88-13-1

100523-84-0

(d) Synthesis of 5-bromo-3-thiophenecarboxylic acid: a glacial acetic acid solution of bromine was prepared by dissolving 16 g of Br2 (0.1 mol) in 200 ml of glacial acetic acid. This solution was slowly added dropwise to 100 ml of glacial acetic acid solution containing 3-thiophenecarboxylic acid (12.8 g; 0.1 mol). The reaction mixture was stirred at room temperature for 20 minutes. Upon completion of the reaction, the mixture was poured into a vessel containing water and ice to quench the reaction and promote precipitation of the product. The resulting white precipitate was collected by filtration and washed with water to remove residual glacial acetic acid. Finally, the product was purified by recrystallization from water to give 5-bromo-3-thiophenecarboxylic acid in 70% yield.