The Chemistry of Vulcanization. IV. Action of 2-Mercaptobenzothiazole on the Reaction of Diphenylmethane and Sulfur

Abstract

Abstract In Part I of this series, the mechanism of the reaction of diphenylmethane (DPM) and sulfur was discussed, and in Part II, a kinetic investigation was carried out. In this paper, the mechanism and kinetics of the reaction involving DPM, sulfur and 2-mercaptobenzothiazole (MBT) will be reported and compared with those of Parts I and II, respectively. Thus the accelerating effect of MBT has been elucidated clearly. DPM which has no olefinic double bonds but which has α-methylenic hydrogen adjacent to aromatic double bonds has been shown to be an excellent model for studying the mechanism of acceleration by the methods of organic chemistry. The significance of DPM as a model of rubber hydrocarbon in the presence of sulfur alone was discussed in Part I. British investigators using olefins such as dihydromyrcene and squalene as models studied the mechanism of acceleration. However, they could not deduce the mechanism so clearly as we in this paper, only because the reaction of olefins with sulfur seemed to be more complex than that of DPM. Investigations on the reaction of DPM, sulfur and accelerators in the presence of either zinc oxide or zinc soap will be reported in other papers of this series.