MANUFACTURE OF SODIUM DITHIONITE

摘要

In a process for the manufacture of sodium dithionite by reacting sulfur dioxide with sodium formate and aqueous sodium hydroxide solution in the presence of methanol, an aqueous methanolic solution of sodium formate is first produced by reacting carbon monoxide with sodium hydroxide solution in an aqueous medium, containing from 1 to 50% by weight of methanol, based on the amount of water, at from 80 to 120.degree.C under a pressure of from 10 to 40 bars. The resulting aqueous methanolic solution can be reacted directly, in the conventional manner, with sulfur dioxide and aqueous sodium hydroxide solution to give sodium dithionite. The process has the advantage that in the first step the reaction gives, within a short period and at a relatively low temperature, aqueous methanolic solutions of sodium formate, which in the second step can be directly converted to sodium dithionite.