Patent ID: 7629465
Filing Date: 2009-12-08
Classification: C07D

Abstract:
1. An process for making Form I crystals of (+)-(S)-clopidogrel hydrogen sulphate of Formula IB comprising the steps of: i) dissolving methyl (+)-(S)-α-(2-chlorophenyl)-4,5,6,7-tetrahydrothieno [3,2-C]pyridine-5-acetate ((+)-(S)-clopidogrel base) in a solvent selected from methyl propyl ketone, methyl isopropyl ketone, diethyl ketone, mixture of ketone solvents, ethyl acetate—methyl propyl ketone mixture, ethyl acetate-methyl isopropyl ketone mixture, and ethyl acetate-diethyl ketone mixture; ii) cooling said clopidogrel base solution; iii) adding sulphuric acid to said cooled solution to form a salt mixture; iv) maintaining said salt mixture to precipitate (+)-(S)-clopidogrel hydrogen sulphate in Form I; and v) recovering said crystals of Form I.