Question

Which of the following conformers has the highest energy (is the least stable)?

Short answer

Compound B has the highest energy and is the least stable.

Step-by-step solution

Step 1: The stereochemistry of the three conformers.

• All three compounds are diaxial-substituted cyclohexane.
• The two alternative chair conformations formed after a ring flip are not equally stable when a substituent is added to a cyclohexane ring.

The conformer that has the highest energy or is the least stable.

Conformer B has the highest energy and is least stable because:

• It has di-axial interaction between CH₃ and Cl.
• Di-axial interaction between CH₃and Cl is more than between Cl and H or between CH₃ and H.