Oxidative degradation Hydrogen peroxide

As plastics age under thermal-oxidative load, there is a relationship between the increase in hydrogen peroxide concentration [ROOH] and the decrease in mechanical properties. Figure 1.43 At the start of thermal-oxidative degradation, hydrogen peroxide concentration is low. When hydrogen peroxide concentration increases... 

Kleno, J.G., Wolkoff, P., Clausen, P.A., Wilkins, C.K. and Pedersen, T. (2002) Degradation of the adsorbent Tenax TA by nitrogen oxides, ozone, hydrogen peroxide, OH radical and limonene oxidation products. Environmental Science and Technology, 36, 4121-6. 

The cyanide method is presently the only method for the determination of ketone groups in the polymers and was highly instrumental in the chemical characterization of degraded and oxidized celluloses. The use of this method enabled the development of the first two systems for the preparation of keto-cellulose, namely by mild oxidation with aqueous bromine at low pH values at room temperature [441,442] and by mild oxidation with hydrogen peroxide at pH 10 and 80°C [420,443]. 

Peroxisome is a cellular organelle where proteins and other molecules are oxidized. It contains enzymes that form and degrade hydrogen peroxide, (H2O2). 

The degradation product of the sulfonimn salt formed in the greatest yield after acid hydrolysis is undoubtedly a function of the structure of the affinity label. Generally, if the total amino acid composition of the modified protein was determined, low yields of methionine and increased yield of homoserine would be indicative, but certainly not proof of, the modification of a methionine residue. Sulfonium salts of methionine are generally not oxidized by hydrogen peroxide (Sigman and Blout 1967). 

Possible sources of ROS in the livers of rodents exposed to PPARa activators include enzymes that generate and degrade hydrogen peroxide and other ROS. Hydrogen peroxide can oxidize DNA, lipids, and other molecules, and PPARa activators regulate the expression of many enzymes that produce hydrogen peroxide as a byproduct of metabolism including the peroxisomal, mitochondrial, and microsomal oxidases in hepatocytes such as fatty acyl-CoA oxidase (ACO) (Becuwe and... 

Samples of [S- CH ] aldicarb, aldicarb sulfoxide and aldicarb sulfone were incubated with samples of groundwater and aquifer sediments to examine the potential for microbial degradation in situ in groundwater. The [S - XH3] aldicarb was provided by Union Carbide Agricultural Products Company the labeled sulfoxide was prepared from this by oxidation with hydrogen peroxide, the sulfone from the aldicarb by oxidation with peroxyacetic acid. These oxidants afforded better yields of cleaner product than the nr chloroperoxybenzoic acid previously used (18). 

The oxidative degradation of triazine herbicides like Atrazine [2-chloro-A4-ethyl-V6-iso-propyl-1,3,5-triazine-4,6-diamine (15)] can be effected by hydroxyl radicals generated from ozone, metal oxides or hydrogen peroxide/iron(II) salts (Fenton s reagent).22... 

The Ruff degradation is the opposite of the Kiliani-Fischer synthesis. Thus, the Ruff degradation shortens an aldose chain by one carbon Hexoses are converted into pentoses, and pentoses are converted into tetroses. In the Ruff degradation, the calcium salt of an aldonic acid is oxidized with hydrogen peroxide. Ferric ion catalyzes the oxidation reaction, which cleaves the bond between C-1 and C-2, forming CO2 and an aldehyde. It is known that the reaction involves the formation of radicals, but the precise mechanism is not well understood. 

Hazardons aromatics are destroyed by thermal processes that inclnde incineration of the hqnid hydrocarbons or their solntions in combnstible solvents. Anaerobic microbial degradation in the presence of high concentrations of dissolved oxygen in waste-water and oxidation with hydrogen peroxide or ozone in the presence of UV light are some of the methods reported in the hter-atnre to destroy mononnclear aromatics snch as benzene and tolnene. 

Much controversy has centered around the structure and source of arborine 36, 41). The elucidation of structure (2) (Chart 1) by degradation and synthesis was described in part in a previous chapter in this series 169). Chakravarti et al. 36) proposed the benzylquinazolinone structure (2), whereas Chatterjee and Ghosh Majumdar 42) preferred formula (14) because ozonolysis or periodic acid oxidation of arborine yields benzal-dehyde. The yield of benzaldehyde obtained by these methods, or by oxidation with hydrogen peroxide, is extremely low 34) whereas phenyl-acetic acid may be obtained in almost quantitative yield. The controversy was resolved by Chakravarti et al. 37) on the basis of the physical properties of arborine. Ultraviolet absorption studies and a detailed critical study of the infrared absorption spectra of arborine, dihydroarborine and model compounds of unambiguously defined structure including N-methylanthranilamide, 1,2-dimethylquinazolin-4-one, 2,3-dihydro-l,2-di-methylquinazolin-4-one, 2-ethyl-l-methylquinazolin-4-one, 2,3-dihydro-2-ethyl-l-methylquinazolin-4-one strongly supported structure (2) for arborine. 

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