Phosphorus oxide (P4O10) → 5,6-Dichloro-2-(4-cyano-2-ethoxyphenyl)benzimidazole hydrochloride

Participants

Reaction Steps

A suspension of N-(2-amino-4,5-dichlorophenyl)-2-ethoxy-4-cyanobenzamide (19 g, 54.2 mmol) and P2O5 (19 g, 134 mmol) in xylene (380 ml) was refluxed for 24 h. Additional P2O5 (9.5 g, 67 mmol) was added and the mixture was refluxed for 48 h. Solvent was removed under reduced pressure. The residue was treated with 30% NaOH (80 ml) and water (100 ml) and then acidified with 37% HCl. The solid was filtered, washed with water and dried under vacuum at 50° C. to give 16.5 g of the title compound as a light brown powder (yield 82.6%), mp>250° C.

Provenance & Evidence