Which statements about cis-1,3-dimethylcyclohexane are correct?

AIn the (a,a) chair the two methyl groups point to opposite faces of the ring
BIts two chair conformers are (e,e) and (a,a)
CThe compound is chiral
DThe (e,e) chair is much more stable than the (a,a) chair

Answer: B, D

In 1,3-disubstituted cyclohexane, cis means (e,e) or (a,a). The diaxial chair carries a severe syn-diaxial CH

_{3}

/CH

_{3}

interaction, so the (e,e) chair predominates. The compound is meso (mirror plane through C2 and C5), and cis means both methyls are on the same face, so the last two statements are false.

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