FORMATION OF SODIUM DITHIONITE FROM SODIUM AMALGAM AND SULFUR DIOXIDE IN NONAQUEOUS MEDIA

The formation of sodium dithionite (Na2S2O4) was studied in hydrocarbons, alcohols, ethers, amides, and dimethyl sulfoxide, using sulfur dioxide and sodium amalgam (0.3% Na by weight in Hg) as raw materials. Direct contact of the reactants gave yields of Na2S2O4 exceeding 90% in dimethylformamide and 80% in dimethyl sulfoxide. Some dispersion of the amalgam and overreduction of the SO2 were encountered. Evidence was found for the existence of high concentrations of radical-ion intermediates in several solvents. Formal compositions of these radical ions were determined from stoichiometric and other considerations. Reaction mechanisms involving these species are proposed. © 1969, American Chemical Society. All rights reserved.