The Molecular Nature of the Hydrophilic Sulfur Prepared from Aqueous Sulfide and Sulfite (Selmi Sulfur Sol) [1]

Hydrophilic sulfur sols prepared by reaction of aqueous sulfide and sulfite at low pH have been studied by chemical analysis, ion-pair chromatography, and reversed-phase HPLC. The approxi­ mate composition of the sol is x (N a H S 0 4/N a;S 0 4) • vS„ • zN a2S,„Oh with n = 6 —10 and m = 4 —16. The elemental sulfur S„ accounts for 17% and the polythionate sulfur for 10% of the dry weight (sulfate: 18%). On aging of the sol at 20 °C the long-chain polythionates decom pose to elemental sulfur and tetrathionate as well as pentathionate. The higher chemical reactivity of this sol compared to Sx is explained by the fact that 45% of the zero oxidation state sulfur (S°) are present as non-S8 molecules.