Phosphorus oxychloride → Methyl 2-chloro-1H-benzo[d]imidazole-5-carboxylate

Participants

Reaction Steps

Methyl 2-oxo-2,3-dihydro-1H-benzimidazole-6-carboxylate (43 g, 0.22 mol) was charged into phosphorus oxychloride (286 ml). Dry hydrogen chloride was bubbled through the boiling reaction mass for 12 hours. After cooling a reaction mass was poured into a mixture of ice and water (2 kg). Precipitate was filtered out. Filtrate was diluted with water (1.25 1) and ammonia solution (˜800 ml), after that pH was adjusted to 5.6 with ammonia solution. Precipitate was filtered and rinsed with water. Yield was 39.5 g (84%).

Provenance & Evidence