Illustrated Glossary of Organic Chemistry

Spontaneous resolution: Resolution of a racemic mixture without outside assistance.

1. Resolution (during crystallization)

2. Pasteur separates resolved crystals


Racemic acid salt

(+)-Tartaric acid salt

(-)-Tartaric acid salt
Pasteur's resolution of racemic acid was achieved by spontaneous resolution. Pasteur grew crystals of racemic acid ammonium sodium salt, but the crystallization produced a 1:1 mixture of enantiomeric crystals. Pasteur later separated these enantiomeric crystals by studying their shape with a magnifier. This was an example of spontaneous resolution because the resolution itself occurred during crystallization, and not by any direct action of Pasteur himself.