2-Methyl-6-nitroaniline

120-66-1

570-24-1

The general procedure for the synthesis of 2-methyl-6-nitroaniline from 2-methylacetanilide was carried out as follows: the modified Howard method [27] was used. Toluidine (1a or 1b; 53.5 mL, 0.5 mol) was slowly added to acetic anhydride (325 mL) in batches while maintaining constant stirring. The reaction solution was cooled to 12-13 °C in an ice-salt bath. Subsequently, 70% nitric acid (63 mL) was slowly added dropwise to the reaction mixture at a rate that maintained the temperature at 10-12 °C with constant stirring. The dropwise addition process took 2.5 h to complete, after which the solution was poured into 1.5 L of ice water. The resulting acetamide (3a, or a mixture of 3b and 3c) precipitate (as a cream-colored solid) was collected on a Brinell's funnel, washed with four 250 mL portions of ice water, and partially dried by suction. The wetted acetamide (3a, or a mixture of 3b and 3c) was mixed with 70% sulfuric acid (100 mL) and stirred at reflux for 3 hours. The acetamide 3b was separated from the reaction mixture by steam distillation to give the hydrolysis product of 2-methyl-6-nitroaniline (4b). After the distiller was cooled, the isolated bright orange needle-like crystals 4b were collected on a Brinell funnel and dried in a vacuum desiccator. If acetamide 3a was hydrolyzed, the warm reaction mixture was diluted with 350 mL of water and alkalized with 10% aqueous sodium hydroxide. After cooling to room temperature, 4-methyl-2-nitroaniline (4a) precipitated as a brown powder, which was separated by vacuum filtration, washed with three parts of 200 mL of water, and dried in a vacuum desiccator. The yields of compounds 4a and 4b were 53.6% (40.73 g) and 52.3% (39.78 g), respectively.