Process for crystallizing enantiomerically enriched 2-acetylthio-3-phenylpropionic acid

Abstract

Process for crystallizing 2-acetylthio-3-phenylpropionic acid from a solution of acetylthiophenylpropionic acid, wherein, at a temperature lower than 50° C., an antisolvent is added to form a mixture of antisolvent and acetylthiophenylpropionic acid solution; wherein seed crystals are added to the mixture before crystallisation occurs; and wherein the antisolvent is dosed over time during the occurrence of crystallisation. Preferably, the crude reaction mixture obtained in the preparation of the acetylthiophenylpropionic acid is applied as acetylthiophenylpropionic acid-containing medium. Preferably the seed crystals are added while the mixture is in the metastable phase range. Free flowing acetylthiophenyl propionic acid particles are obtained. The invention also relates to such particles.

Dependencies are inferred from the claim text.