Short-RInChIKey=SA-FUHFF-UHFFFADPSC-IRELIHAAUC-UHFFFADPSC-NUHFF-NUHFF-NUHFF-ZZZ

In a round bottom flask to a stirred solution of 2-hydroxy-4-(trifluoromethyl)benzoic acid (3.00 g, 14.55 mmol, 1.00 equiv) in methanol (15.0 mL) was added concentrated sulfuric acid (0.910 mL,16.74 mmol, 1.15 equiv) dropwise at 25 °C. The reaction mixture was refluxed at 65 °C for 24 hours (TLC control: hexane/ethyl acetate 10:1). After completion of the reaction, the reaction mixture was cooled, poured into water (40 mL), and extracted with DCM three times (3 × 50 mL). The combined organic layers were washed with a saturated solution of NaHCO3 (50 mL) and two times with brine (2*50 mL), dried over anhydrous Na2SO4, and concentrated under reduced pressure to give the product methyl 2-hydroxy-4-(trifluoromethyl)benzoate (2.93 g, 91%) as a colourless oil. Product was used without any additional purification step.