Formaldehyde → 6-Chloro-1-ethyl-2-methyl-7-methylamino-5-trifluoromethylbenzimidazole

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Reaction Steps

To 1.0g. of 7-amino-6-chloro-1-ethyl-2-methyl-5-trifluoromethylbenzimidazole (Example IV) dissolved in 10 ml. of concentrated H2SO4 was added 1.0g. of paraformaldehyde. The resultant mixture was stirred at 80°C. for 2 hours and then poured onto ice. The resultant brown solution was made basic by addition of concentrated NH4OH, precipitating a light brown solid. The mixture was extracted with chloroform and the chloroform extracts washed with water and dried over Na2SO4. After removal of the chloroform by evaporation, the residue was extracted with hexane and the hexane extract distilled to dryness. The solid residue was recrystallized from hexane to give 0.77g. (73.3%) of the desired product, m.p. 116.5°-119°C.

Provenance & Evidence