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Chem 230 Review
Conformational analysis and cyclohexane conformations (Chpt 4):
1. Use a Newman projection, about the indicated bond, to draw the most stable conformer for the following compounds.
(a) 3-methylpentane about the C2-C3 bond
(b) 3,3-dimethylhexane about the C3-C4 bond
2. Using what you know about conformational energetics of substituted cyclohexanes, predict which of the two decalin isomers (cis or trans) is more stable. Explain you reasoning.
3. The most stable form of the common sugar glucose contains a six-membered ring in the chair conformation with all the substituents equatorial. Draw this most stable conformation of glucose.
Reactive intermediates and their properties (Chpt 5):
4. Draw the Lewis structures of methyl carbanion, methyl carbocation, methyl radical, and methylene carbene. Which is the most electrophilic? Which is the most nucleophilic?
5. Write a mechanism for the light-initiated reaction of cyclohexane with chlorine to give chlorocyclohexane. Draw a reaction-energy diagram for the propagation steps. You can assume that the first propagation step is rate-determining and the overall process is exothermic.
Stereochemistry (Chpt 9):
6. For each structure, star any chiral carbon atoms and label each chiral carbon as (R) or (S).
7. Give the stereochemical relationships (same compound, structural isomers, distereomers, or enantiomers) between each pair of isomers.
8. Consider the following free radical bromination of an enantiomerically pure alkane. Is the product formed as a single enantiomer or a racemic mixture? Is the product optically active or optically inactive? Explain your answers.
Substitution and elimination reactions (Chpt 11):
9. Predict the products of the following reactions.
10. When the following enantiomerically pure alkyl bromide is exposed to sodium phenoxide in DMF, the major product is formed as a single enantiomer; however,
Conformational analysis and cyclohexane conformations (Chpt 4):
1. Use a Newman projection, about the indicated bond, to draw the most stable conformer for the following compounds.
(a) 3-methylpentane about the C2-C3 bond
(b) 3,3-dimethylhexane about the C3-C4 bond
2. Using what you know about conformational energetics of substituted cyclohexanes, predict which of the two decalin isomers (cis or trans) is more stable. Explain you reasoning.
3. The most stable form of the common sugar glucose contains a six-membered ring in the chair conformation with all the substituents equatorial. Draw this most stable conformation of glucose.
Reactive intermediates and their properties (Chpt 5):
4. Draw the Lewis structures of methyl carbanion, methyl carbocation, methyl radical, and methylene carbene. Which is the most electrophilic? Which is the most nucleophilic?
5. Write a mechanism for the light-initiated reaction of cyclohexane with chlorine to give chlorocyclohexane. Draw a reaction-energy diagram for the propagation steps. You can assume that the first propagation step is rate-determining and the overall process is exothermic.
Stereochemistry (Chpt 9):
6. For each structure, star any chiral carbon atoms and label each chiral carbon as (R) or (S).
7. Give the stereochemical relationships (same compound, structural isomers, distereomers, or enantiomers) between each pair of isomers.
8. Consider the following free radical bromination of an enantiomerically pure alkane. Is the product formed as a single enantiomer or a racemic mixture? Is the product optically active or optically inactive? Explain your answers.
Substitution and elimination reactions (Chpt 11):
9. Predict the products of the following reactions.
10. When the following enantiomerically pure alkyl bromide is exposed to sodium phenoxide in DMF, the major product is formed as a single enantiomer; however,