3-Amino-4-(propylamino)benzoic acid → 2-Methyl-1-propyl-1,3-benzodiazole-5-carboxylic acid

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Reaction Steps

A mixture of 4.5 parts of 3-amino-4-(propylamino)benzoic acid, 2.6 parts of ethyl ethanecarboximidate hydrochloride and 50 parts of acetic acid is stirred first for 20 minutes at room temperature and further for 10 minutes at reflux. The reaction mixture is evaporated. The residue is crystallized from 2-propanol. The product is filtered off, washed with water and 2-propanol and dried, yielding 1.8 parts of 2-methyl-1-propyl-1H-benzimidazole-5-carboxylic acid; mp. >260° C.

Provenance & Evidence