Formic Acid → Ethyl 1H-benzimidazole-6-carboxylate

Participants

Reaction Steps

40 g of 3,4-diaminobenzoic acid ethyl ester (0.22 mol) and 200 mL formic acid were added to a three-necked bottle. After refluxing for 7 h, the reaction was completed. After concentration under reduced pressure, the ice water was poured into the residual solution. The resulting mixture was adjusted to pH 7 with sodium hydroxide. After sucking filtration, the filtrate was extracted with dichloromethane thrice, dried with anhydrous sodium sulfate, and decolored with active charcoal. Then the solution was concentrated under reduced pressure to get a white solid (29.6 g). Yield: 70.2%. MS: 191 (M+1)

Provenance & Evidence