The Stability of the Supersaturation State in Optical Resolution by the Preferential Crystallization Procedure

Abstract

Abstract In the optical resolution process of Dl-serine m-xylene-4-sulfonate dihydrate by the preferential crystallization procedure, the stability of the supersaturation state of the unseeded isomer was investigated in connection with the cooling conditions. The experiment was initiated with the model solution and was then extended to the actual resolution process. The metastable region of the unseeded isomer on a two-dimensional diagram with the supersaturation degree and cooling time could be divided into the first and the second metastable regions. The limits of the first and the second metastable regions were expressed by a supersaturation degree and by an area on the diagram respectively. Both limiting values were constant, independent of cooling speed and the lowest arrival temperature, if the conditions for the crystallizer, the initial concentration of the Dl-form, the amount of the seed crystals, and the degree of stirring were fixed.