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Chemistry 262 Quiz 2 Winter 2017 The following practice quiz covers Chapter 10 in Loudon & Parise’s Organic Chemistry, 6th ed. and contains 24 questions. Wednesday’s quiz will also contain 24 questions, valued at 1.25 point/question, as well as 3 bonus questions valued at 2 points each Name: _________________________________________________________ ALCOHOL AND THIOL ACID BASE CONSIDERATIONS 1. Which of the following has the highest pKa value in aqueous solution? a. n-butanol b. sec-butyl alcohol c. isobutyl alcohol d. tert-butyl alcohol e. mercaptobutane (butane-1-thiol) ALCOHOL AND THIOL ACID BASE CONSIDERATIONS 2. Which of the following has the lowest pKa value in aqueous solution? a. n-butanol b. sec-butyl alcohol c. isobutyl alcohol d. tert-butyl alcohol e. mercaptobutane (butane-1-thiol) ALCOHOL AND THIOL ACID BASE CONSIDERATIONS 3. Which of the following would be substantially (> 10 %) deprotonated by sodium phenoxide (PhONa) a. tert-butyl alcohol b. Cyclohexanone c. Ethanethiol d. Hydrogen cyanide e. More than one of the above DEHYDRATION OF ALCOHOLS 4. What is the expected outcome when 3-methyl-2-butanol is heated in concentrated H2SO4? a. 3-methyl-2-butanesulfonic acid b. 3-methyl-1-butene c. 2-methyl-1-butene d. 2-methyl-2-butene e. (c) and (d) are equally likely DEHYDRATION OF ALCOHOLS 5. 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 REACTION OF ALCOHOLS WITH HYDROGEN HALIDES 6. 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 BONUS: AN ALTERNATIVE PATHWAY TO DIRECT REARRANGEMENT IS REPETITIVE ELIMINATION AND ADDITION. SHOW HOW THIS COULD EXPLAIN THE FORMATION OF 2-METHYL-2-PENTENE FROM 4-METHYL-2-PENTANOL IN AQUEOUS H2SO4: BASE COMPATABLE ALCOHOL-DERIVED LEAVING GROUPS 7. Which of the following compounds 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 CH3 S CH3 O CH3 O S CH3 O IV V a. I b. II c. III d. IV e. V BASE COMPATABLE ALCOHOL-DERIVED LEAVING GROUPS 8. 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 BASE COMPATABLE ALCOHOL-DERIVED LEAVING GROUPS 9. Methanesulfonic acid, shown immediately below, is treated in turn with PCl5 and (R)-2butanol. Which of the following Fischer formulas is a stereochemically correct representation of the final product? O CH3 S OH, O H CH3 MsO MsO H O CH3 H3C CH2CH3 CH2CH3 S H O CH2CH3 II I O H3C III H S O CH3 O CH3 H3C CH2CH3 IV CH3 S Cl O CH2CH3 V a. I b. II c. III d. IV e. V MODERN METHODS FOR CONVERSION OF ALCOHOLS TO ALKYL HALIDES 10. Consider the conversion of 3-methyl-2-butanol to 2-bromo-3-methylbutane. If a mild tempertature environment is to be maintained, the best reagent is a. Conc. HBr b. Br2 c. NaBr, H2SO4 d. Ph3PBr2 e. HBr, AIBN MODERN METHODS FOR CONVERSION OF ALCOHOLS TO ALKYL HALIDES 11. Please show the mechanism by which benzyl alcohol is converted to benzyl chloride by thionyl chloride (SOCl2) in the presence of pyridine (C5H5N) ORGANIC REDOX REACTIONS 12. List the following compounds in order of increasing oxidation. CH2Cl2 HCOOH CH3OH I II III a. I, II, III b. III, II, I c. II, I, III d. III, I, II e. I, III, II ORGANIC REDOX REACTIONS 13. The following transformation would be considered a(n) CH3Cl a. Reduction b. Oxidation c. Addition d. Elimination e. Rearrangement CH3MgCl OXIDATION OF ALCOHOLS 14. Which of the reagents listed below would efficiently accomplish the transformation of 2-methyl-3-cyclopentenol into 2-methyl-3-cyclopentenone? OH O ? a. KMnO4(aq, alkaline) b. CrO3/H2SO4 c. H2, Pt d. Br2, CCl4 e. Two of the above OXIDATION OF ALCOHOLS 15. With which of the following compounds will CrO3 in aqueous H2SO4 fail to give a positive test? a. CH3CH2CH2CH2OH b. CH3CHCH2CH3 OH c. (CH3)3COH d. H CH3CH2CH2C O e. More than one of the above CHEMICAL AND STEREOCHEMICAL GROUP RELATIONSHIPS 16. To use NMR parlance, protons Ha and Hb are said to be H Cl Hb Ha a. Identical b. Enantiotopic c. Diasterotopic d. Homotopic e. Mesotopic CHEMICAL AND STEREOCHEMICAL GROUP RELATIONSHIPS 17. What is the term best describing the relationship between protons Ha and Hb? Hb Ha a. Homotopic b. Vicinal c. Enantiotopic d. Diastereotopic e. Isomeric CHEMICAL AND STEREOCHEMICAL GROUP RELATIONSHIPS 18. A typical proton NMR experiment does not discriminate enantiotopic protons; it will however distinguish diastereotopic protons. This having been said, how many signals would you expect for the compound shown below (assuming you had an NMR of sufficient resolving capacity)? S a. 4 b. 5 c. 6 d. 7 e. 8 S OCTET EXPANSION AND OXIDATION OF THIOLS 19. Which of the following is most oxidized? a. CH3CH2SH b. CH3CH2SCH2CH3 c. CH3CH2SSCH2CH3 d. CH3SO2Cl e. (CH3)2SO OCTET EXPANSION AND OXIDATION OF THIOLS 20. How many non-bonded pairs of electrons are associated with the sulfur in DMSO (dimethyl sulfoxide)? a. 4 b. 3 c. 2 d. 1 e. 0 SYNTHESIS OF ALCOHOLS 21. What principal product(s) would you expect from the following reaction sequence? CH3 1. BH3-THF ? 2. H2O2, NaOH CH3 CH3 OH CH3 O OH + enantiomer I a. I b. II c. III d. IV e. V H3C II CH2OH OH + enantiomer + enantiomer III IV V SYNTHESIS OF ALCOHOLS 22. What principal product(s) would you expect from the following reaction sequence? CH3 1. Hg(OOCCH3)2 THF, H2O ? 2. NaBH4, NaOH CH3 CH3 CH2OH OH HO CH3 CH3 OH OH I II III IV V a. I b. II c. III d. IV e. V RETROSYNTHETIC ANALYSIS 23. You are tasked with synthesizing 2-phenyl-2-hexanol via a Grignard reaction. What pair(s) of compounds would make effective starting materials? a. O Br and b. CH3CHCH2Br O and CH3CC6H5 CH3 c. O CH3CH2CH2CH2CCH3 d. (a) or (b) e. (a) or (c) and C6H5Br RETROSYNTHETIC ANALYSIS 24. 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 + H2SO4/140C d. Ethanol + NaH, then HCHO, then H3O+, then HBr, then Mg/ether, then CH3CH2CH2Br e. Ethanol + H2SO4/180°C, then CH3CH2CH2Br