Production Methods
3-Nitrobenzenesulfonic acid is produced by dissolving nitrobenzene in 98 % sulfuric acid and heating to 80 ℃. Then 65 % oleum is added at this temperature, and the reaction is completed by heating for 9 h at 105 ℃ (higher temperatures are unsafe). After quenching the sulfonation mass in water, neutralizing with lime, and filtering off gypsum, the calcium salt of the product is converted to the sodium salt with sodium carbonate. After calcium carbonate has been removed by filtration, the sodium salt solution can be used directly or evaporated.
