Malononitrile (32 mmol) and acetophenone (28 mmol) were dissolved in 20 mL of toluene solution containing ammonium acetate (500 mg, 6.5 mmol) and glacial acetic acid (2 mL) in a 50 mL round bottom flask. The water generated during the reaction was removed by vigorous reflux using a Dean-Stark water separator mounted under the reflux condenser. Upon completion of the reaction, the toluene was removed by evaporation to give the crude product. The crude product was further purified by recrystallization from ethanol or vacuum distillation to afford the target compound 2-(1-phenylethylidene)malononitrile in 61% yield. The structure of the product was confirmed by 1H NMR (CDCl3, 300 MHz) and 13C NMR (CDCl3, 75 MHz): 1H NMR δ 7.56-7.50 (m, 5H, ArH), 2.63 (s, 3H); 13C NMR δ 175.4, 135.7, 132.1, 128.9, 127.2, 112.7, 112.6, 84.5, 24.1.
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