Phosphorus oxychloride → 2-Chlorobenzimidazole

Participants

Reaction Steps

According to the procedure D. Harrison, et al., J. Chem. Soc., 2930, 1963, a mixture of 2-hydroxybenzimidazole (40.0 g, 0.298 mol) and phosphoryl chloride (400 mL) was heated under reflux for 3 hours, cooled, and concentrated. The resulting slurry was poured onto ice and the solid (starting material) was removed by filtration. The filtrate was adjusted to pH 6 with 30% aqueous NH3 and the resulting white precipitate was collected by filtration and dried to give 26.1 g (57%) of product m.p. 184°-186° C.

Provenance & Evidence