The general procedure for the synthesis of 3-chloro-5-nitrotoluene from 2-chloro-6-methyl-4-nitroaniline was as follows: 2-chloro-4-nitro-6-methylaniline (55.0 g, 0.295 mol) was mixed with ethanol (500 mL) in a 2 L four-neck flask. Sulfuric acid (120 mL) was added slowly and dropwise to the reaction mixture at below room temperature. The temperature of the reaction mixture was maintained at 5 to 10 °C and an aqueous sodium nitrite solution (26.44 g, 0.381 mol dissolved in 40 mL of water) was added dropwise over 40 min. Subsequently, the reaction mixture was stirred at room temperature. After the reaction was observed to be exothermic raising the temperature to 45 °C, it was cooled naturally to below 40 °C and stirring was continued at 40 to 45 °C until no bubbles were produced. After cooling the reaction mixture to room temperature, it was poured into 2500 mL of ice water and precipitated. The precipitate was collected by filtration and dried under reduced pressure to give 45.95 g of yellow solid product in 90% yield. The product was characterized by 1H-NMR (500 MHz, CDCl3): δ 8.03 (broad peak, 1H), 7.94 (broad peak, 1H), 7.50 (broad peak, 1H), 2.46 (single peak, 3H).
