In a four-necked flask with a thermometer, stirrer, reflux condenser tube and nitrogen protection device, 35% (mass fraction, the same hereinafter) of sodium metabisulfite solution 326g was added, nitrogen protection, stirring was turned on, heated to 60-65.C, 90.6g of methacryloyl chloride was added dropwise to keep the reaction solution refluxing slightly. The pH was regulated in the range of 8 to 9 with sodium hydroxide solution during the reaction, and the reaction reached the end point when the reaction reached no methacryloyl chloride reflux. Add 50% (mass fraction) calcium chloride solution, stirring 10rain, so that the resulting calcium sulfate a calcium sulfite precipitation completely. Filter, get colorless transparent sulfonated liquid.
Reduced-pressure dehydration and concentration of sulfonated solution, when there are white crystals precipitated, stop heating, cooling, add appropriate amount of anhydrous ethanol, filtration to remove sodium chloride. The filtrate is heated, evaporated to remove the solvent, and the white solid product is sodium methane sulfinic acid crude product; the crude product is washed and recrystallized, and dried to get the finished product of sodium methane sulfinic acid.
