General procedure for the synthesis of 2-fluoro-6-nitroaniline from N-(2-fluoro-6-nitrophenyl)acetamide: 3 g (0.0151 mol) of N-(2-fluoro-6-nitrophenyl)acetamide (3a) was dissolved in 30 mL of concentrated H2SO4 and the reaction was stirred for 2 hr at 50 °C. After completion of the reaction, it was cooled to room temperature and the reaction solution was slowly poured into an ice bath and a large amount of precipitate was observed to be generated. The precipitate was collected by filtration and the acidic aqueous solution was extracted with ether. Purification by fast column chromatography afforded the target compound 2-fluoro-6-nitroaniline in 74% yield. The melting point of the product was 47-48 °C. 1H NMR (DMSO-d6) data: δ 7.82 (d, 1H, J=8.8 Hz, H-5), 7.42 (m, 1H, H-3), 7.25 (s, 2H, NH2), 6.63 (m, 1H, H-4). GC/MS analysis showed the molecular ion peak as 157 (M+H). Elemental analysis (C6H5FN2O2) Calculated values: C, 46.16; H, 3.23; F, 12.17; N, 17.94. Measured values: C, 46.18; H, 3.27; F, 12.15; N, 17.98.
