The Mechanism of Accelerator Action. Reaction of Mercaptobenzothiazole with Sulfur

Abstract The investigation of the reaction of sulfur with mercaptobenzothiazole (MBT) is of great interest from the point of view of clarifying the mechanism of the action of the latter as a vulcanization accelerator. We studied the reaction of MBT with elemental sulfur in the melt and in solvent media—vaseline oil and xylene. The course of the reaction was followed by means of the H2S liberated, which was removed from the reaction medium by a continuous stream of nitrogen and was absorbed in a solution of CdCl2. In Figure 1 are presented the kinetics of the liberation of H2S on heating the mixture in a medium of vaseline oil, the concentration of MBT and sulfur comprising, respectively, 0.06 mole/liter and 0.655 g-atom/liter. This ratio and concentration of reactants corresponds to those in the vulcanization of rubber. As can be seen, the splitting out of H2S under the stated conditions proceeds at a constant rate, which can be explained by the very insignificant change in concentrations of reactants ove...