The general procedure for the synthesis of 2-amino-4-methylbenzamide using 2-amino-4-methylbenzonitrile as starting material was as follows: to a suspension of 2-amino-4-methylbenzonitrile (800 mg, 6.1 mmol) in water (1 mL), concentrated sulfuric acid (3 mL) was slowly added. The mixed solution was placed in an oil bath preheated to 120 °C and the reaction was stirred for 20 min. Immediately after completion of the reaction, the reaction mixture was cooled in an ice bath. Subsequently, the reaction solution was adjusted to alkaline by dropwise addition of 5% sodium hydroxide solution and the precipitated solid was collected by vacuum filtration. Finally, 484.4 mg of 2-amino-4-methylbenzamide was obtained in 53% yield as a light brown solid. The product was characterized by 1H NMR (DMSO-d6): δ 7.63 (br s, 1H), 7.42 (d, 1H), 6.95 (br s, 1H), 6.55 (br s, 2H), 6.45-6.48 (m, 1H), 6.29 (ddd, 1H), 2.16 (s, 3H). The mass spectrum (ES) showed a m/z of 134 (M-16).
