Step A: 3,4-dibromotoluene (108.11 mL, 800 mmol) was slowly added dropwise to 90% nitric acid (280 mL, 6000 mmol) pre-cooled to 0°C under nitrogen protection over a controlled period of 4 hours. The reaction mixture was mechanically stirred at 0°C to ensure that the internal temperature was always below 10°C. After the dropwise addition, stirring was continued at 0°C for 1 hour. Subsequently, water (840 mL) was added slowly, keeping the internal temperature below 10°C. The crude product was collected by filtration and washed thoroughly with water (5 x 500 mL) to remove residual nitric acid. The resulting solid was dried under high vacuum and then purified by recrystallization from ethanol (800 mL) to give 180.9 g (77% yield) of the target product 1,2-dibromo-4-methyl-5-nitrobenzene as a solid. The product was characterized by 1H NMR (400 MHz, CDCl3): δ 8.24 (s, 1H), 7.64 (s, 1H), 2.55 (s, 3H).
