[Synthesis]
General procedure for the synthesis of 2,3-dimethyl-6-nitroaniline and 2,3-dimethyl-4-nitroaniline from the compounds (CAS:114166-32-4) and N-(2,3-dimethyl-6-nitrophenyl)acetamide: To a solution of N-(2,3-dimethyl-6-nitrophenyl)acetamide (16.0 g, 1.0 equiv.) was added a 60% H2SO4 solution (150 mL). The reaction mixture was heated to reflux temperature, maintained for 1 hour and then cooled to room temperature. The solution was diluted with ice water (100 mL) and neutralized with 2N NaOH solution. The reaction mixture was extracted with EtOAc (3 x 50 mL). The organic phases were combined, washed sequentially with saturated NaHCO3 solution (2 × 50 mL) and saturated NaCl solution (2 × 50 mL), dried over anhydrous Na2SO4 and concentrated under reduced pressure. The residue was purified by column chromatography (10% CH2Cl2/hexane) to afford 2,3-dimethyl-6-nitroaniline (5.5 g, 43%) and 2,3-dimethyl-4-nitroaniline (1.5 g, 12%).
1H NMR data for 2,3-dimethyl-6-nitroaniline (5.5 g, 43%): δ 2.05 (s, 3H), 2.20 (s, 3H), 6.15 (br s, 2H), 6.45 (d, J=8.7 Hz, 1H), 7.63 (d, J=9.0 Hz, 1H) in CDCl3; δ 2.10 (s 3H), 2.30 (s, 3H), 6.50 (d, J=8.7Hz, 1H), 7.15 (br s, 2H), 7.75 (d, J=9.0Hz, 1H).
1H NMR data for 2,3-dimethyl-4-nitroaniline: δ 2.10 (s, 3H), 2.45 (s, 3H), 4.05 (br s, 2H), 6.45 (d, J=9.0 Hz, 1H), 7.65 (d, J=8.7 Hz, 1H) in CDCl3; δ 2.00 (s, 3H), 2.35 (s 3H), 6.12 (br s, 2H), 6.53 (d, J=9.0 Hz, 1H), 7.63 (d, J=9.0 Hz, 1H). |