Question 4.61: trans-1,3-Di-tert-butylcyclohexane exists in a twist boat co......

Organic Chemistry Study Guide: Key Concepts, Problems, and Solutions [1424398]

trans-1,3-Di-tert-butylcyclohexane exists in a twist boat conformation, rather than a chair conformation. Why?

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An axial tert-butyl group exists in the trans isomer, which has a steric repulsion of 22 kJ mole $^{−1}$ (Table 4.6). This repulsion is eliminated in the twist boat conformation, even though it is 22 kJ mole $^{−1}$ less stable than the chair conformation because both tert-butyl groups can occupy equatorial-like positions in this conformation.

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