The general procedure for the synthesis of 3-chloro-4-trifluoromethylbenzonitrile from 3-chloro-4-trifluoromethylbenzaldehyde was as follows: at 0 °C, using a syringe, diisobutylaluminum hydride (1.0 M toluene solution, 28 mL, 28 mmol) was added slowly and dropwise to 3-chloro-4-(trifluoromethyl)benzonitrile (3.79 g, 18.4 mmol) in tetrahydrofuran (THF, 50 mL ) solution. The reaction mixture was kept at 0 °C for 2 h, followed by warming to room temperature and continued stirring for 2 h. The reaction was carried out on a cooled surface. Upon completion of the reaction, the mixture was cooled to 0 °C and the reaction was quenched with 3M aqueous hydrochloric acid solution (75 mL). The mixture was warmed to room temperature and stirred vigorously for 1.5 hours. Subsequently, the mixture was transferred to a dispensing funnel and diluted with ether (Et2O). The organic phase was separated, dried over anhydrous sodium sulfate (Na2SO4), filtered and concentrated under reduced pressure. Purification by fast chromatography (Analogix? IntelliFlash 280? system, using 15% ethyl acetate/hexane as eluent, SF40-150g column) gave 2.84 g (74% yield) of 3-chloro-4-trifluoromethylbenzaldehyde as a colorless oil. The structure of the product was confirmed by 1H NMR (300 MHz, DMSO-d6): δ 10.09 (s, 1H), 8.21 (s, 1H), 8.12 (d, J = 8.1 Hz, 1H), 8.07-8.02 (m, 1H).
