The role of thiol intermediates in 2‐mercaptobenzothiazole accelerated sulfur vulcanization of rubber model compounds

Abstract

The model compound, 2,3-dimethyl-2butene (TME), was vulcanized using 2-mercaptobenzothiazole (MBT) and sulfur. MBT was not consumed during the vulcanization reaction. The resultant crosslink products were bis(alkenyl) in nature. 2,3-Dimethyl-2-buten-1-thiol (TME-SH) was identified as being present in the vulcanization mixture by a postcolumn derivatization technique. The appearance of thiol was coincident with crosslinking. Polysulfanes (H 2 S n ) were formed on crosslinking. Studies of the reaction of TME-SH and sulfur indicated a rapid reaction to form crosslink products and polysulfanes. No monosulfidic crosslink species were formed in these reactions. Closer investigation revealed the presence of small quantities of what appeared to be highly reactive polysulfidic thiols. This is the first time that such species have been identified in vulcanization systems. Consequently, MBT-accelerated vulcanization of TME is proposed to occur via the reaction of MBT and S 8 to form polysulfidic MBT, which then reacts with TME to form polysulfidic thiols. These thiols then rapidly react via a metathesis reaction pathway to provide crosslink products and polysulfanes.

The tensile properties of strain‐crystallizing vulcanizates. III. The superiority of conventional over peroxide vulcanizates in terms of network microstructure

“…More recent studies have shown that disproportionation occurs slowly in the absence of zinc compounds, while pendent group‐chain reactions are limited 21. Instead, crosslinking results from reaction between accelerator terminated polysulfidic pendent groups and polysulfidic thiols 24–27. Polysulfidic thio pendent groups may form via exchange reactions19, 24, 28 between polysulfidic pendent groups and thio acids liberated on pendent group formation, while on reaction with sulfur the thio acids themselves can act as accelerators 19, 25, 27.…”

“…Polysulfidic thio pendent groups may form via exchange reactions19, 24, 28 between polysulfidic pendent groups and thio acids liberated on pendent group formation, while on reaction with sulfur the thio acids themselves can act as accelerators 19, 25, 27. In MBTS systems, the thio‐acid is MBT, a known accelerator 26…”

Mathematical Modeling for the Industrial 2-Mercaptobenzothiazole Batch Production Process

“… 1 Traditionally, MBT was extensively used as an accelerator in the rubber vulcanization process. 2 Later, the capability of MBT for inhibiting metal corrosion was discovered, and biological applications of MBT as a fungicide were also investigated. 3 , 4 In recent research studies, new functions of MBT and its derivatives have been disclosed that suggest it can be used in the modified Julia olefination reaction, which is an effective tool for advance fragment linkage.…”

Preparation and characterization of functionalized Cu(II) Schiff base complex on mesoporous MCM-41 and its application as effective catalyst for the oxidation of sulfides and oxidative coupling of thiols

“…Sulfoxides are valuable synthetic intermediates for the production of a range of chemically and biologically active molecules including therapeutic agents such as psychotropic and vasodilators, antibacterial [11], antiulcer (proton pump inhibitors) [12], cardiotonic, antihypertensive and a agents as well as anti-atherosclerotic, antifungal [13]. In the other hand the oxidative coupling of thiols to the corresponding disulfides is an important reaction in chemical and biologically processes including vulcanization [14], protein thiol oxidation in tumor cells [15] and vascular smooth muscle cells [16]. Oxidation is the easiest way for the preparation of sulfoxides and disulfides.…”