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Radial Tire Compound Polymer Blends
Published in Brendan Rodgers, Tire Engineering, 2020
A number of polymeric green strength promoters have been developed. The green strength promoter with commercial designation, Vestenamer 8012, is a polyoctenamer manufactured by Evonik GmbH of Germany. The raw material for this polymer is cyclooctene. In a metathesis polymerization reaction, cyclooctene is converted into a polyoctenamer. It was developed as a green strength promoter for tire sidewalls, apexes or bead fillers, and other components where dimensional stability is important. It meets four requirements: serving as a green strength promoter; rapid crystallization rate, low viscosity, and unsaturation for participation in the vulcanization or crosslinking reaction.
Synthesis, characterization, and catalytic oxidation of styrene, cyclohexene, allylbenzene, and cis-cyclooctene by recyclable polymer-grafted Schiff base complexes of vanadium(IV)
Published in Journal of Coordination Chemistry, 2018
Vijay Kumar Singh, Abhishek Maurya, Neha Kesharwani, Payal Kachhap, Sweta Kumari, Arun Kumar Mahato, Vivek Kumar Mishra, Chanchal Haldar
In synthetic organic chemistry, catalytic oxidation products of alkenes such as carbonyl compounds, epoxides, and diols are the major feedstock among the most effective synthetic intermediates in fundamental research as well as industrial commodities [1–4]. Particularly oxidation of cyclohexene, styrene, cis-cyclooctene, allylbenzene, etc. produces versatile and useful intermediates widely used in polymers, pharmaceuticals, fine chemicals, and biological materials [5–8]. Certain herbs and spices, like basil, cinnamon, nutmeg, ginger, black pepper, clove, tarragon, etc. carry naturally occurring allylbenzenes (such as eugenol, estragole, and safrole) in high concentration, which can be a promising green alternative source of renewable raw materials for chemical industry. Oxidation products of allylbenzenes are widely used in pharmacological, cosmetic, food, and fragrance industries [9–12] as well as direct synthetic intermediates in the production of biologically active compounds [13]. 2-Cyclohexene-1-ol and 2-cyclohexene-1-one formed through the allylic oxidation of cyclohexene are applied in the manufacture of spices, medication, pesticides, and insect pheromones [14, 15]. Oxidation of styrene is one of the most important research tasks for converting hydrocarbons into other valuable commodities such as benzaldehyde, styrene epoxide, and formaldehyde [16–20]. Styrene oxide is widely used for the synthesis of epoxy resin-diluting agents, ultraviolet absorbents, flavoring agents, etc.; benzaldehyde is a precious chemical mainly used in perfumery, pharmaceuticals, dyestuffs, and agrochemicals [21]. Likewise, the oxidation products of cyclooctene have widespread applications in industrially important pharmaceuticals and fine chemicals [22]. Conventionally, stoichiometric amount of oxidants such as permanganates, chromium reagents, ruthenium(VIII) oxide or activated DMSO were used to carry out the oxidation of alkenes. From the last few decades, metal complexes of Ti, V, Cr, Mn, Co, Ni, Cu, Mo, Ru, and Re were utilized for oxidation of alkenes in the presence of peroxides, peracids, and other oxidizing reagents [4, 23–30]. Vanadium complexes in high oxidation states have been widely used as effective catalysts in oxidation reactions of industrial as well as academic interest in the presence of a suitable oxidant [26, 30–34]. Moreover, the involvement of vanadium haloperoxidase, a vanadium-containing enzyme in a variety of biological processes, stimulated the application of vanadium-containing enzymes in various catalytic organic transformations [1–4, 23–38]. Flexible coordination number, easily interconvertible high oxidation states between +4 and +5, Lewis acidic nature of the vanadium center along with high affinity toward oxygen make high valent vanadium complexes promising agents for the catalytic oxidation of alkenes.