Oxidative-reductive depolymerization

Corrosive attack by organic carboxylic acids on polybutadiene binder is exhibited by oxidization and depolymerization processes, with the resulting the formation of carboxyl groups COOH. Carboxylic acids generally are weaker than inorganic acids because the speed of these processes is lower and, therefore, the decrease of physical-mechanical properties of RubCon occurs more slowly. The most intensive reduction of RubCon strength properties (compressive strength and modulus of elasticity) due to carboxylic acids attack were noted in the first 90 days. Penetration depths of... 

Cigarette smoke composition is dependent on two major processes occurring during the smoking of tobacco the direct transfer by vaporization of volatile tobacco components directly to the smoke and the pyrogenesis of smoke components from tobacco components. The pyrogenesis involves a variety of reactions, including oxidation, reduction, aroma-tization, hydration, dehydration, condensation, cyclization, polymerization, depolymerization, etc. 

Fig. 14 Schematic representations of the oxidative polymerization and reductive depolymerization on the nanotube of self-assembled 8e...

By using this technique acrylamide, acrylonitrile, and methyl acrylate were grafted onto cellulose [20]. In this case, oxidative depolymerization of cellulose also occurs and could yield short-lived intermediates [21]. They [21] reported an electron spin resonance spectroscopy study of the affects of different parameters on the rates of formation and decay of free radicals in microcrystalline cellulose and in purified fibrous cotton cellulose. From the results they obtained, they suggested that ceric ions form a chelate with the cellulose molecule, possibly, through the C2 and C3 hydroxyls of the anhy-droglucose unit. Transfer of electrons from the cellulose molecule to Ce(IV) would follow, leading to its reduction... 

Understanding in detail the chemistry of CO and CO-H2O mixtures over metal oxide surfaces has considerable importance for a number of reasons (1) CO-H2O is a more effective reducing medium relative to pure H2 for reduction and depolymerization of low rank coals where metal oxides and other minerals can act as in situ catalysts 48,49,50, 51,52) (2) CO-H2O is better than H2 for the reduction of some organic functional groups (53,54) (3) some metal oxides, especially basic oxides, are used as promotors in Fischer-Tropsch catalytic chemistry and their role is not understood mechanistically (55,56,57) and (4) metal oxides are often used as catalysts for the CO + H2O CO2 + H2 water-gas shift reaction (e.g., see Ref. 58 see also Ref. 59). 

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