What are optical isomers? Give me an example

1 Answer
May 4, 2015

Optical isomers are compounds that are nonsuperimposable mirror images of each other.

Isomers are molecules that have the same molecular formula but a different arrangement of atoms in space.

If the arrangement in space makes the two isomers nonsuperimposable mirror images of each other, we call them optical isomers or enantiomers.

An example is the amino acid alanine.


The solid bonds are in the plane of the paper.

The wedged bond means that the CH₃ group is in front of the paper, and the dashed bond means that the NH₂ is behind the paper.

No matter how hard you try, you can't make the two molecules superimposable.

You can't slide one molecule over the other so that all four groups coincide.


Two groups will always mismatch.

Alanine therefore exists as a pair of optical isomers. They are called D-alanine and L-alanine.