121-91-5

618-88-2

The general procedure for the synthesis of 5-nitroisophthalic acid from isophthalic acid is as follows: concentrated sulfuric acid (120 mL, 2.21 mol) was added to a three-neck flask, followed by isophthalic acid (80 g, 0.48 mol). The mixture was heated to 75 °C and maintained at this temperature for 0.5 h under stirring conditions. 60% nitric acid (73.5 g, 0.70 mol) was slowly added dropwise, with the rate of acceleration of the drop being controlled to ensure completion of the drop within 2 to 2.5 hours. After the dropwise addition was completed, the reaction mixture was continued to be stirred at 75 °C for 2 hours. Subsequently, the temperature was raised to 90 °C and the reaction continued for 1 hour. Upon completion of the reaction, the mixture was cooled to below 50 °C and 120 mL of water was slowly added dropwise. The mixture was further cooled to room temperature, filtered, and the spent acid was removed by filtration. The filter cake was washed three times with pure water to remove the wash water. Pure water (120 mL) was added to the filter cake, stirred and heated until dissolved, stirring the mixture thoroughly. Hot filtration was carried out, cooled and crystallized, and the filter cake was dried to give a white crystalline solid 5-nitroisophthalic acid (89.6 g) in 88.3% yield.