To a solution of 4,4'-diaminodiphenylmethane (50 mg, 0.25 mmol), pyridine (47 mg, 0.60 mmol) and 4-(dimethylamino)pyridine (1 mg) in dichloromethane (2.5 mL) was added acetic anhydride (56 mg, 0.55 mmol). The reaction mixture was stirred at 0 °C and gradually warmed to 25 °C for 12 hours. Upon completion of the reaction, the mixture was poured into water (10 mL) and extracted with ethyl acetate (50 mL x 2). The organic layers were combined, dried over anhydrous sodium sulfate, filtered and concentrated under reduced pressure. To the residue was added ether (10 mL) and the resulting precipitate was collected by filtration to give N,N'-diacetamidodiphenylmethane (59 mg, 0.21 mmol, 84% yield) as a colorless solid. Melting point: 224-225°C (decomposition).1H NMR (DMSO-d6): δ2.02 (s, 6H), 3.80 (s, 2H), 7.11 (d, J=8.2Hz, 4H), 7.48 (d, J=8.2Hz, 4H), 9.88 (br, 2H).13C NMR (DMSO-d6): δ24.2,40.2 ,119.3,129.0,136.3,137.5,168.3. IR (ATR): 1650 cm-1. MS (EI): m/z 282 (M+). Elemental analysis (C17H18N2O2) Calculated values: C, 72.32; H, 6.43; N, 9.92. Measured values: C, 72.21; H, 6.42; N, 9.91.
