Question

The most stable conformation of trans-1,4-dimethylcyclohexane is represented as:

• A.
• B.
• C.
• D.

Answer 1

The correct option is C

In chair conformation of cyclohexane we have two position in the conformer.
1. Axial position
2. Equatorial position
When a substitutent is present at axial position, the conformer will be less stable because it has 1, 3 diaxial interaction which is a steric interaction of axial group. This will increase the energy of the conformer and make it less stable.
When a substituent is present at equatorial position, the conformer is stable because the substituent has more room and fewer steric interactions when it is in an equatorial position.
For given trans-1, 4 dimethyl cyclohexane compound, the stable conformer will be the one which has both the methyl substituents at equatorial position.
Thus, conformer in option (c) is the correct one.