General procedure for the synthesis of 4-(cyanomethyl)benzoic acid from methyl 4-(cyanomethyl)benzoate: Methyl 4-(cyanomethyl)benzoate (25 g, 0.14 mol) was dissolved in 300 mL of methanol, followed by the addition of 160 mL of a 1N NaOH solution, and the reaction was carried out at reflux for 3 hours. Upon completion of the reaction, most of the solvent was evaporated under reduced pressure. To the residue, 500 mL of water was added and the pH was adjusted to 2-3 with concentrated hydrochloric acid.The precipitated solid was filtered, washed with water and dried to give 4-(cyanomethyl)benzoic acid (21.2 g, 92.2% yield) as a white solid. The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ 12.89 (brs, 1H), 7.87 (d, J=8.2 Hz, 2H), 7.37 (d, J=8.2 Hz, 2H), 3.45 (s, 2H); MS (EI): 161 [M]+.
