General procedure for the synthesis of 2-chloro-5-nitrotoluene from 4-nitro-2-methylaniline: First, 152 kg of 2-amino-5-nitrotoluene was dissolved in 600 kg of concentrated sulfuric acid, followed by the addition of 150 kg of water, and naturally heated to 100°C. After the reaction solution was completely dissolved, the temperature was lowered to 300 kg of industrial hydrochloric acid at a concentration of 30%. After 2-amino-5-nitrotoluene was completely dissolved, the temperature was lowered and 300 kg of industrial hydrochloric acid with a mass concentration of 30% was added, during which it was necessary to ensure that the temperature of the reaction solution did not exceed 0°C. The temperature of the reaction solution was then increased by 27 kg at a constant rate. Next, 276 kg of a 25% sodium nitrite solution was added at a constant rate to produce the diazonium salt solution. In another reactor, 450 kg of industrial hydrochloric acid was added and 225 kg of cuprous chloride was dissolved with stirring, and the temperature was reduced to below 20°C after dissolution. The prepared diazonium salt solution was quickly added to this reactor for rapid stirring and hydrolysis reaction. The reaction mixture was held for 2 hours before being warmed up to 55°C and maintained at this temperature for 2 hours. Finally, water vapor was distilled out by increasing the temperature until 160 kg of 2-chloro-5-nitrotoluene was collected in 93.3% yield.
