Sulfuric Acid → Clopidogrel Bisulfate

Participants

Reaction Steps

To a solution of Clopidogrel free base (13 g, 0.04 moles) in acetone (85 ml) at 25-30° C. was added dropwise dilute aqueous sulfuric acid (3.56 g, 0.036 mole). The solution was stirred for 15 minutes, distilled at 50-55° C. under reduced pressure (5-10 mm). Dichloromethane (130 ml) was added and distilled, the operation was repeated using dichloromethane (130 ml). Finally traces of water was removed under reduced pressure (5-10 mm) to give amorphous clopidogrel hydrogen sulfate (16.4 g). The amorphous form was similarly characterized by XRD, DSC, IR, chemical purity (HPLC)>99% and chiral purity (chiral HPLC) 99.4% (e.e.), % water 3.37, m.p. 128-130° C. (softens).

Provenance & Evidence