Question

The two isomers cis- and trans-4-tert-butyl-2-methylcyclohexanone are interconverted by base treatment. Which isomer do you think is more stable, and why?

Short answer

Cis-4-tert-butyl-2-methylcyclohexanone is more stable.

Step-by-step solution

Isomers cis- and trans-4-tert-butyl-2-methylcyclohexanone

The reaction of cis—4-terbutyl-2-methylcyclohexanone with NaOH undergoes isomerisation.

Isomerisation

Stability of isomer

The cis-isomer is more stable. This is because both substituted groups are at the equatorial position of the cyclohexane ring and cause less 1,3diaxial interaction.

The chair forms of both the isomers are as shown below: