxyproline E) Asparigine Ans: C Topic: Amino Acid Structure 26. Which of these natural amino acids contains an imidazole ring? A) Histidine B) Lysine C) Tryptophan D) 4-Hydroxyproline E) Two of the above Ans: A 910 Chapter 24 Topic: Amino Acid Structure 27. Which of these natural amino acids contains an –OH group? A) Serine B) Threonine C) Tyrosine D) Two of these E) All of these Ans: E Topic: Amino Acid Structure 28. Which of these natural amino acids, when present in a polypeptide, is likely to exhibit significant hydrogen bonding through its side chain? A) Serine B) Threonine C) Tyrosine D) Two of these E) All of these Ans: E Topic: Amino Acid Structure 29. Which of these natural amino acids, when present in a polypeptide, is not likely to exhibit significant hydrogen bonding through its side chain? A) Leucine B) Threonine C) Tyrosine D) Serine E) All of these are likely to exhibit significant hydrogen bonding through the side chain Ans: A 911 Chapter 24 Topic: Amino Acid Structure 30. Which amino acid is least likely to be found in a natural protein? H CO2H H CO2 H3N CO2 H H3N H NH2 CH3 CH2OH I II III CO2 CO2 H NH3 H3N CH3 CH2C6H5 IV A) B) C) D) E) Ans: H V I II III IV V D Topic: Amino Acid Structure 31. Which amino acid is unlikely to be found in a natural protein? CO2 H3N H3N H CO2 H3N H CH3 CH2OH CH2C6H5 I II III CO2 CO2 H NH3 CH2SH IV A) B) C) D) E) Ans: CO2 H H3N H H V I II III IV V D 912 Chapter 24 Topic: Amino Acid Structure 32. Which of these amino acids is formed from a precursor amino acid only after the latter has been incorporated into a polypeptide chain? A) Serine B) Arginine C) Isoleucine D) Tryptophan E) Hydroxyproline Ans: E Topic: Amino Acid Structure 33. Which of these amino acids is described as an “essential” amino acid? A) Methionine B) Phenylalanine C) Isoleucine D) Tryptophan E) All of these are “essential” amino acids Ans: E Topic: Amino Acid Structure 34. Which of these amino acids is described as an “essential” amino acid? A) Threonine B) Glycine C) Tyrosine D) Serine E) All of these are “essential” amino acids Ans: A Topic: Amino Acid Structure 35. Pipecolic acid logically would be substituted for which natural amino acid in the synthesis of peptide analogs? NH Pipecolic acid CO2H A) B) C) D) E) Ans: Histidine Proline Tryptophan Phenylalanine Tyrosine B 913 Chapter 24 Topic: Amino Acid Structure 36. Logically, the following “unnatural” amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs? HO CO2H NH2 A) B) C) D) E) Ans: Tyrosine Proline Tryptophan Phenylalanine Tyrosine A Topic: Amino Acid Structure 37. Logically, the following “unnatural” amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs? CO2H HS A) B) C) D) E) Ans: NH2 Methionine Cysteine Cystine Tyrosine It could be substituted for all of these amino acids D Topic: Amino Acid Structure 38. Logically, the following “unnatural” amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs? HO2C CO2H NH2 A) B) C) D) E) Ans: Aspartic acid Glutamine Lysine Asparagine Glutamic acid E 914 Chapter 24 Topic: Amino Acid Structure 39. Logically, the following “unnatural” amino acid would be substituted for which natural amino acid in the synthesis of peptide analogs? CO2H H2N NH2 A) B) C) D) E) Ans: Leucine Lysine Arginine Alanine Valine B Topic: Synthesis and Reactions of Amino Acids 40. What product would be obtained upon treating alanine with the following reagent ? O O Cl O O CO2 O NH3 O NH3 I II III O N H CO2H O NH2 IV A) B) C) D) E) Ans: N H V I II III IV V C 915 CO2H Chapter 24 Topic: Synthesis and Reactions of Amino Acids 41. Which of the following would provide a synthesis of alanine? A) CH2=CHCH2OH, HBr, CrO3/H2SO4/H2O; then xs NH3 B) Potassium phthalimide, ClCH2CO2C2H5; then KOH/H2O; then HCl C) Potassium phthalimide, C6H5CH2Br; then KOH/H2O; then CO2,H3O+ D) CH3CH2COOH, (C6H5)3CNa; then NH3 E) Answers A) and B) Ans: A Topic: Synthesis and Reactions of Amino Acids 42. Which of the following would provide a synthesis of valine? A) (CH3)2C=CHCH2OH, HBr/peroxides; CrO3/H2SO4/H2O; then xs NH3 B) Potassium phthalimide, (CH3)2CHCHClCO2C2H5; then KOH/H2O; then HCl C) Potassium phthalimide, (CH3)2CHCH2Br; then KOH/H2O; then CO2,H3O+ D) CH3CH2COOH, (C6H5)3CNa; then NH3 E) Answers A) and B) Ans: A Topic: Synthesis and Reactions of Amino Acids 43. Which of the following would provide a synthesis of leucine? A) (CH3)2C=CHCH2OH, HBr/peroxides, CrO3/H2SO4/H2O; then excess NH3 B) Potassium phthalimide, BrCH(CO2C2H5)2; (CH3)2CHCHClCO2C2H5; then KOH/H2O; then HCl (85%), heat C) Potassium phthalimide, BrCH(CO2C2H5)2; (CH3)2CHCH2Br; then KOH/H2O; then HCl (85%), heat D) (CH3)2CHCOOH, PCl5; then NH3 E) Answers A) and C) Ans: C Topic: Synthesis and Reactions of Amino Acids 44. Which of the following would provide a synthesis of phenylalanine? A) Phenylacetaldehyde, NH3, HCN; H3O+, heat B) Potassium phthalimide, BrCH(CO2C2H5)2; C6H5CH2Br; then KOH/H2O; then HCl (85%), heat C) Potassium phthalimide, (C6H5)CH2CH2Br; then KOH/H2O; then HCl (85%), heat D) C6H5CH2COOH, SOCl2; then NH3 E) Answers A) and B) Ans: E 916 Chapter 24 Topic: Synthesis and Reactions of Amino Acids 45. What product(s) would you expect from the following reaction? Tyrosine + Br2 (excess) H2O ? Br CO2 HO Br CO2 Br NH3 CO2 NH3 HO NH3 Br Br I II III Br O CO2 Br NH3 HO NH3 HO IV A) B) C) D) E) Ans: V I II III IV V B Topic: Synthesis and Reactions of Amino Acids 46. Why is this sequence, CH2=CHCH2OH + HBr, then CrO3/H2SO4/H2O, finally xs NH3, not a good method for the preparation of L-alanine? A) NH3 is not sufficiently nucleophilic to perform the final step. B) HBr does not add to substituted alkenes. C) 1° alcohols are not oxidized by CrO3 in acidic solution. D) Initial HBr addition produces a racemic intermediate which leads to racemic product. E) Steric hindrance precludes nucleophilic substitution at a 2° carbon atom. Ans: D 917 Chapter 24 Topic: Synthesis and Reactions of Amino Acids 47. What products would you expect from the following reaction? O O H2 Pd N H A) OH B) O + ? N H + CO2 + H2N C) O O D) O N H E) OH + H2N + CO2 + H2N Ans: B Topic: Synthesis and Reactions of Amino Acids 48. Which is an isolable intermediate in the Strecker synthesis of an amino acid? X R CO2H I R R CN II NH2 R CHO IV A) B) C) D) E) Ans: NH2 NH2 OH III CO2 NH CO2 R CO2 O V I II III IV V B 918 Chapter 24 Topic: Protein Structure 49. The primary structure of a protein refers to its: A) sequence of amino acid residues. B) disulfide bonds. C) helical structure. D) hydrogen bonding. E) All of these Ans: A Topic: Protein Structure 50. The secondary structure of proteins is derived from: A) peptide linkages. B) disulfide linkages. C) hydrogen bond formation. D) hydrophobic interactions. E) acid-base interactions. Ans: C Topic: Protein Structure 51. Which attractive force is responsible for maintaining the tertiary structure of a protein? A) Disulfide linkages B) Hydrogen bonds C) van der Waals forces D) Hydrophobic interactions E) All of these Ans: E Topic: Protein Structure 52. The occurrence of this amino acid in a polypeptide chain disrupts an ∝-helix: A) Proline B) Alanine C) Methionine D) Histidine E) Tyrosine Ans: A Topic: Protein Structure 53. Disulfide bonds in proteins: A) result from an oxidation of thiols. B) help to maintain the shape of proteins. C) can be broken by reduction. D) can link two cysteine amino acid residues. E) All of the above Ans: E 919 Chapter 24 Topic: Protein Structure 54. Which of these amino acid residues is expected to prefer the interior of a protein to the exterior when the protein is in aqueous medium? A) Threonine B) Valine C) Serine D) Aspartic acid E) Lysine Ans: B Topic: Protein Structure 55. A "conjugated protein" is one which: A) possesses catalytic properties. B) is a digestive enzyme. C) exists largely as an ∝-helix. D) contains unsaturated amino acids. E) contains a nonprotein group as part of the molecule. Ans: E Topic: Peptide Sequencing, Labeling, and Synthesis 56. A pentapeptide has the molecular formula: Asp, Glu, His, Phe, Val. Partial hydrolysis of the pentapeptide gives: Val·Asp, Glu·His, Phe·Val, and Asp·Glu. What is the amino acid sequence of the pentapeptide? A) Phe·Val·Asp·Glu·His B) His·Glu·Asp·Val·Phe C) Asp·Glu·His·Phe·Val D) Phe·Val·Glu·His·Asp E) Glu·His·Phe·Val·Asp Ans: A Topic: Peptide Sequencing, Labeling, and Synthesis 57. A heptapeptide Ala2, Glu, Phe, Pro, Tyr, Val gives labeled alanine when heated with DNFB followed by hydrolysis. On partial hydrolysis the unlabeled heptapeptide gives the following: Ala·Glu, Pro·Tyr, Ala·Val, Tyr·Ala, Val·Phe·Pro. What is the amino acid sequence of the heptapeptide? A) Ala·Phe·Pro·Tyr·Ala·Glu·Val B) Ala·Val·Phe·Pro·Tyr·Ala·Glu C) Ala·Val·Phe·Pro·Tyr·Glu·Ala D) Ala·Val·Phe·Tyr·Pro·Ala·Glu E) Val·Ala·Phe·Tyr·Pro·Ala·Glu Ans: B 920 Chapter 24 Topic: Peptide Sequencing, Labeling, and Synthesis 58. When the pentapeptide below is heated first with 2,4-dinitrofluorobenzene (and base) and then subjected to acidic hydrolysis, which amino acid will bear the dinitrophenyl group? Leu·Val·Gly·Phe·Ile A) Leucine B) Valine C) Glycine D) Phenylalanine E) Isoleucine Ans: A Topic: Peptide Sequencing, Labeling, and Synthesis 59. The Edman degradation uses this reagent to identify the N-terminal amino acid of a peptide or protein. A) C6H5NHNH2 B) C6H5NH2 C) C6H5N=C=S D) C6H5N=C=O E) Aminopeptidase Ans: C Topic: Peptide Sequencing, Labeling, and Synthesis 60. Which amino acid of a polypeptide would become labeled when the polypeptide is treated with 2,4-dinitrofluorobenzene in base, even though the amino acid is not a terminal amino acid? A) Lysine B) Glycine C) Alanine D) Phenylalanine E) Leucine Ans: A Topic: Peptide Sequencing, Labeling, and Synthesis 61. The purple color of the anion formed in the ninhydrin test for ∝-amino acids is due to: A) the attraction of the anion to a metal in a pi-complex. B) intermolecular hydrogen bonding. C) molecular vibrations. D) the highly conjugated nature of the anion. E) the color of the ninhydrin. Ans: D 921 Chapter 24 Topic: Peptide Sequencing, Labeling, and Synthesis 62. Which one of these amino acids does not give the usual purple color with ninhydrin? A) Histidine B) Proline C) Tryptophan D) Leucine E) Aspartic acid Ans: B Topic: Peptide Sequencing, Labeling, and Synthesis 63. This reagent is used to "protect" the amino group of an amino acid which is to be joined to a second amino acid by a peptide bond. O A) Cl O B) C6H5 Cl O C) C6H5 O O D) C6H5 Cl O O C6H5 O E) O Cl Ans: C Topic: Peptide Sequencing, Labeling, and Synthesis 64. Which of these is used to convert a protein into smaller, more manageable fragments for subsequent structural studies? A) Insulin B) Aminopeptidase C) Carboxypeptidase D) Trypsin E) 2,4-Dinitrofluorobenzene Ans: D Topic: Peptide Sequencing, Labeling, and Synthesis 65. How many different tripeptides can exist, each containing one residue of glycine, one of L-threonine, and one of L-arginine? A) 2 B) 3 C) 6 D) 8 E) 9 Ans: C 922 Chapter 24 Topic: Peptide Sequencing, Labeling, and Synthesis 66. What use is made of dicyclohexylcarbodiimide (DCC) in peptide synthesis? A) DCC "protects" the amino group of the intended N-terminal amino acid. B) DCC activates the carboxyl group of one amino acid so that this amino acid reacts more readily with a second amino acid. C) DCC cleaves the blocking groups from the final peptide. D) DCC is the resin used in the automated synthesis of peptides. E) DCC removes the peptide from the resin at the conclusion of the synthesis. Ans: B Topic: Peptide Sequencing, Labeling, and Synthesis 67. Which is an incorrect statement concerning the tetrapeptide L-arginine-L-leucine-Lcysteine-L-phenylalanine? A) This peptide would have an isoelectric point greater than 6.0. B) The peptide will be modified by mild oxidizing agents. C) Trypsin will catalyze preferentially the hydrolysis of the arginine-leucine peptide bond. D) Hydrolysis in dilute aqueous NaOH would lead to racemization of all four amino acids. E) All peptide bonds will be cleaved by refluxing with 6 M HCl for 24 hours. Ans: D Topic: Stereochemistry 68. Which of these amino acids has the R configuration at the stereogenic center but, nonetheless, is an L amino acid? CO2 H3N H3N H CO2 H3N H CH2SH CH2OH CH2C6H5 I II III CO2 H3N CO2 H CH2CH2SCH3 IV A) B) C) D) E) Ans: CO2 H H3N H CH2CO2H V I II III IV V A 923 Chapter 24 Topic: Stereochemistry 69. Which of these amino acids cannot be described as an L amino acid? H2N H CO2H H HO2C I CO2H H2N H H NH2 II III H NH2 HO2C H IV A) B) C) D) E) Ans: NH2 HO2C OH V I II, IV and V I and III II and IV III and V E Topic: Stereochemistry 70. Which of these amino acids is a D amino acid? H2N CO2H H H HO2C I CO2H H2N H H NH2 II III H NH2 HO2C OH IV A) B) C) D) E) Ans: NH2 HO2C H V I II III IV V E 924 Chapter 24 Topic: Stereochemistry 71. Which of these amino acids is an R amino acid? CO2H H H2N I H HO2C C6H5 CO2H H2N H H NH2 II III O H NH2 HO2C HS NH IV A) B) C) D) E) Ans: H OH V II and IV IV and V I and III V All of these are R amino acids B Topic: Stereochemistry 72. Which of the following amino acids is theoretically capable of existing in diastereomeric forms? CO2 CO2 NH3 NH3 Glycine Alanine I II NH3 Threonine III CO2 CO2 NH3 NH2 Leucine Proline IV A) B) C) D) E) Ans: CO2 HO V I II III IV V C 925 Chapter 24 Topic: Stereochemistry 73. Which amino acid is achiral? CO2 CO2 NH3 NH3 Glycine Alanine I II NH3 Threonine III CO2 CO2 NH3 NH2 Leucine Proline IV A) B) C) D) E) Ans: CO2 HO V I II III IV V A SHORT ANSWER QUESTIONS Topic: Protein Structure 74. The exact sequence of the different α-amino acids along the protein chain is called the ________________ of the protein. Ans: primary structure Topic: Henderson-Hasselbach Equation 75. The Henderson-Hasselbach equation shows that the ________________ of an acid is the ________________ at which the acid is half-neutralized. Ans: pKa , pH Topic: Protein Structure 76. The folding of the polyamide chain gives rise to higher levels of complexity called the _______________ and ______________ of the protein. Ans: secondary; tertiary structures Topic: Amino Acid Structure 77. The 22 α-amino acids can be subdivided into three different types on the basis of the structures of their side chains. These three types are: ____________. Ans: neutral, acidic, basic 926 Chapter 24 Topic: Isoelectric Point 78. The pH at which the concentration of the zwitterionic form (dipolar form) of an amino acid is at its highest and the concentrations of the cationic and anionic forms are equal is called the _____________. Ans: isoelectric point Topic: Strecker Synthesis 79. Amino acids can be prepared from aldehydes by treatment with ammonia and HCN followed by hydrolysis. This method is known as the ___________. Ans: Strecker synthesis Topic: Analysis 80. A reagent that reacts with most amino acids to give an intense purple color is called ___________. Ans: ninhydrin Topic: Analysis 81. The most widely used method for identifying the N-terminal amino acid in a peptide chain is called the ____________. Ans: Edman degradation Topic: Analysis 82. C-terminal amino acids can be identified through the use of _____________. Ans: digestive enzymes or carboxypeptidases Topic: Glucose Metabolism 83. The hormone that regulates glucose metabolism is called ______________. Deficiency of this hormone is the major cause of __________. Ans: insulin; diabetes Topic: Peptide Synthesis 84. Peptide synthesis has four basic steps. These are: Ans: protect the N-terminus, activate the carboxylic acid, react with a different amine to form the peptide bond, deprotect the N-terminus Topic: Protein Structure 85. The secondary structure of proteins has three basic types of folding patterns. These are: Ans: α-helices, β-pleated sheets, turns Topic: Enzymes 86. All reactions that occur in living cells are mediated by biological catalysts called ___________. The prevailing hypothesis for enzyme catalysis is called the ____________ hypothesis. Ans: enzymes; lock-and-key 927 Chapter 24 Topic: Analysis 87. One common method of analysis used to measure the approximate molecular weight of a protein is called _____________. Ans: gel electrophoresis Topic: Proteomics 88. The study of all proteins that are expressed in a cell at a given time is called ___________. Ans: proteomics Topic: Anticancer Protein 89. A naturally occurring protein called ___________ acts as a tumor suppressant by coordinating a complex set of responses to changes in DNA, halting abnormal growth in normal cells. Ans: p53 Topic: Dipolar Ions 90. Draw structures to represent what happens when valine is dissolved in a strongly acidic solution (pH=0). O O O Ans: H3O+ OH OH O (pH = 0) NH2 NH3 NH3 Dipolar ion Valine Cationic form Topic: Dipolar Ions 91. Draw structures to represent what happens when valine is dissolved in a strongly basic solution (pH=14). O O O Ans: OH− OH NH2 Valine O NH3 Dipolar ion 928 (pH = 14) O NH2 Anionic form Chapter 24 Topic: Dipolar Ions 92. Draw structures to represent what happens when lysine is dissolved in a strongly acidic solution (pH=0). O O Ans: H2N H3N OH NH2 O NH2 Lysine Dipolar ion H3O+ (pH = 0) O H3N OH NH3 Cationic form Topic: Dipolar Ions 93. Draw structures to represent what happens when lysine is dissolved in a strongly basic solution (pH=14). O O Ans: H2N H3N OH NH2 O NH2 Lysine Dipolar ion OH− (pH = 14) O H2N O NH2 Anionic form 929 Chapter 24 Topic: Synthesis and Reactions 94. What is the final product formed when potassium phthalimide is subjected to the following reaction sequence? Give structural details of all significant intermediates, including stereochemistry, as applicable. i. BrCH(CO2H5)2 O ii. NaOEt, C6H5CH2Br N K ? iii. NaOH O iv. HCl, heat O O Ans: CO2Et BrCH(CO2H5)2 N K N O O CO2Et NaOEt C6H5CH2Br CO2 O C6H5 N H CO2 CO2 O NaOH N O CO2Et CH2C6H5 CO2Et HCl, heat CO2H CO2H + CO2 + CO2H H2N C6H5 DL-Phenylalanine Topic: Strecker Synthesis 95. Give the structure of the aldehyde which, upon treatment with HCN and ammonia, followed by heating with aqueous acid, would afford racemic tryptophan. What is this strategy for the synthesis of α-amino acids called? Ans: This is called the Strecker synthesis O N H 930 Chapter 24 Topic: Amino Acid Synthesis 96. What is the final product formed via the following reaction sequence? Give structural details of all significant intermediates. CO2Et i. CH =CHCN, NaOEt, EtOH 2 HN ? CO2Et ii. conc HCl, reflux O Ans: HN O CO2Et CO2Et CO2Et CH2=CHCN NaOEt, EtOH HN O CH2CH2CN CO2Et conc HCl reflux CO2H CH3CO2H + CO2 + H2N CO2H DL-Glutamic acid 931 Chapter 24 Topic: Peptide Synthesis 97. Suggest a reasonable strategy for the synthesis of the dipeptide Leu-Phe, using established protocol for peptide synthesis. O Ans: O H3N O Cl O O O OH , 25oC N H O O Leu i. Et3N ii. ClCO2Et O H3N O O N H H N O O O OH O O (Phe) H2,Pd H N H3N O O + CO2 + O Leu-Phe 932 N H O O OEt O Chapter 24 Topic: Peptide Structure 98. Draw the structure of the following tripeptide (starting with the N-terminal residue and ending with the C-terminal residue), showing stereochemical details: Gly-Phe-Met Ans: S H H O H N H3N O H N H H O O Gly-Phe-Met Topic: Peptide Structure 99. Draw the structure of the following tripeptide (starting with the N-terminal residue and ending with the C-terminal residue), showing stereochemical details: Ala-Ser-Leu Ans: H3C H O H N H3N O H H N H O O HO Ala-Ser-Leu 933 Chapter 24 Topic: Peptide Structure 100. Draw the structure of the following tripeptide (starting with the N-terminal residue and ending with the C-terminal residue), showing stereochemical details: Val-Trp-Asn O Ans: NH2 H H3N O O H N H N H H O O N H Val-Trp-Asn 934 Chapter 25 MULTIPLE CHOICE QUESTIONS Topic: The Double Helix 1. What is the secondary structure of DNA? A) An alpha-helix B) A pleated sheet C) A flat sheet D) A double helix E) A random coil Ans: D Topic: The Double Helix 2. Which is an incorrect statement concerning the DNA double helix? A) The sugar-phosphate backbone is on the outside of the helix and the base pairs are on the inside. B) The two strands are identical but proceed in opposite directions. C) Hydrogen bonding holds together the two strands. D) Only purine-pyrimidine base pairs can be accommodated. E) The sugar-phosphate backbone is completely regular. Ans: B Topic: The Double Helix 3. Which is an incorrect statement concerning the DNA double helix? A) The sugar-phosphate backbone is on the inside of the helix and the base pairs are on the outside. B) The two strands are identical but proceed in opposite directions. C) The two strands are linked by glycosidic bonds. D) Two of the above statements are incorrect. E) All of the above statements are incorrect. Ans: E Topic: DNA Structure 4. Which is an incorrect statement concerning DNA structure? A) The base and the phosphate units are linked by phosphodiester bonds. B) The sugar and the phosphate units are linked by hydrogen bonds. C) The base and the sugar units are linked by β-N-glycosidic bonds. D) Two of the above statements are incorrect. E) All of the above statements are incorrect. Ans: D 1 Chapter 25 Topic: DNA Structure 5. Which is a correct statement concerning DNA structure? A) The base and the phosphate units are linked by hydrogen bonds. B) The sugar and the phosphate units are linked by phosphodiester bonds. C) The base and the sugar units are linked by β-N-glycosidic bonds. D) Two of the above statements are correct. E) None of the above statements are correct. Ans: D Topic: DNA Structure 6. The analytical data for DNA samples which led to generalizations such as (%G + %A) ≈ (%C + %T) came from the research of what individual? A) James Watson B) Francis Crick C) Edwin Chargaff D) Arthur Kornberg E) Maurice Wilkins Ans: C Topic: DNA Structure 7. Which bases pair in DNA by hydrogen bonding? A) Cytosine and thymine B) Cytosine and uracil C) Adenine and guanine D) Adenine and thymine E) Adenine and uracil Ans: D Topic: DNA Structure 8. In DNA, thymine can pair via hydrogen bonding to _________? A) Cytosine B) Uracil C) Adenine D) Guanine E) Deoxyribose Ans: C 2 Chapter 25 Topic: DNA Structure 9. In DNA, cytosine can pair via hydrogen bonding to _________? A) Deoxyribose B) Uracil C) Adenine D) Guanine E) All of the above Ans: D Topic: DNA Structure 10. In DNA, adenine can be linked to _________ . A) Deoxyribose via β-N-glycosidic bonds B) Uracil via hydrogen bonds C) Phosphate via phosphodiester bonds D) Guanine via amide bonds E) All of the above Ans: A Topic: RNA Structure 11. In RNA, adenine can be linked to _________ . A) Deoxyribose via β-N-glycosidic bonds B) Uracil via hydrogen bonds C) Phosphate via phosphodiester bonds D) Guanine via amide bonds E) All of the above Ans: B Topic: The Double Helix 12. In DNA, the lactim form of guanine will pair with which base? A) Cytosine B) Adenine C) Uracil D) Thymine E) No pairing is possible. Ans: D 3 Chapter 25 Topic: The Double Helix 13. Consideration of tautomerism in guanine suggests that it can exist in lactam and lactim forms. The form that is typically found in DNA is __________, typically pairs with _____________, while the other form is likely to pair with __________, leading to the possible spontaneous mutations. A) Lactam, cytosine, thymine B) Lactam, cytosine, adenine C) Lactim, cytosine, thymine D) Lactam, uracil, cytosine E) Lactim, cytosine, thymine Ans: A Topic: The Double Helix 14. Consider the effect of nitrous acid on the adenine residue of a DNA strand. The product now resembles __________, and is likely to pair with __________, instead of with ___________, leading to the possible mutations. A) guanine, cytosine, thymine B) thymine, cytosine, guanine C) thymine, guanine, cytosine D) uracil, cytosine, guanine E) cytosine, guanine, thymine Ans: A Topic: The Double Helix 15. Which is the predominant tautomeric form of cytosine when it is present in DNA? NH NH2 I A) B) C) D) E) Ans: NH N N N H O N II N O N O III I II III None of these I, II and III are present in approximately equal amounts. A 4 Chapter 25 Topic: The Double Helix 16. The following structure represents the less common (in DNA, at least) tautomeric form of __________. OH H3C N N A) B) C) D) E) Ans: O Cytosine Thymine Adenine Guanine Uracil B Topic: DNA Structure 17. Which is the predominant tautomeric form of guanine when it is present in DNA? O N N H OH N NH N N H NH2 I N NH2 O N N II H N OH N N N NH2 NH III O N IV A) B) C) D) E) Ans: N H N N H N N H NH2 V I II III IV V A 5 NH2 Chapter 25 Topic: DNA Structure 18. Which is the predominant tautomeric form of adenine when it is present in DNA? NH2 NH2 N N H N N N H N H CH3 I N NH2 N N II H N NH2 N N N IV A) B) C) D) E) Ans: N H N N O III NH N N H NH N V I II III IV V B Topic: Sequencing 19. In DNA sequencing, what is used to convert DNA molecules into smaller, more manageable fragments? A) DNA polymerase B) Dilute HCl C) Trypsin D) Chymotrypsin E) Restriction endonucleases Ans: E Topic: Sequencing 20. Separation of the fragments produced in the chemical sequencing of a DNA segment is achieved by the use of which of these techniques? A) Column chromatography B) Fractional distillation C) Thin layer chromatography D) Gas chromatography E) Gel electrophoresis Ans: E 6 Chapter 25 Topic: Sequencing 21. If the base sequence along a segment of DNA were G—C—C—A—T, what would be the base sequence of messenger RNA synthesized from this sequence? A) G—C—C—A—T B) C—G—G—T—A C) C—G—G—U—A D) G—C—C—A—U E) A—T—T—G—C Ans: C Topic: Sequencing 22. The antisense nucleotide G—A—C—T—C, could be synthesized via a __________ template on ________? A) T—C—A—G—A , RNA B) C—T—G—A—G, DNA C) C—T—G—A—G, RNA D) G—A—C—T—U, DNA E) A—G—T—C—T, RNA Ans: B Topic: Sequencing 23. If the base sequence along a segment of DNA were T—C—G—T—A, what would be the antisense oligonucleotide synthesized from this sequence? A) G—C—C—A—T B) C—G—G—T—A C) U—G—C—U—T D) A—G—C—A—U E) A—G—C—A—T Ans: E Topic: Sequencing 24. If the base sequence along a segment of DNA were G—C—C—A—T, what would be the base sequence of messenger RNA synthesized from this sequence? A) C—U—U—T—A B) C—G—G—T—A C) C—G—G—U—A D) G—C—C—A—U E) A—T—T—G—C Ans: C 7 Chapter 25 Topic: Sequencing 25. During translation, the segment on the mRNA that corresponds to the base sequence C—G—A along a gene segment of DNA, would bind to the anticodon __________ on a tRNA. A) A—U—C B) G—C—U C) U—T—C D) G—C—T E) C—G—A Ans: E Topic: Assorted Reactions 26. Complete hydrolysis of adenylic acid would yield which of these? A) Adenosine and a phosphate ion B) Adenine, D-ribose, and a phosphate ion C) Adenine and D-ribose D) Adenine and 2-deoxy-D-ribose E) A pyrimidine, a pentose, and a phosphate ion Ans: B Topic: Nucleotide Synthesis 27. Supply the missing reagent in the following synthesis. HO O HO base + ? H3O OH OH O H3C A) B) C) D) E) Ans: base O + (CH3)2C=O HOCH2CH2OH CH3CHOHCH3 CH3CCl2CH3 CH3CHClCH3 A 8 O CH3 Chapter 25 Topic: Nucleotide Synthesis 28. Supply the missing reagent(s) in the synthesis below. O HO O base O A) B) C) pyridine O H3C base O + ? O P(OCH2C6H5)2 O CH3 H3C O CH3 PO4-3 and C6H5CH2OH PO4-3 and C6H5CH2Cl O P(OCH2C6H5)2 Cl D) C6H5CH3 + POCl3 E) C6H5CH2OH + H3PO4 Ans: C Topic: Assorted Reactions 29. The synthesis of adenosine by the reaction shown below likely occurs by what reaction mechanism? NH2 Cl N N R N N NH3 N N R N N ( R = ribofuranosyl ) A) An SN2 reaction B) An SNAr reaction C) An elimination-addition reaction D) An SN1 reaction E) An E2 reaction Ans: B 9 Chapter 25 Topic: Assorted Reactions 30. The action of nitrous acid on 5-methylcytosine produces which nitrogen base? NH2 H3C N N H O 5-methylcytosine A) Adenine B) Guanine C) Cytosine D) Thymine E) Uracil Ans: D Topic: Assorted Reactions 31. An RNA nucleoside will undergo hydrolysis in dilute acid to yield which of the following? A) 2-Deoxy-D-ribose and a heterocyclic base B) 2-Deoxy-D-ribose, a heterocyclic base, and phosphate ion C) D-Ribose and a heterocyclic base D) D-Ribose, a heterocyclic base, and phosphate ion E) D-Ribose and phosphate ion Ans: C Topic: Assorted Reactions 32. Which are the products of hydrolysis of a RNA nucleotide? A) D-Ribose, adenine B) D-Ribose, guanine, phosphate C) D-Ribose, thymine, phosphate D) 2-Deoxy-D-ribose, cytosine, phosphate E) 2-Deoxy-D-ribose, adenine Ans: B Topic: Assorted Reactions 33. Hydrolysis of DNA from various species gives which of the following results? A) The mole percentage of adenine is approximately equal to that of thymine. B) The mole percentage of cytosine is approximately equal to that of guanine. C) The total mole percentage of purines is approximately equal to that of pyrimidines. D) All of the above E) None of the above Ans: D 10 Chapter 25 Topic: Codons and Anticodons 34. What is the transfer RNA anticodon for the messenger RNA codon, G—C—A? A) T—A—T B) G—U—T C) G—C—A D) A—C—G E) C—G—U Ans: E Topic: Codons and Anticodons 35. Where is the sequence of bases termed an "anticodon" found? A) mRNA B) tRNA C) rRNA D) DNA E) Polysomes Ans: B Topic: Codons and Anticodons 36. If a tRNA anticodon is GUC, what was the original base sequence in DNA? A) GUC B) GTC C) CAG D) GAC E) CTG Ans: B Topic: Codons and Anticodons 37. Which is the messenger codon which calls for the initiation of protein synthesis? A) AUG B) GUA C) UAG D) AUC E) CAC Ans: A Topic: Codons and Anticodons 38. Concerning the genetic code, which of the following is an incorrect statement? A) Not all codons specify amino acids. B) There are a total of 64 different triplets. C) For each amino acid there are the same number of codons. D) The triplet codons are incorporated in messenger RNA. E) The triplet AUG is a "start" codon. Ans: C 11 Chapter 25 Topic: Nucleic Acid Structure 39. The monomeric units of nucleic acids are which of these? A) D-ribose or 2-deoxy-D-ribose B) Phosphate ions C) Purines D) Nucleosides E) Nucleotides Ans: E Topic: Assorted Definitions 40. The primary function of nucleic acids is: A) the catalysis of biochemical reactions. B) the regulation of reactions that occur in the body. C) the preservation, transcription and translation of information. D) the acid-catalyzed hydrolysis of nucleotides. E) the neutralization of nucleic bases. Ans: C Topic: Nucleic Acid Structure 41. A nucleotide unit is composed of: A) a five carbon monosaccharide. B) a phosphate group. C) a heterocyclic base. D) an amino acid. E) A), B) and C) Ans: E Topic: Nucleic Acid Structure 42. A purine: A) contains four nitrogens in the ring system. B) is bicyclic. C) can participate in hydrogen bonding. D) is a heterocyclic base. E) All of the above Ans: E Topic: Nucleic Acid Structure 43. In a nucleotide unit, the components are sequentially linked: A) monosaccharide--phosphate--heterocyclic base. B) amino acid--monosaccharide--phosphate. C) phosphate--monosaccharide--heterocyclic base. D) monosaccharide--amino acid--phosphate. E) heterocyclic base--phosphate--monosaccharide. Ans: C 12 Chapter 25 Topic: Nucleic Acid Structure 44. Which of the following is not a pyrimidine? A) Cytosine B) Thymine C) Guanine D) Uracil E) All of the above are pyrimidines. Ans: C Topic: Nucleic Acid Structure 45. The hydrogen bonding for the base pairs of DNA is between: A) amide carbonyl and -NH2. B) amide N-H and cyclic amine nitrogens. C) alcohols and carbonyls. D) All of these E) Only A) and B) Ans: E Topic: Nucleic Acid Structure 46. Which heterocyclic base found in RNA does not occur in DNA? A) Guanine B) Thymine C) Cytosine D) Uracil E) Adenine Ans: D Topic: Assorted Definitions 47. The formation of a new DNA molecule which is an exact copy of a pre-existing one is designated by what term? A) Duplication B) Transcription C) Translation D) Replication E) Reproduction Ans: D Topic: DNA Mutation 48. Nitrous acid is a suspected mutagen because of its reaction with: A) amine groups. B) monosaccharides. C) phosphates. D) alcohols. E) ketones. Ans: A 13 Chapter 25 Topic: Protein Synthesis 49. The synthesis of proteins according to "the central dogma of molecular genetics" would require: A) replication then translation. B) translation then replication. C) replication then transcription. D) transcription then translation. E) Any of these Ans: D Topic: Protein Synthesis 50. Which is the initial N-terminal amino acid in the developing polypeptide in bacteria? A) Cysteine B) Methionine C) N-Formylmethionine D) Glycine E) Alanine Ans: C Topic: Miscellaneous 51. Which of these has the smallest molecular weight? A) rRNA B) mRNA C) tRNA D) DNA Ans: C Topic: Miscellaneous 52. Which statement concerning the monosaccharide portion of nucleotides is true in every case? A) The monosaccharide is in the pyranose form. B) The linkage to phosphate is at carbon #3. C) The heterocyclic base is attached to carbon #1 of the monosaccharide. D) The monosaccharide - nitrogen base linkage is ∝. E) The monosaccharide is 2-deoxy-D-ribose. Ans: C 14 Chapter 25 Topic: Miscellaneous 53. Relatively short synthetic strands of DNA complementary to certain portions of a gene are known as: A) antisense nucleotides. B) templates. C) palindromes. D) endonucleases. E) polymerases. Ans: A Topic: Transcription 54. The anticodon is part of A) mRNA B) rRNA C) tRNA D) DNA E) None of these Ans: C Topic: Transcription 55. The codon is part of A) mRNA B) rRNA C) tRNA D) DNA E) None of these Ans: A Topic: Transcription 56. The codon consists of A) A sequence of three bases B) A sequence of three amino acids C) A sequence of three purines D) A sequence of three pyrimidines E) None of these Ans: A 15 Chapter 25 Topic: Transcription 57. Specific amino acids attach to the arm of a tRNA that ends in __________, via a(n) _________ bond. A) CCG, ester B) ACG, ether C) CCA, glycosidic D) ACA, amide E) CCA, ester Ans: E Topic: Transcription 58. The time required to synthesize a protein depends on the number of amino acid residues it contains. A rough estimate is that each ribosome can cause _________ peptide bonds to be formed per minute. A) 30 B) 50 C) 100 D) 150 E) 200 Ans: D Topic: Polymerase Chain Reaction 59. Which of the following statements about the polymerase chain reaction are true? A) It generates a large number of copies of DNA B) It polymerizes the short oligonucleotide strands formed during biosynthesis C) It catalyzes the formation of mRNA D) It needs a minuscule sample of DNA E) Two of the above Ans: E Topic: Polymerase Chain Reaction 60. Which of the following is not a valid application of the PCR (polymerase chain reaction) ? A) Semen analysis in forensic investigations B) Evolutionary biology C) Detection of cytomegalovirus D) Prenatal diagnosis of sickle cell anemia E) All of these are valid applications of the PCR Ans: E 16 Chapter 25 SHORT ANSWER QUESTIONS Topic: Protein Synthesis 61. The molecular archive of instructions for protein synthesis is called ______. The molecules that transcribe and translate these instructions are called ______. Ans: DNA; RNA Topic: DNA Structure 62. The four bases that make up the DNA “ladder” are: ____________. Ans: adenine, cytosine, guanine, and thymine Topic: RNA Structure 63. The four bases found in RNA are: _________. Ans: adenine, cytosine, guanine, and uracil Topic: Miscellaneous 64. Each section of DNA that codes for a particular protein is called a _______. Ans: gene Topic: Miscellaneous 65. Amino acids bear the same relation to proteins as __________ do to nucleic acids. Ans: nucleotides Topic: Miscellaneous 66. While proteins are made up of amino acids connected by amide bonds, nucleic acids are made up of nucleotides connected by __________. Ans: phosphate ester linkages Topic: DNA Structure 67. The secondary structure of DNA was proposed by Watson and Crick to be a ___________________. Ans: double helix Topic: DNA Structure 68. In the DNA double helix, two strands of nucleic acids are held together by _____________. Ans: hydrogen bonds Topic: DNA Structure 69. In the DNA base pairs, adenine always bonds with _________ and cytosine with __________. Ans: thymine; guanine 17 Chapter 25 Topic: DNA Structure 70. The backbone of DNA is made up of __________. Ans: sugars and phosphates Topic: Miscellaneous 71. A chemical that causes mutations in DNA is called a _________. Ans: Mutagen Topic: Protein Synthesis 72. Protein synthesis requires that two major processes take place. The first takes place in the cytoplasm involving messenger RNA (mRNA) and is called ___________. The second involves two other types of RNA: __________ and ____________. Ans: transcription; ribosomal RNA [rRNA]; transfer RNA [tRNA] Topic: Protein Synthesis 73. The anticodon is a specific sequence of ____________, found on the ___________, which allows it to bind to the ____________, of _____________. Ans: three bases, tRNA, codon, mRNA Topic: RNA 74. The molecular weight of tRNA is _________, compared with mRNA or rRNA; consequently, the solubility of tRNA is __________. Ans: low, high Topic: RNA 75. The function of tRNA is ___________. Ans: to transport amino acids to specific areas on the mRNA bound to the ribosome Topic: Triplet Code 76. Explain why 3 bases (triplet code) are needed in the genetic code to unambiguously identify each amino acid. Ans: There are only four bases and 20 amino acids; thus, each base could uniquely code for only 4 amino acids. A set of two bases would uniquely code for (42) , i.e., 16 amino acids, still not quite enough. However, if each amino acid were to be coded via a set of three bases, then there could be 64 possible combinations, allowing for redundancies and certain necessary “punctuation” codes, such as start/stop codes, etc. 18 Chapter 25 Topic: DNA Structure 77. Draw structures to represent the hydrogen bonding between adenine and thymine. H Ans: .. :O N H N N N: H N N N O adenine thymine Topic: DNA Structure 78. Draw structures to represent the hydrogen bonding between cytosine and guanine. H Ans: .. O: H N N N :N N H N N N guanine :O .. H H cytosine Topic: DNA Structure 79. Draw structures to represent the hydrogen bonding between adenine and uracil. H Ans: .. :O N H N N N: H N N N O uracil adenine Topic: DNA Structure 80. Draw structures to represent the bonding between deoxyribose and thymine. O Ans: N HO O N H thymine O OH H deoxyribose 19 Chapter 25 Topic: DNA Structure 81. Draw structures to represent the bonding between ribose and uracil. O Ans: H N HO uracil N O O OH OH ribose Topic: DNA Structure 82. Draw the structures to represent what is likely to happen when cyclic AMP (3’,5’-cyclic adenylic acid) reacts with aqueous sodium hydroxide, briefly explaining your rationale. NH2 NH2 Ans: N 5' O N P 3' O HO N O NaOH H2O O O N N HO OH O HO cyclic AMP O N N N OH P O 3'-adenylic acid The reaction appears to follow an SN2 mechanism, with nucleophilic attack by OH− at the primary 5’- position to afford 3’-adenylic acid (rather than at the secondary 3’- position, which would yield 5’-adenylic acid). 20 Chapter 25 Topic: Nucleotide Synthesis 83. Suggest a reasonable strategy for the specific phosphorylation of the 5’ –OH group of a nucleoside. Ans: In order for phosphorylation to occur specifically at the 5’ OH, the 2’- and 3’- OH groups must first be protected. HO HO base O base O acetone H3O+ OH OH O O H3C CH3 O P(OCH2C6H5)2 Cl pyridine O O P(OCH2C6H5)2 O base O P(OCH2C6H5)2 O base O i. H3O+, H2O ii. H2, Pd OH OH O O H3C CH3 Topic: Tautomerism, Mutation 84. Draw the structures of two tautomeric forms of guanine, one a lactam, the other a lactim. Explain the possible involvement of the lactim form in causing spontaneous mutation during replication. Ans: The lactim form resembles adenine and might pair with thymine instead of cytosine, causing the first error in the new DNA strand being synthesized. This mistake, if uncorrected, can then be passed on to the next strand being synthesized from this “mutated” strand, by introducing an adenine residue, where there should be a guanine residue. .. O: OH N N N H N H N N N H N: N H N H H H lactam (likely to pair with cytosine) lactim (likely to pair with thymine) 21 Chapter 25 85. What product is likely to be formed from the reaction between an adenine residue on a nucleotide and nitrous acid? Explain the possible involvement of the product of this reaction in causing spontaneous mutation during replication. Ans: The product resembles a guanine nucleotide, thus might pair with cytosine instead of thymine, causing the first error in the new DNA strand being synthesized. This mistake, if uncorrected, can then be passed on to the next strand being synthesized from this “mutated” strand, by introducing a guanine residue, where there should be an adenine residue. NH2 N N R N O N HNO2 N adenine nucleotide (pairs with thymine) N R NH N hypoxanthine nucleotide (likely to pair with cytosine) 22

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Download 1 MULTIPLE CHOICE QUESTIONS Topic: Atomic Orbitals 1. In