The general procedure for the synthesis of 4-bromo-2-trifluoromethylphenylacetonitrile from 5-bromo-2-methyltrifluorotoluene and potassium cyanide was as follows: 4-methyl-3-trifluorobromobenzene (33.26 g, 104.261 mmol), potassium cyanide (20.43 g, 313.67 mmol) and tetrabutylammonium bromide (3.37 g, 10.45 mmol) were reacted in a methylene chloride/water (1:1, 300 mL) in a solvent mixture of dichloromethane/water, and the reaction was stirred at room temperature for 4 hours. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water (100 mL), 1N hydrochloric acid (100 mL), and saturated saline, and dried over anhydrous sodium sulfate. The organic layer was concentrated under reduced pressure to obtain a brown oily crude product. The crude product was purified by fast column chromatography (eluent: 0% to 20% hexane solution of ethyl acetate) to afford the target product 4-bromo-2-trifluoromethylphenylacetonitrile (14.9 g, 54% yield) in the form of a colorless transparent oil. The structure of the product was confirmed by 1H NMR (400 MHz, CDCl3): δ 3.91 (s, 2H), 7.57 (d, J = 8.3 Hz, 1H), 7.75 (dd, J = 8.3, 2Hz, 1H), 7.84 (d, J = 2Hz, 1H).
