General procedure for the synthesis of 3-methyl-4-nitroaniline (20-2) from 3-methyl-4-nitrobenzamide (20-1, 40 g, 222 mmol): 20-1 was dissolved in 400 mL of methanol/water (v/v=1/1) mixed solvent and cooled to 0 °C. Subsequently, sodium hydroxide (35.6 g, 888 mmol) was added to the solution and stirred for 0.5 hours. Sodium hypochlorite solution (380 g, 556 mmol) was added slowly and dropwise at 0°C. The reaction mixture was gradually warmed up to room temperature (20°C) and stirring was continued for 18 hours. After that, the mixture was further warmed up to 35°C and stirred for 1 hour, then warmed up to 75°C and stirred for 0.5 hours. After completion of the reaction, the mixture was cooled to room temperature. The pH was adjusted to 6.0 with hydrochloric acid, at which time a brown precipitate was produced. The precipitate was collected by filtration and washed twice with 200 mL of water to give the final 20-2 (29 g, 86% yield) as a tan powder.
