Temperature Cycling Induced Deracemization of NaClO₃ under the Influence of Na₂S₂O₆

Sodium chlorate (NaClO3) is an achiral compound forming a chiral crystal in the solid state. It is historically the model compound used by Viedma to report his discovery of the symmetry breaking phenomenon now called Viedma ripening. In this paper, a temperature cycling induced deracemization (TCID) process—recently described as particularly efficient for organic compound deracemization—was developed for NaClO3, and the results were compared to the well-known Viedma ripening process. While the presence of chiral impurities usually improves the efficacy of chiral compounds TCID, we observed that the voluntary addition of an inorganic impurity (sodium dithionate, Na2S2O6) had an opposite effect on the TCID process of NaClO3. Indeed, the process was strongly delayed by the presence of Na2S2O6. This phenomenon was explained by a suitable combination of crystal growth rate and secondary nucleation rate evaluations.