Phosphorus oxychloride → 2-Chlorobenzimidazole

Participants

Reaction Steps

A mixture of 2-hydroxybenzimidazole (300 g, 2.42 mol) and phosphorus oxychloride (1000 g) was heated at reflux temperature for 1 h to obtain a solution. Gaseous HCl was bubbled into the refluxing solution for 4 h and the solution then concentrated on a rotary evaporator. The residue was added to a mixture of aqueous potassium carbonate and methylene chloride and stirred for 18 h. The resulting mixture consisted of 2 liquid layers and a solid. The solid was collected and recrystallized from ethyl acetate and methanol.

Provenance & Evidence