Phthaloyl chloride → 2-(1H-benzimidazol-2-yl)isoindole-1,3-dione

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Reaction Steps

2-Aminobenzimidazole (13.3 g.) is dissolved in 50 ml. of pyridine, and 10.2 g. of phthaloyl chloride is added, causing immediate precipitation. On mixing and heating on the steam-bath, all dissolves. The solution is heated 2 hours on the steam-bath with occasional swirling. It is cooled to room temperature and quenched in 200 ml. of water. After 1 hour agitation, the mixture is filtered free of solids and the solids washed with water. The yield of N-(benzimidazol-2-yl)phthalimide is 11.6 g. Recrystallization from glacial acetic acid results in bright yellow crystals of N-(benzimidazol-2-yl)phthalimide which, after drying, melts at 266°-268° C., λmax. 295.0, E11%cm. 529.

Provenance & Evidence