CHEM 237 Quiz 2A Key Name:Dr. Neils Andersen Section:Autumn 2009 TA:

1) The diaxial conformation of cis-1,3 dimethylcyclohexane is approximately 23kJ/mol (5.4 kcal/mol) less stable than the diequatorial conformation. Draw thetwo possible chair conformations and suggest a reason for the large energydifference. (3 pts)

H H

H

H

H

CH3

H

H

H

H

CH3

H

HH

H

H

H

H

H

H3C

H

H

H

CH3

Less stable, 1,3 diaxial interaction

2) Draw the chair conformations of menthol, and circle the one that is more stable.

H

H

OH

H

H

CH(CH3)2H

H

HCH3

H H

H H

H

H

OH

H

H

H

H

CH3

H

H

H

H

H

H

H

H3C

H

H

H

OH

More stable

Axial Equitorial

3) In each of the following sets, circle the compound that has the carbon with thehighest oxidation state. (1 pt each)

a) CH3F or CHF3 or CH2F2

b) H2C CH2 HC CHor

4) Exclusive of compounds with double bonds, five hydrocarbons are constitutionalisomers of cis- and trans-1,2-dimethylcyclobutane. Draw these compounds. (1pteach)

5) Write structural formulas for each of the following alcohols and alkyl halides:(4pts)

a) Cyclobutanol

OH

b) cis-4-tert-Butylcyclohexanol H H

H

H

OH

H

H

H

H

H

H

c) 2,6 Dichloro-4-methyl-4-octanol

H3C OHCl Cl

d) 1-Cyclopropylethylbromide Br

6) Rank the following (a) in terms of heats of combustion and (b) in order ofincreasing stability. (3 pts)

Highest heat of combustionLeast Stable

7) Sight down the C2-C3 bond and draw Newman projection formulas for: (6pts)

a) The two least stable staggered conformations of 2-methylbutane

H

H CH3CH3

HH3CH

H3C HCH3

HH3CLess Stable

b) The two conformations of 2,2-dimethylbutane and indicate which is lessstable

H

H

CH3

CH3

CH3H3CH

H3C HCH3

CH3H3C

Eclipsed, less stable

8) Name each of the following compounds (4 pts)

a) (CH3)2CHCH2CH2CH2Br 1-Bromo-4-Methyl-Pentane

b) Cl3CCH2Br 2-Bromo-1,1,1-Trichloroethane

c)

CH2OH

Cl 2-(1-chloroethyl) pentan-1-ol