In the lowest energy chair conformation of $\mathrm{methylcyclohexane}$, how many methyl groups are in the axial position?

• A. $0$
• B. $6$
• C. $1$
• D. $2$

Answer: (C)

Verified step by step guidance

1. Recall that in cyclohexane chair conformations, substituents can occupy either axial (parallel to the ring's axis) or equatorial (around the ring's equator) positions.
2. Understand that the lowest energy conformation of substituted cyclohexanes generally places bulky groups in the equatorial position to minimize steric strain and 1,3-diaxial interactions.
3. For methylcyclohexane, there is only one methyl substituent attached to the ring, so consider the two possible chair conformations: one with the methyl group axial and one with it equatorial.
4. Compare the energies of these two conformations; the equatorial methyl group is more stable because it avoids unfavorable 1,3-diaxial interactions, making the conformation with the methyl group equatorial the lowest energy form.
5. Therefore, in the lowest energy chair conformation of methylcyclohexane, the number of methyl groups in the axial position is one or zero? Since the methyl prefers equatorial, the answer is zero.