2-Nitro-4-methylsulfonylbenzoic acid

1671-49-4

110964-79-9

The general procedure for the synthesis of 2-nitro-4-methylsulfonylbenzoic acid from 2-nitro-4-methylsulfonyltoluene was as follows: 600.00 g of sulfuric acid with a mass fraction of 70% was added to a 1000 mL glass reactor, and a self-priming mixing device was activated. Subsequently, 97.83 g of 2-nitro-4-methylsulfonyltoluene with 99% purity and 1.95 g of vanadium pentoxide powder with 98% purity were added to the reactor and stirred continuously for 10 minutes. A condensation receiver with exhaust gas absorption was installed. The reaction system was rapidly heated to 140°C, and 230 g of nitric acid with a mass fraction of 68% was slowly added, while the oxygen feed rate was controlled to be 0.1 g/min, and the acceleration rate of the nitric acid droplet was 0.383 g/min, and the droplet addition was completed in about 10 hours. After completion of the dropwise addition, the reaction temperature is maintained at 140°C and stirring is continued until the mass fraction of unreacted 2-nitro-4-methylsulfonyltoluene is reduced to 1% or less (about 1 hour from the end of the dropwise addition to the completion of the reaction). The reaction solution was slowly cooled to 10-20°C with stirring and the product was separated by filtration. The filter cake was washed three times with 150 g of water and dried to give 110.20 g of 2-nitro-4-methylsulfonylbenzoic acid in 98.10% purity and 98.0% yield. 205 g of nitric acid with a mass fraction of 60% was recovered, which could be reused after evaporation and concentration. The small amount of nitrogen oxide exhaust gas generated during the reaction process was treated by air oxidation and absorption through an absorption device equipped with a 32% mass concentration of sodium hydroxide solution.