Using the data in Table 3.9, calculate the percentage of molecules of cyclohexanol that have the OH group in an equatorial position at 25 °C.

The A value of a substituent on a cyclohexane ring is essentially the ∆G° for a substituent going from the equatorial to the axial position in a chair–chair interconversion. Because most substituents prefer to be in the equatorial position, A values are, by definition, positive numbers. Use the table of A values to calculate ∆G° and K_eq for the chair–chair interconversions shown.

(d)

The ∆G° for conversion of “axial” fluorocyclohexane to “equatorial” fluorocyclohexane at 25 °C is -0.25kcal/mol. Calculate the percentage of fluorocyclohexane molecules that have the fluoro substituent in an equatorial position at equilibrium.

Why is the percentage of molecules with the substituent in an equatorial position greater for isopropylcyclohexane than for fluorocyclohexane?

The A value of a substituent on a cyclohexane ring is essentially the ∆G° for a substituent going from the equatorial to the axial position in a chair–chair interconversion. Because most substituents prefer to be in the equatorial position, A values are, by definition, positive numbers. Use the table of A values to calculate ∆G° and K_eq for the chair–chair interconversions shown.

(a)

Rank the following compounds in order of their total heat of combustion. These compounds are constitutional isomers, each with a molecular formula of C₆H₁₂.

Which constitutional isomer, A or B, would you expect to have the highest heat of combustion (∆H_combustion)?

Which of the following cycloalkanes would you expect to produce the least heat upon combustion when measured per CH₂? Explain your answer.

Estimate the equilibrium composition of the chair conformers of the following cyclohexanes at room temp:

cis-1,3-diethylcyclohexane