Pyridine → Nitazoxanide Impurity

Participants

Reaction Conditions

Reaction Steps

2-(Acetyloxy)-benzoic acid (500, 1.80 g, 10.0 mmol) was placed in a 250 mL round bottom flask equipped with a stirbar, vacuum adapter and septum. Ether (100 mL) and pyridine (1.00 mL, 12.4 mmol) were added to create a clear, colorless solution, which was cooled to zero in an ice bath before thionyl chloride (875 μL, 12.0 mmol) was added dropwise over ca. 30 sec. A thick white precipitate formed upon the addition of each drop. The reaction mixture was stirred for 90 minutes at 0° C. before being filtered through paper, and removing the solvents in vacuo. Sodium bicarbonate (3.42 g, 40.7 mmol) and 1,3-thiazol-2-amine (1.00 g, 10.0 mmol) were weighed into a 250 mL round bottom flask and water (30 mL) and ethyl acetate (30 mL) were added to form a colorless biphase, which was stirred rapidly. The crude acid chloride was suspended in ethyl acetate (10 mL) and added dropwise to the rapidly stirring biphase. The resulting biphase was capped lightly and stirred rapidly at room temperature for 2 hours. The biphase layers were separated, and the aqueous was extracted twice with ethyl acetate. The combined organics were washed with brine, dried with MgSO4, filtered, and concentrated to give 501 (1.36 g, 52%) as a colorless powder, which was used without purification.

Provenance & Evidence