What are two conformations of cis-1,4-dimethyl cyclohexane?

1 Answer
Feb 7, 2017

I think there is only the one conformation of #"cis-dimethylcyclohexane."#



The upper trace shows the cis-isomer; i.e. one methyl is axial, and one methyl is equatorial. I think, quite clearly, the 2 conformers are superposable, and are therefore identical. On the other hand, for the trans isomer, in which the methyl groups are on opposite sides the ring, #"trans-diaxial"# is distinct from #"trans-diequatorial"#. Clearly the latter conformer would be most stable.

If you can't see the equivalence of the cis isomers, try using a set of molecular models, which are always allowed in examinations.