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 7d, 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