Methanol → 4-Bromo-2-thiophenecarboxylic Acid

Participants

Reaction Conditions

Reaction Steps

To a solution of chromium(VI)oxide (1.57 g, 15.70 mmol) in water (3 mL) was added dropwise concentrated sulfuric acid (1.3 mL, 23.55 mmol). The formed precipitate was re-dissolved by slow addition of the minimum required amount of water and the solution was cooled with an ice bath. This solution was then added dropwise to a solution of 4-bromo-2-thiophenecarboxaldehyde (2.0 g, 10.47 mmol) in acetone (20 mL) at about 5° C. The reaction mixture was stirred at about 5° C. for about 30 minutes and then at room temperature for about 2 hours. Methanol (30 mL) was added to the reaction mixture to destroy excess oxidant and the formed solids were collected by filtration. The filtrate was concentrated under vacuum and the residue was partitioned between diethyl ether and water. The organic extract was washed with water and brine, dried (MgSO4), filtered and concentrated under vacuum to provide the desired product. MS (DCI-NH3): m/z 206, 208 (M)+.

Provenance & Evidence