Formic Acid → 1,6-Dimethyl-1H-benzimidazole

Participants

Reaction Steps

A mixture of 6.60 g of 1-amino-4-methyl-2-(N-methylamino)benzene and a solution of 3.5 ml of formic acid in 50 ml of a 4N HCl was stirred at 100° C. for 3.5 hours. The reaction solution was concentrated under reduced pressure and water was added to the residue. After washing with ethyl acetate, the aqueous phase was rendered alkaline with aqueous potassium carbonate followed by extraction with chloroform. The chloroform layer was washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography (40 g). Elution with ethyl acetate followed by recyrstallization from ethyl acetate-hexane gave 4.01 g (57%) of 1,6-dimethylbenzimidazole.

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