O-Phenylenediamine → 2-Pentyl-1H-benzimidazole

Participants

Reaction Steps

To a solution of 0-phenylenediamine (2.2 g) and triethylamine (2.0 g) in methylene chloride (20 ml) was added dropwise caproyl chloride (2.3 g) with stirring under ice-cooling. The mixture was stirred for 3 hours at room temperature, washed with a saturated aqueous sodium bicarbonate and water, then dried. The solvent was evaporated. To the residue was added 3N-HCl, and the mixture was heated for 1.5 hour under reflux. The reaction mixture was made basic with 6N NaOH. Then precipitating crystals were recrystallized from ethyl acetate-hexane to give colorless needles (1.5 g, 47%), m.p. 161°-162° C.

Provenance & Evidence