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OUTLINE OF 2nd MIDTERM MATERIAL
Chapter 4: Alkanes (Cycloalkanes) –review from 1st midterm material
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Cyclohexanes: chair and boat forms; equatorial and axial bonds of cyclohexanes
Mono-substituted cyclohexanes: equatorial substituents are more stable (1,3-diaxial
interactions); tert-butylcyclohexane
Disubstituted cyclohexanes: cis/trans-isomerism; comparison of stability (the fewer are
the axial substituents, the more stable is the disubstituted cyclohexane.
Fused rings (cis and trans decalins)
Chapter 5: Stereochemistry
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Stereoisomers (drawing 3-D molecules in “wedged” and “dashed” bonds; Fischer
structures)
Enantiomers (physical properties); chirality; stereogenic (chiral) centers; racemic
mixtures
Optical activity; criteria for optical activity; R/S Configurations
Molecules with more than one stereogenic center; diastereoisomers; molecules with
chiral centers, but with a plane of symmetry (thus optically inactive, “meso” form)
Chapter 6: Understanding Organic Reactions
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Types of organic reactions
Bond formation and bond cleavage (homolytic and heterolytic)
Reactive Intermediates
Bond Dissociation Energies (BDE)
Thermodynamics: Equilibria and free energy changes; enthalpy and entropy
Reaction/Energy Diagrams
Kinetics: Reaction rates
Catalysts/Enzymes
Chapter 7: Alkyl Halides – SN1 and SN2 Reactions
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Nucleophiles (in their free base and anionic forms)
SN2 Reactions (stereochemical outcomes)
When site of attack is a chiral center
When site of attack is not a chiral center
Leaving Group abilities
SN1 Reactions (stereochemical outcomes)
Carbocations; factors which determine carbocation stability
Hammond Postulate
Competition between SN1 and SN2 Reactions
Conditions which favor SN2 reactions: uncrowded reaction site; strong nucleophiles;
aprotic polar solvents
Conditions which favor SN1 reactions: potential to form stable a carbocation (tertiary
alkyl halides); weak, non-ionic nucleophiles
Chapter 8: Alkyl Halides – Dehydrohalogenation (E1, and E2) Reactions
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Site of attack in elimination reactions
Types of bases
Bulky, non-nucleophilic (strong) bases
Weak base nucleophiles
Regioselectivity (and stereoselectivity) in elimination reactions (Zaytzeff Rule)
Stereochemical requirements in E2 reactions (application to cyclic systems)
Competition between Nucleophilic Substitution and Elimination Reactions: SN1, E1
reactions generally occur together
Conditions which favor E2 reactions: more substituted alkyl halides (why?) –in contrast
to SN2 reactions-; bulky bases
Chapter 9: Alcohols and Ethers
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Structural features of alcohols
Syntheses of alcohols through SN reactions
Reactions of alcohols
General Strategy: Converting –OH into a good LG (9.7A)
SN1 type reactions: conversions of 3o alcohols into alkyl halides (9.11A)
SN2 type reactions: Lewis acid –mediated (with SOCl2 and PBr3 -9.12)
E type reactions: dehydration of alcohols (9.8)