Thiophene-3-carboxylic acid → 5-Bromothiophene-3-carboxylic acid

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Reaction Steps

Thiophene-3-formic acid (12.5 g), AcOH (83 ml) are added to a reaction flask (500 ml), stirred at room temperature and dissolved to obtain a colorless transparent liquid. A solution of Br2 (5.4 ml) in AcOH (100 ml) is placed in a constant pressure funnel and dropped to the reaction flask at room temperature and kept at a temperature below 25° C. After addition, the reaction is carried out at room temperature overnight. The reaction mixture is poured into ice-water next day, stirred for about 30 minutes, filtered to form a white powder solid. The white powder solid is crystallized with hot water, filtered and dried to obtain a white crystal of 5-bromo-thiophene-3-formic acid (10 g), content of 92% measured by HPLC.

Provenance & Evidence