The general procedure for the synthesis of 2,3,5,6-tetrafluoroaniline from 4-amino-2,3,5,6-tetrafluorobenzonitrile was as follows: 867.6 grams of sulfuric acid with a mass fraction of 90% was added to the reactor, and the temperature was raised to 100°C. The reaction was carried out at a uniform rate. Under stirring, 482 g of 4-amino-2,3,5,6-tetrafluorobenzonitrile was added at a uniform rate, and the addition process was controlled to be completed within 2 hours. After the addition was completed, the reaction temperature was maintained at 100 °C to continue the reaction for 3 hours. Subsequently, 165 g of water was added to the reaction system, the sulfuric acid concentration was diluted to 80%, and the reaction temperature was raised to 120 °C and maintained at this temperature for 10 hours. After that, the reaction temperature was further increased to 130°C and the reaction was continued for 5 hours. Upon completion of the reaction, the reaction system was cooled to room temperature. Under the cooling condition, 300 g of water was added to the reaction system, and then 1715 g of 45% aqueous sodium hydroxide solution was slowly added dropwise for neutralization until the pH reached 9. After the neutralization was completed, the temperature was raised for distillation, and ultimately, 410 g of a white solid product 2,3,5,6-tetrafluoroaniline was obtained with a purity of 99.8% and a yield of 98%.
