Bromine → 4-Bromo-5-chlorothiophene-2-carboxylic acid

Participants

Reaction Steps

A solution of bromine (634 uL, 12.3 mmol) in AcOH (2.5 mL) was added dropwise to 5-chloro-2-thiophenecarboxylic acid (2 g, 12.3 mmol) and FeCl3 (399 mg, 2.50 mmol) in AcOH (25 mL) at 25° C. The reaction mixture was warmed to reflux where additional bromine (634 uL, 12.3 mmol) and FeCl3 (399 mg, 2.50 mmol) were added. After 7 d, the solution was poured onto ice and the precipitate was filtered and washed with water affording the title compound (3 g, quant.) as a yellow powder: LCMS (ES) m/z 242 (M+H)+.

Provenance & Evidence