4-Fluoro-3-nitrobenzenesulfonamide

1493-27-2

406233-31-6

General procedure for the synthesis of 4-fluoro-3-nitrobenzenesulfonamide from 1-fluoro-2-nitrobenzene: 1-fluoro-2-nitrobenzene (4.0 g, 28.4 mmol) was dissolved in chlorosulfonic acid (25 mL), and the reaction was stirred at 120°C overnight. Upon completion of the reaction, it was cooled to room temperature and quenched by slow pouring into ice water. The reaction mixture was extracted with ethyl acetate (50 mL x 3), the organic layers were combined and concentrated under reduced pressure to remove the solvent. The crude product was redissolved in isopropanol and cooled to -60°C. At this temperature, ammonium hydroxide solution was added dropwise and stirring was continued for 1 hour. Subsequently, 6M hydrochloric acid (8 mL) was added to neutralize the reaction and the reaction mixture was warmed to room temperature and concentrated to dryness. The intermediate 4-fluoro-3-nitrobenzenesulfonamide (5.1 g, 82% yield) was finally obtained as a white solid.1H NMR (400 MHz, DMSO-d6) δ: 8.52 (dd, 1H), 8.20 (dq, 1H), 7.84 (dt, 1H), 7.73 (s, 2H).