Question

Are enantiomers chiral and diastereomers achiral?

Answer 1

Enantiomers are always chiral, but diastereomers may or may not be chiral.

Explanation:

Diastereomers are optical isomers that are not mirror images of each other.

Here are the Fischer projections of some diastereomeric pairs.

Both diastereomers chiral

(+)-Erythrose and (-)-erythrose are enantiomers, as are (+)-threose and (-)-threose.

Each erythrose isomer is a diastereomer of each threose isomer, and each is chiral.

One chiral and one achiral diastereomer

Tartaric acid exists as a meso compound and a pair of enantiomers.

(from www.kshitij-iitjee.com)

Each of the enantiomers is a diastereomer of the achiral meso compound.

Both diastereomers achiral

2,3,4-Tribromopentane has three chiral carbons, but two of the eight possible stereoisomers are meso compounds because they have an internal plane of symmetry.

They are both achiral, but they are still diastereomers of each other.