Question

A molecule is achiral if it has a plane of symmetry in any conformation. Each of the following conformations does not have a plane of symmetry, but rotation around a carbon–carbon bond forms a conformation that does have a plane of symmetry. Draw this conformation for each molecule.

a.

b.

Short answer

a.

b.

Step-by-step solution

Plane of symmetry

The term "plane of symmetry" refers to an imaginary plane that divides a molecule into two equal/identical halves.

Achiral molecules

The molecules that are superimposable with their corresponding mirror images are termed achiral.

Achiral molecules possess a plane of symmetry.

Rotation around carbon-carbon bonds

a. A rotation around the carbon-carbon bond ( and ) yields a conformer of the molecule that has a plane of symmetry.

Conformer of a

b. The rotation about the carbon-carbon ( and ) bond by yields the conformer that possesses a plane of symmetry.

Conformer of b