1. Oxidation: 4-(Trifluoromethyl)benzaldehyde (1.54 g, 6.75 mmol, 1.0 eq.) and dichloromethane (20 mL) were added to a round-bottomed flask and m-chloroperoxybenzoic acid (mCPBA, 1.52 g, 6.78 mmol, 1.0 eq.) was added slowly at room temperature. The reaction mixture was stirred at room temperature for 2 hours. Upon completion of the reaction, the reaction was quenched by the addition of saturated aqueous sodium bisulfite solution (15 mL). The mixture was transferred to a partition funnel and extracted with dichloromethane. The organic phases were combined, dried with anhydrous sodium sulfate and concentrated under reduced pressure to give 4-(trifluoromethyl)phenol in 71% yield.
2. Chlorination reaction: N-chlorosuccinimide (NCS, 25.0 mmol, 3.4 g) and dichloromethane (20.0 mL) were added to another round-bottomed flask and cooled to -78 °C. The reaction was carried out by adding zirconium tetrachloride (ZrCl2) to the mixture. Zirconium tetrachloride (ZrCl4, 0.5 mmol, 300 mg) was added, followed by 4-(trifluoromethyl)phenol (25.0 mmol). The reaction mixture was warmed to room temperature and stirred for 6 hours. After completion of the reaction, it was extracted with saturated aqueous sodium bicarbonate. The organic phases were combined and the solvent was removed under reduced pressure to afford 2-chloro-4-(trifluoromethyl)phenol in 88% yield.
