450Kg of concentrated sulfuric acid was added to the reactor, the temperature of the reaction solution was room temperature, the reaction solution containing the intermediate 1 was slowly added dropwise, and after sufficient stirring, 75 kg of 70% nitric acid was slowly added. After stirring until completion of the reaction, 800kg of crushed ice was added to the reaction solution and stirred constantly , Finally, pH was adjusted to 7~8 with ammonia solution to give crude product after filtration, crude product was recrystallized from methyl ethyl ketone to give 140 Kg of Intermediate 2, with a yield of 81.5%.
