Peroxidation transition-metal catalysed

Non-drying vegetable oil-based poly(ester amide) resins require a long time period and a high temperature for curing by conventional transition metal catalysed peroxide systems, such as Co-/Mn-octate/naphthate with methyl ethyl ketone peroxide (MEKP), in the presence of styrene as a... 

Monosaccharides can oxidise when catalysed by trace amounts of transition metals, generating free radicals, hydrogen peroxide and reactive dicarbonyls directly [27]. The process of glucose oxidation can lead to protein damage by free radicals and by covalent binding of the carbonyl products of the process to protein components (see below) (Fig. 5). 

The Ruff degradation, in its classical version, conversion of the calcium salt of an aldonic acid to the aldose of one fewer carbon atoms by treatment with Fe and hydrogen peroxide, was one of the reactions used by Emil Fischer in his determination of the structure of the aldoses. Its success with Fe is mysterious, as one would expect Fenton chemistry involving HO to give molecular rubble, rather than good yields of a single product. However, the reaction is catalysed by transition metals in general (even with... 

When faujasites only exchanged with a transition metal are used as catalysts the oxidation of pinane at room temperature practically does not take place Transition metal ions are well known to catalyse the decomposition of organic peroxides [6]. Therefore, the low reactivity observed in those conditions is likely to be due to the decomposition of t-butyl-hydroperoxide before it can oxidise pinane... 

The above reaction is also catalysed by several transition metal ions and metal complexes provided the coordination sphere is accessible for H Oj and/or HOj. In our laboratory catalytic activity of transition metal ions and metal complexes supported on various zirconium based inorganic ion exchangers has been studied in detail for the disproportionation of hydrogen peroxide ". 

Oxidation of organic compounds using Hydrogen peroxide and tert.- BHP catalysed by polymer supported transition metal catalysts ... 

Superoxide anion is a relatively nonreactive species in aqueous solution, but in the presence of hydrogen peroxide and a transition metal such as iron, the extremely reactive hydroxyl radical may be generated through a superoxide anion-driven, metal-catalysed Fenton reaction. The hydroxyl radical is able to initiate lipid peroxidation directly through ab.straction of hydrogen from fatty acids leading to the formation of off-flavors and other undesirable compounds. 

Oxygen is omnipresent in our environment and the deterioration of rubbers and plastics by peroxidation is the normal cause of property deterioration in most polymers under ambient conditions. Peroxidation is a free radical chain reaction, shown in summary in reactions 3.1 and 3.2. Under normal conditions it is initiated by hydroperoxides that are formed in each cycle of the peroxidation chain sequence (reaction 3.1). Hydroperoxides are very unstable compounds due to the weakness of the peroxide bond which readily undergoes thermolysis when heated (reaction 3.3). This reaction is powerfully catalysed by transition metal ions. 

Transition metal prooxidants cause problems during both the manufacture and use of plastics products. Firstly they catalyse rheological changes in the polymer during processing and reduce shelf-life before use. Secondly it is difficult to control the induction time to photooxidation. It will be seen below that control of peroxidation is essential to the application of degradable plastics in agriculture. 

Bioerosion occurs without change in molar mass of the bulk polymer, confirming that the microbial attack is initially in the oxidation-modified polymer surface and progression into the polymer depends on the continuation of peroxidation catalysed by transition metal ions. The bacterial colonies also produce oxidase enzymes e.g. cytochrome P-450) which produce superoxide and hydrogen peroxide from oxygen of the environment. The latter in turn gives highly reactive hydroxyl... 

Although previous mention has been made of the oxidation of hydrogen peroxide by transition-metal ions, several studies have been involved with the metal-ion-catalysed decomposition... 

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