A mixed solution of 2-bromo-3-methylbenzoic acid (5 g, 23.2 mmol) and concentrated sulfuric acid (0.5 mL) in anhydrous methanol (100 mL) was heated to reflux for 20 hours. Upon completion of the reaction, the solvent was removed by concentration under reduced pressure by rotary evaporator. The concentrated residue was dissolved in dichloromethane (50 mL) and washed with saturated sodium bicarbonate solution (30 mL) to neutralize the acid. The organic phase was dried over anhydrous sodium sulfate, filtered and concentrated again under reduced pressure by rotary evaporator to afford methyl 2-bromo-3-methylbenzoate (4.43 g, 19.3 mmol, 83% yield). The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 2.46 (s, 3H), 3.93 (s, 3H), 7.24 (t, J = 8.0 Hz, 1H), 7.34 (dd, J = 1.0 Hz, J = 8.0 Hz, 1H), 7.46 (dd, J = 1.0 Hz, J = 8.0 Hz, 1H).
