Degradation hydroperoxide

Reaction 9 Thermal Oxidative Degradation - Hydroperoxide Formation [105]... 

Products of degradation hydroperoxides, unsaturations and products of their degradation, crossiinks, chain scission, caboxyiic acids, aicohois, aidehydes, and radicais ... 

Products of degradation - hydroperoxides, hydroxyl groups, polyene sequences, aldehyde, acetic acid ... 

Products of degradation hydroperoxides, radicals, ketones, carboxyl groups, hydroxyls, peresters, esters, lactones, chain scission, crosslinking, hydroxyls, double bonds ... 

Important initiators and accelerators - products of thermal degradation, hydroperoxides, phenyl radicals, phenoxy radicals, benzyl radicals, hydroxyl groups ... 

Products of degradation hydroperoxides, hydroxyl, carboxyl, ketone, and epoxy groups butadiene is degraded Arantes, TM Leao, K V Tavares, M I B Ferreira, A G Longo, E Camargo, E R, Polym. Test., 28, 490-94, 2009. 

Products of degradation hydroperoxides, hydroxyl, radioals, ohain soission Torikai, A Hozumi, A Fueki, K, Polym. Deg. Stab., 16, 13-24, 1986. 

Oxylipins are commonly found metabolites in higher plants and most of them originate from polyunsaturated fatty acid hydroperoxides by enzymatic transformations which have been extensively studied (for recent reviews, see 1,2). Two well characterized enzymes a lyase and an allene oxide synthase were shown to degrade hydroperoxides into compounds of physiological importance since they can ultimately yield fragrances or plant hormones such as jasmonic acid. We have recently reported a new fate for fatty acid hydroperoxides the peroxygenase pathway. It involves two enzyme activities i.e. a peroxygenase and an epoxide hydrolase which lead to the formation of epoxidized fatty acids and their derived dihydrodiols which are relevant to plant defense mechanisms. 

The fimction of an antioxidant is to divert the peroxy radicals and thus prevent a chain process. Other antioxidants fimction by reacting with potential initiators and thus retard oxidative degradation by preventing the initiation of autoxidation chains. The hydroperoxides generated by autoxidation are themselves potential chain initiators, and autoxidations therefore have the potential of being autocatalytic. Certain antioxidants fimction by reducing such hydroperoxides and thereby preventing their accumulation. 

Another method for slowing oxidation of rubber adhesives is to add a compound which destroys the hydroperoxides formed in step 3, before they can decompose into radicals and start the degradation of new polymer chains. These materials are called hydroperoxide decomposers, preventive antioxidants or secondary antioxidants. Phosphites (phosphite esters, organophosphite chelators, dibasic lead phosphite) and sulphides (i.e. thiopropionate esters, metal dithiolates) are typical secondary antioxidants. Phosphite esters decompose hydroperoxides to yield phosphates and alcohols. Sulphur compounds, however, decompose hydroperoxides catalytically. 

A recent communication described the cleavage of 17a-hydroperoxy-20-keto steroids with base to give 17-ketoandrostanes in good yield. Since such hydroperoxides are now accessible from 20-ketopregnanes in one step vide infra), this constitutes a convenient two-step degradation process. In practice, the intermediate hydroperoxide need not be isolated. Other enolizable... 

Many impurities are present in commercial caprolactam which pass into the liquid wastes from PCA manufacture from which caprolactam monomer may be recovered. Also, the products of die thermal degradation of PCA, dyes, lubricants, and other PCA fillers may be contained in the regenerated CL. Identification of die contaminants by IR spectroscopy has led to the detection of lower carboxylic acids, secondary amines, ketones, and esters. Aldehydes and hydroperoxides have been identified by polarography and thin-layer chromatography. 

Increase the oxidation rate of polymers, e.g. metal ions which increase the hydroperoxide decomposition rate. Photodegradation and thermal degradation are enhanced by transition metal ion containing pro-oxidants, such as iron dithiocarbamate (as opposed to nickel dithiocarba-mate, which acts as a photo-antioxidant). 

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