3-Chloro-5-fluorobenzyl bromide (58.23 g, 260 mmol) and acetic acid (5.35 mL, 93.6 mmol) were dissolved in toluene (260 mL). Aqueous sodium cyanide (195 mL, 48.57 g, 990 mmol) and tributylbenzyl ammonium chloride (5.68 g, 18.2 mmol) were added slowly and dropwise with stirring. The reaction mixture was stirred continuously at room temperature for 4 hours. After completion of the reaction, the organic layer was separated and washed sequentially with deionized water (200 mL) and saturated sodium chloride solution (200 mL). The organic layer was dried over anhydrous magnesium sulfate and concentrated under reduced pressure to remove the solvent. The crude product obtained was purified by basic silica gel column chromatography using hexane-ethyl acetate (4:1, v/v) as eluent to give 3-chloro-5-fluorophenylacetonitrile (44.89 g, 100% yield) as a brown oil. The structure of the product was confirmed by 1H NMR (300 MHz, CDCl3): δ 3.74 (2H, s), 6.99 (1H, d, J = 8.7 Hz), 7.05-7.13 (1H, m), 7.15 (1H, s).
