Benzothiazoles elemental sulfur with

The chemical microstructures of cis-polyisoprene (HR) vulcanised with sulfur and N-t-butyl-2-benzothiazole sulfenamide (TBBS) accelerator were studied as a function of extent of cure and accelerator to sulfur ratio in the formulations by solid-state 13C NMR spectroscopy at 75.5 MHz [29]. Conventional (TBBS/Sulfur=0.75/2.38), semi-efficient (SEV=1.50/1.50) and efficient (EV=3.00/1.08) vulcanisation formulations were prepared, which were cured to different cure states according to the magnitude of increase in rheometer torque. The order and types of the sulfurisation products formed are constant in all the formulation systems with different accelerator to sulfur ratios. However, the amount of sulfurisation has been found to vary directly with the concentration of elemental sulfur. 

The photoreactivity of benzothiazolethione (30) has been studied in several solvents in the presence of oxygen with and without methylene blue as a sensitizer. Disulfide, 2-oxo-derivative, benzothiazole, and elemental sulfur were the main products <87ZN(B)1153>. 

For some produets, elemental sulfur or sulfur-containing benzothiazole compounds are added to flie eompound as a euring agent. Sulfur reacts to form C-S-C bonds. This is an inexpensive reaetion seheme and it is useful for production of rubber compounds across a very wide hardness range. Residual sulfur eompounds lead to odors and acid products that are not well suited to applieations where elean materials are desired. Thiazole compounds provide better handling and more eontrollable erosslinking proeesses, with low residual odor and extraetables. 

Benzothiazoles have been generated by treating 2-halonitroarenes with elemental sulfur and benzylamines (Scheme 5.40 and Example 5.3) [62], This three-component reaction generated moderate to high yields of the benzothiazoles from a range of prefunctionalized... 

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