Advices For Studying Organic Chemistry

a pair of enantiomers.

i) They are not superposable on each other.

ii) They are noninterconvertible by a ring-flip.

H

H 3 C CH 3

CH 3

CH 3

CH 3

H 3 C

No symmetry plane

H

H

H

(a) (b) (c)

Figure 5.19 trans-1,3-Dimethylcyclohexane does not have a plane of symmetry and
exists as a pair of enantiomers. The two structures (a and b) shown
here are not superposable as they stand, and flipping the ring of either
structure does not make it superposable on the other. (c) A simplified
representation of (b).

Symmetry

Top view plane

Chair view same as

Meso cis-1,3-dimethylcyclohexane

Mirrorplane

H 3 C

CH 3

CH 3

H 3 C

CH 3

H 3 C

CH 3

CH 3

Symmetry

plane