Sulfur preparations adverse effects

An aqueous solution of sulfuric acid and a salt of periodic add, trisodium paraperiodate, or one of the potassium periodates, has been used frequently as a substitute for pure periodic add. When the product of the oxidation reaction is to be isolated, the effect of the presence of metal ions on the yield should be considered. If the product is volatile or slightly soluble, or is isolated either as a slightly soluble derivative or by extraction with organic solvents, the presence of metal ions should not reduce the yield. In the Case of certain methylhexosides34 which were oxidized by periodic acid formed from potassium metaperiodate and an equivalent of sulfuric add in aqueous solution, the presence of potassium ions was found to cause a low yield of the crystalline strontium salt prepared by the strontium hypobromite oxidation of the dialdehyde resulting from the periodic add reaction. Oxidation by pure periodic add, a solution of which is prepared either from crystalline paraperiodic add or by the previously mentioned method from potassium metaperiodate, is desirable when the presence of difficultly removed metal ions affects the yield adversely. 

The S—A-S mixtures should be prepared and mixed while the materials are between about 260 and 320°F. The former represents the melting (solidification) point plus a tolerance to avoid sulfur structuring effects, and the latter is the temperature above which sulfur undergoes an abrupt and very large increase in viscosity as shown in Figure 2. Although these viscosity changes are perfectly reversible (2), they do adversely affect the workability of the mix above about 325°F. However, as will be shown later, acceptable mixes were prepared at sulfur temperatures... 

---