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.