Chiral Symmetry Breaking in Sodium Chlorate Crystallization

Sodium chlorate (NaClO 3 ) crystals are optically active although the molecules of the compound are not chiral. When crystallized from an aqueous solution while the solution is not stirred, statistically equal numbers of levo (L) and dextro (D) NaClO 3 crystals were found. When the solution was stirred, however, almost all of the NaClO 3 crystals (99.7 percent) in a particular sample had the same chirality, either levo or dextro. This result represents an experimental demonstration of chiral symmetry breaking or total spontaneous resolution on a macroscopic level brought about by autocatalysis and competition between L- and D-crystals.