3-Bromobenzoic acid (249 g, 1.24 mol, 1.0 eq.) was suspended in concentrated sulfuric acid (800 mL), and the suspension was cooled to 0 °C. The solution was then mixed with nitric acid (57.2 mL, 1.2 mol). Nitric acid (57.1 mL, 1.2 mol) was slowly added dropwise with stirring. After the dropwise addition was completed, the reaction mixture was gradually warmed to 20 °C and stirring was continued for 1 hour. After completion of the reaction, the mixture was carefully poured into ice water (2 L). The precipitate precipitated was collected by filtration, washed sequentially with water (1000 mL x 2) and dried to give 5-bromo-2-nitrobenzoic acid (280 g, 1.14 mol, 91.94% yield) as a white solid. The product was characterized by 1H NMR (400 MHz, DMSO-d6): δ= 14.12 (br.s, 1H), 8.00 (d, J = 1.8 Hz, 1H), 7.98-7.90 (m, 2H).
