The interaction of sulphur and sulphur compounds with olefinic substances. VII Low‐temperature sulphuration of trialkylethylenes with hydrogen sulphide‐sulphur dioxide, and with a sulphur‐zinc dithiocarbamate system

The sulphuration of trialkylethylenes with hydrogen sulphide‐sulphur dioxide at 0° (Peachey process) results in disubstitutive cross‐linking of the olefins, yielding dialkenyl tetrasulphides. At higher temperatures substitutive—additive cross‐linking occurs and alkyl alkenyl polysulphides are formed. Dialkenyl tetrasulphides are similarly formed by causing the olefin to react with sulphur at room temperature in the presence of zinc oxide and zinc dibutyldithiocarbamate, low concentrations of hydrogen sulphide acting as a catalyst for this reaction. At higher temperatures the reaction is also exclusively disubstitutive, a feature connected with the function of zinc compounds in influencing the cross‐linking reaction. The sulphuration of olefins with tetramethylthiuram disulphide at 140° shows a similar influence of zinc compounds.