Concentrated hydrochloric acid was slowly added to a stirred solution of 4-fluoro-3-(trifluoromethyl)benzoic acid (10.0 g, 48.1 mmol) in methanol (100 mL). Subsequently, sulfuric acid (4 mL, 73.4 mmol) was added dropwise at room temperature and the reaction mixture was heated to reflux for 5 hours. Upon completion of the reaction, 200 mL of aqueous sodium bicarbonate was added to neutralize the reaction mixture, which was then extracted with ethyl acetate (100 mL × 3). The organic phases were combined, washed with saturated saline (100 mL × 2), dried over anhydrous sodium sulfate, and concentrated under reduced pressure to afford the title compound methyl 4-fluoro-3-trifluoromethylbenzoate (9.4 g, 88% yield) as a light yellow oil.1H NMR (400 MHz, CDCl3) δ 8.33 (dd, J = 6.8, 1.6 Hz, 1H), 8.28- 8.22 (m, 1H), 7.28 (t, 1H), 3.95 (s, 3H).
