Nitric acid (24 mL, 0.55 mol) was slowly added dropwise to a solution of 2-hydroxy-3-(trifluoromethyl)pyridine (20.00 g, 0.12 mol) in 160 mL of sulfuric acid at -10 °C, and the reaction mixture was stirred at 40 °C for 6 hours. The progress of the reaction was then confirmed by TLC. After the reaction was complete, the reaction mixture was added to ice water, and the pH of the solution was adjusted to 4-5 with saturated NaOH aqueous solution. The aqueous layer was extracted with ethyl acetate, and the resulting organic layer was washed with saturated brine, dried over anhydrous sodium sulfate, filtered, and concentrated under reduced pressure to obtain 2-hydroxy-5-nitro-3-trifluoromethylpyridine.
