In a four-necked flask equipped with a thermometer, a stirrer, a reflux condenser and a nitrogen protection device,
first add 326g of 35% (mass fraction, the same below) sodium pyrosulfite solution, under nitrogen protection, start stirring,
and heat to 60-65. C,then drop 90.6g of methanesulfonyl chloride to keep the reaction solution slightly refluxed.
During the reaction,the pH value is adjusted in the range of 8-9 with sodium hydroxide solution.
When the reaction is completed without methyl propylene chloride reflux,the reaction reaches the end point. Add 50% (mass fraction)
calcium chloride solution and stir for 10min to completely precipitate the generated calcium sulfate-calcium sulfite.
Filter to obtain a colorless and transparent sulfonated liquid.Dehydrate and concentratethe sulfonated liquid under reduced pressure.
When white crystals precipitate, stop heating, cool,add an appropriate amount of anhydrous ethanol, and filter to remove sodium chloride.
The filtrate is heated and the solvent is evaporated to obtain a crude white solid product of sodium methanesulfinate;
the crude product is washed,recrystallized and dried to obtain a finished product of sodium methanesulfinate. |
