1) In a 500 mL four-neck flask equipped with a thermometer, mechanical stirrer and exhaust gas absorption device, 246 g (2.0 mol) of nitrobenzene and 139 g (1.2 mol) of chlorosulfonic acid were added. Stirring was initiated and heated to 120 °C, and the sulfonation reaction was maintained at this temperature for 3 hours. The hydrogen chloride gas generated during the reaction was introduced into 200 mL of deionized water through the tail gas absorption device, and finally an aqueous hydrogen chloride solution with a mass concentration of 17.5% was obtained.
(2) After the reaction was completed, the reaction mixture was cooled to room temperature, 500 mL of water and 63.6 g (0.6 mol) of sodium carbonate were added and stirred thoroughly. The oil layer was separated after standing. The oil layer was washed three times with 500 mL of water and subsequently dried over 35 g of molecular sieves to give 95 g of recovered nitrobenzene with 99.3% purity. The aqueous layer solution was dried by a spray drying unit (feed rate 15-20 mL/min, inlet temperature 300 °C, outlet temperature 100 °C) to give 266 g of dried sodium nitrobenzenesulfonate product with 99.0% purity and 98.4% yield (in terms of consumed nitrobenzene).
