4. Alkanes and Cycloalkanes

Is each of the following a cis isomer or a trans isomer?

a,

b.

c.

Given the following chair conformations, draw each in its planar form as if you were viewing it from above.

(b)

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).

Which of the following best describes the lowest energy chair conformation of $\text{cis-1-ethyl-2-isopropylcyclohexane}$?

Which of the following is the most stable conformation of $\text{trans-1-isopropyl-3-methylcyclohexane}$?

Draw two different chair conformations for each of the following molecules. Make sure that your drawings clearly show the cis–trans stereochemistry.

(c)

Given the following chair conformations, draw each in its planar form as if you were viewing it from above.

(c)

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)

Which of the following chair conformations represents $\mathrm{trans}-1,2-\mathrm{dimethylcyclohexane}$?

Name the following cycloalkanes using the IUPAC system of nomenclature.

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)

Is each of the following a cis isomer or a trans isomer?

d.

e.

f.

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.