Draw the structure that corresponds with each name.

k. cyclobutylcyclohexane

l. cis-1-bromo-3-chlorocyclohexane

Which of the following cycloalkanes are capable of geometric (cis-trans) isomerism? Draw the cis and trans isomers.

a. 3-ethyl-1,1-dimethylcyclohexane

Which of the following cycloalkanes are capable of geometric (cis-trans) isomerism? Draw the cis and trans isomers.

b. 1-ethyl-3-methylcycloheptane

Which of the following cycloalkanes are capable of geometric (cis-trans) isomerism? Draw the cis and trans isomers.

c. 1-ethyl-3-methylcyclopentane

The heat of combustion of cis-1,2-dimethylcyclopropane is larger than that of the trans isomer. Which isomer is more stable? Use drawings to explain this difference in stability.

trans-1,2-Dimethylcyclobutane is more stable than cis-1,2-dimethylcyclobutane, but cis-1,3-dimethylcyclobutane is more stable than trans-1,3-dimethylcyclobutane. Use drawings to explain these observations.

The cyclohexane chair shown in Figure 3-22 has the headrest to the right and the footrest to the left. Draw a cyclohexane chair with its axial and equatorial bonds, showing the headrest to the left and the footrest to the right.

Draw 1,2,3,4,5,6-hexamethylcyclohexane with all the methyl groups

a. in axial positions.

Draw 1,2,3,4,5,6-hexamethylcyclohexane with all the methyl groups

b. in equatorial positions.

Draw a Newman projection, similar to Figure 3-25 down the C1—C6 bond in the ­equatorial conformation of methylcyclohexane. Show that the equatorial methyl group is also anti to C5. (Using your models will help.)

<IMAGE>

Table 3-6 shows that the axial–equatorial energy difference for methyl, ethyl, and isopropyl groups increases gradually: 7.6, 7.9, and 8.8 kJ/mol (1.8, 1.9, and 2.1 kcal/mol). The tert-butyl group jumps to an energy difference of 23 kJ/mol (5.4 kcal/mol), over twice the value for the isopropyl group. Draw pictures of the axial conformations of isopropylcyclohexane and tert-butylcyclohexane, and explain why the tert-butyl substituent experiences such a large increase in axial energy over the isopropyl group.

Draw the most stable conformation of

a. ethylcyclohexane.

Draw the most stable conformation of

b. 3-isopropyl-1,1-dimethylcyclohexane.

Draw the most stable conformation of

c. cis-1-tert-butyl-4-isopropylcyclohexane.

Name the following compounds. Remember that two up bonds are cis; two down bonds are cis; one up bond and one down bond are trans.

(c)

(d)

Name the following compounds. Remember that two up bonds are cis; two down bonds are cis; one up bond and one down bond are trans.

(e)

(f)

a. Draw both chair conformations of cis-1,4-dimethylcyclohexane, and determine which conformer is more stable.

b. Repeat for the trans isomer.

c. Predict which isomer (cis or trans) is more stable.

Use your results from Problem 3-27 to complete the following table. Each entry shows the positions of two groups arranged as shown. For example, two groups that are trans on adjacent carbons (trans-1,2) must be both equatorial (e,e) or both axial (a,a).

Draw the two chair conformations of each of the following substituted cyclohexanes. In each case, label the more stable conformation.

a. cis-1-ethyl-2-methylcyclohexane

b. trans-1,2-diethylcyclohexane

Draw the two chair conformations of each of the following substituted cyclohexanes. In each case, label the more stable conformation.]

c. cis-1-ethyl-4-isopropylcyclohexane

d. trans-1-ethyl-4-methylcyclohexane

Draw the most stable conformation of

a. cis-1-tert-butyl-3-ethylcyclohexane.

Draw the most stable conformation of

b. trans-1-tert-butyl-2-methylcyclohexane.

Draw the most stable conformation of

c. trans-1-tert-butyl-3-(1,1-dimethylpropyl)cyclohexane.

Name the following compounds.

(a)

(b)

Name the following compounds.

(c)

(d)

Use your models to do a chair–chair interconversion on each ring of the conformation of cis-decalin shown in Figure 3-27. Draw the conformation that results.

a. There are 18 isomeric alkanes of molecular formula C₈H₁₈. Draw and name any eight of them.

Draw and name the six isomeric cyclopentanes of molecular formula C₇H₁₄. These will include four constitutional isomers, of which two show geometric (cis-trans) stereoisomerism.

Which of the following structures represent the same compound? Which ones represent different compounds?

(a)

Which of the following structures represent the same compound? Which ones represent different compounds?

(b)