Sulfuric Acid → Clopidogrel Bisulfate

Participants

Reaction Steps

Clopidogrel base (2.98 g) was dissolved in 2-butanol (23 mL). Ninety eight percent aqueous sulfuric acid (0.50 mL) was added to the solution at 20° C. The reaction mixture was heated to reflux temperature for 2 hours. The solution was cooled to room temperature and stirred at this temperature for an additional 3 hours. Then the solvent was evaporated to dryness under reduced pressure to obtain an oil. Then tert-butyl methyl ether (MTBE) (44 mL) was added to the oily residue and the resulting mixture was stirred at room temperature for 16 hours. The precipitate was collected by filtration, washed with MTBE (2×10 ml) and dried at 50° C. in a vacuum oven for 22.5 hours to obtain 3.38 g (87%) of clopidogrel hydrogensulfate crystal Form V.

Provenance & Evidence