2-Bromo-4-fluoro-5-methylbenzaldehyde (purchased from 3B Scientific Corporation, 1840 Industrial Drive, Suite 160, Libertyville, IL 60048, USA; 1.0 g, 4.61 mmol) was used as a raw material, which was mixed with sulfamic acid (2.68 g 27.65 mmol), sodium chlorite (539 mg, 6 mmol) and KH2PO4 (7.52 g, 55.3 mmol) in a 50% aqueous dioxane solution (96 mL). The reaction mixture was stirred overnight at room temperature. After the reaction was completed, the mixture was concentrated and diluted with water (20 mL). The resulting mixture was extracted with ethyl acetate (3 x 250 mL). The organic layers were combined, dried over anhydrous sodium sulfate, filtered and the solvent evaporated to give 2-bromo-4-fluoro-5-methylbenzoic acid (1.0 g, 93% yield) as an off-white solid. Mass spectrometry analysis: calculated value C8H6BrFO2 [M-H] 231, measured value 231.0.
