Optical Resolution by Preferential Crystallization of DL-Thiazolidine-4-carboxylic Acid

Article abstract of DOI:10.1246/bcsj.60.3277

Infrared spectrum, solubility, and ternary solubility diagram indicated that DL-thiazolidine-4-carboxylic acid (DL-THC) is a conglomerate at room temperature.The free energy of critical nucleation in supersaturated solutions for the crystallization of D- and L-THC was examined to resolve DL-THC efficiently by preferential crystallization.Successive preferential crystallization of DL-THC was experimented at 20 deg C for an aqueous racemic solution with a supersaturation of 150percent, and D- and L-THC with optical purity 96-100percent were obtained in the range of resolution of 58-76percent.The optical resolution was more succesfully done in 1 mol dm^-3 aqueous glycine to give D- and L-THC with optical purity of 93-99percent in the degree of resolution of 77-87percent.Recrystallization of D- and L-THC obtained with a succeeding treatment with hydroxylamine hydrochloride gave D- and L-cysteine with 100percent optical purity.