Ch. 4 Key - exercises with answers PDF

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Chapter 4 Organic Compounds: Cycloalkanes and Their Stereochemistry By Dr. Xiangyang Lei 1. Assignments (textbook) Chapter 4 1-62 2. Provide IUPAC names for the following compounds, including the cis- or trans- prefix where appropriate.

(1)

(2)

1-chloro-3-ethyl-5-methylcyclohexane

1-bromo-3-ethyl-2-methylcyclopentane

(3)

(4)

trans-1-bromo-2-methylcyclohexane

4-cyclopropyl-1,1-dimethylcyclohexane

(5)

(6)

cis-1-isopropyl-3-methylcycloheptane

5-bromo-1-tert-butyl-2-chlorocycloheptane

H3C

CH3

3. Draw the structure that corresponds with each name. (1) 1,1-dimethylcyclooctane (2) cis-1-chloro-2-ethylcyclobutane Cl

CH2CH3

or (3) trans-1-sec-butyl-2-ethylcyclohexane

Cl

CH2CH3

(4) 4-bromo-3-cyclobutylheptane

CH2CH3 Br CH3CH2 CH CH CH2CH2CH3

CH CH2CH3 CH3

or

1

4. Draw six cycloalkanes with the formula C5H10 and give their IUPAC names.

5. Draw the two chair conformations of the following compounds, and indicate their relative stabilities. (1) ethylcyclohexane CH2CH3 CH2CH3

H

H eq. more stable

ax. less stable

(2) cis-1,2-dimethylcyclohexane CH3

CH3

H CH3

CH3 H

H ax., eq.

H eq., ax.

same stability

(3) trans-1,2-dimethylcylohexane CH3 H

H

H

CH3 CH3 H eq., eq. more stable

CH3 ax., ax. less stable

(4) cis-1,3-dimethylcyclohexane CH3

CH3 H

CH3

CH3 H

H ax., ax. less stable

H

eq., eq. more stable

(5) trans-1,3-dimethylcylohexane H

CH3 H

H H3C ax., eq.

CH3 CH3

same stability

H

eq., ax.

2

(6) cis-1,4-dimethylcyclohexane CH3 CH3

H

CH3

H

H3C

H H

ax., eq.

eq., ax.

same stability

(7) trans-1,4-dimethylcylohexane CH3

H

H

H

CH3

CH3

CH3 H eq., eq. more stable

ax., ax. less stable

(8) cis-1-t-butyl-4-ethylcyclohexane CH3 CH3 C CH3

CH2CH3

H

H3CH2C

CH3

H

C CH3 CH3

H

H eq.(t-butyl), ax.(ethyl) more stable (larger group equatorial)

ax.(t-butyl), eq.(ethyl) less stable

(9) trans-1-t-butyl-4-ethylcyclohexane CH3 CH3 C CH3 H

H

H CH3 CH3CH2

CH2CH3 ax., ax. less stable

C CH3 H

CH3

eq., eq. more stable

3...