Patent ID: 7396931

Claim:
Process for the preparation of the amorphous form of methyl (S)-(+)-(2-clolophenyl-2(6,7-dihydro-4H-thieno [3,2-c]pyridine-5-yl-acetate hydrogen-sulfate of the formula which comprises, dissolving clopidogrel base in a first solvent, adding sulfuric acid, adding the obtained mixture containing clopidogrel hydrogensulfate to a second solvent to obtain a precipitate, and filtering precipitate, wherein the first solvent and the second solvent are present in one of the following combinations selected from the group consisting of: combination (i) acetone and diisopropyl ether; combination (ii) dichloromethane and diisopropyl ether; combination (iii) dichloromethane and cyclohexane; and combination (iv) dichloromethane and ethyl acetate.