Hydrogen Peroxide → 4-Bromo-2-thiophenecarboxylic Acid

Participants

Reaction Steps

To a flask equipped with a mechanical stirrer was added 25 g (130 mmol) 4-bromothiophene-2-carbaldehyde (Aldrich Chemical Company), acetonitrile (200 mL), and 4.5 g (37.5 mmol) of sodium dihydrogen phosphate dissolved in 35 mL of water. After cooling this mixture on an ice-salt bath, 15 mL (169 mmol) of 35% hydrogen peroxide and 15.3 g (169 mmol) of sodium chlorite were added, and the mixture was stirred for 1 h. The reaction mixture was then stirred at room temperature for 3 h. The solvent was removed in vacuo, and the solid was suspended in a mixture of water (175 mL) and 1 N hydrochloric acid (4 mL) and stirred for 10 min at rt. The solid was collected on a Büchner funnel and washed with water (2×150 mL) to afford 26 g (97%) of 4-bromothiophene-2-carboxylic acid, which was used in the next step without further purification.

Provenance & Evidence