Oxidation to peroxides

The trityl radical (gold-coloured) is readily oxidized to peroxide (white) the comparable 2,4,6-tri-(tert-butyl)phenoxy radical (blue) in, e.g., cyclohexane was applied by Paris et al." to so-called free radical titration (either potentiometric or photometric) of oxygen or antioxidant (the latter by hydrogen abstraction). 

As already indicated when protein structure is damaged, hsps may repair it. As well as reduction by vitamin E as described, lipids damaged by oxidation to peroxides can be broken down by phospholipase A2 and the fatty acid peroxide replaced. 

Ethers can also be oxidized to peroxides, but this is unlikely to be on the MCAT. 

Oxygen bound in peroxides or complexes can initiate or accelerate polymerizations. Some monomers, e. g. vinyl acetate, are oxidized to peroxidic compounds. Initiating radicals are liberated by thermal decomposition of peroxides. 

White oils, containing no significant levels of aromatics or sulfur-containing compounds, have no antioxidant capability and will undergo oxidation to peroxides and hydroperoxides readily and at the same time show no visible signs of chemical change. Therefore storage conditions should be maintained at ambient temperatures. Because of this instability, addition of an antioxidant such as butylated hydroxytoluene (BHT) or vitamin E is permitted in some jurisdictions. 

Photochemical oxidation of acetone at room temperature yields peroxide [119,120], acids [119—121] (acetic acid [121]), aldehydes [119—121] (in particular formaldehyde [121]), and C02 [120]. Methane and ethane are produced in small amounts [120], Under pressure at 180— 200°C, acetone is oxidized to peroxide (apparently CH3COCH2OOH), methylglyoxal, formaldehyde, acetic and formic acids, H20, and C02 [122], The oxidation produces, after 400 min, 0.25 mole l"1 methylglyoxal, 6 X 10"3 mole l-1 formaldehyde, 1.05 mole l-1 acetic acid, and 0.14 mole l-1 formic acid at 190°C and a pressure of 40 atm. The conversion to oxidation products occurs by two parallel routes [122]... 

The explosion hazards of low aliphatic ethers caused by peroxide formation are not manifested by the haloethers. The halogens inhibit the ether oxidation to peroxides. 

Trimethylamine, CjH N, (CH3J3N. Colourless liquid with a strong fishy odour, miscible with water, m.p. — I24 C, b.p. 3-5°C. It occurs naturally in plants, herring brine, bone oil and urine. It reacts with hydrogen peroxide to give trimethylamine oxide and with ethylene oxide to give choline its commercial importance stems chiefly from this latter reaction. 

Aldehydes are easily oxidized to carboxylic acids under conditions of ozonide hydroly SIS When one wishes to isolate the aldehyde itself a reducing agent such as zinc is included during the hydrolysis step Zinc reduces the ozonide and reacts with any oxi dants present (excess ozone and hydrogen peroxide) to prevent them from oxidizing any aldehyde formed An alternative more modem technique follows ozone treatment of the alkene m methanol with reduction by dimethyl sulfide (CH3SCH3)... 

The reaction follows a free radical mechanism and gives a hydroperoxide a compound of the type ROOH Hydroperoxides tend to be unstable and shock sensitive On stand mg they form related peroxidic derivatives which are also prone to violent decomposi tion Air oxidation leads to peroxides within a few days if ethers are even briefly exposed to atmospheric oxygen For this reason one should never use old bottles of dialkyl ethers and extreme care must be exercised m their disposal... 

H202 in preparation of [HYDROGEN PEROXIDE] (Vol 13) -oxidation to H202 fiYDROGEN PEROXIDE] (Vol 13)... 

Propylene oxide [75-56-9] is manufactured by either the chlorohydrin process or the peroxidation (coproduct) process. In the chlorohydrin process, chlorine, propylene, and water are combined to make propylene chlorohydrin, which then reacts with inorganic base to yield the oxide. The peroxidation process converts either isobutane or ethylbenzene direcdy to an alkyl hydroperoxide which then reacts with propylene to make propylene oxide, and /-butyl alcohol or methylbenzyl alcohol, respectively. Table 1 Hsts producers of propylene glycols in the United States. 

Fig. 6. Schematic ignition diagram for a hydrocarbon+ O2 mixture, with appHcations. Region A, very rapid combustion, eg, a jet engine region B, low temperature ignition, eg, internal combustion engine, safety ha2ards regions C and D, slow oxidation to useful chemicals, eg, 0-heterocycHc compounds in C and alcohols and peroxides in D. Courtesy of Blackwell Scientific PubHcations, Ltd., Oxford (60).

Mn (IT) is readily oxidized to Mn (ITT) by just bubbling air through a solution in, eg, nonanoic acid at 95°C, even in the absence of added peroxide (186). Apparently traces of peroxide in the solvent produce some initial Mn (ITT) and alkoxy radicals. Alkoxy radicals can abstract hydrogen to produce R radicals and Mn (ITT) can react with acid to produce radicals. The R radicals can produce additional alkylperoxy radicals and hydroperoxides (reactions 2 and 3) which can produce more Mn (ITT). If the oxygen feed is replaced by nitrogen, the Mn (ITT) is rapidly reduced to Mn (IT). 

Oxidation. Hydrogen peroxide is a strong oxidant. Most of its uses and those of its derivatives depend on this property. Hydrogen peroxide oxidizes a wide variety of organic and inorganic compounds, ranging from iodide ions to the various color bodies of unknown stmcture in ceUulosic fibers. The rate of these reactions may be quite slow or so fast that the reaction occurs on a reactive shock wave. The mechanisms of these reactions are varied and dependent on the reductive substrate, the reaction environment, and catalysis. Specific reactions are discussed in a number of general and other references (4,5,32—35). 

Berzehus (19) further appHed and amplified the nomenclature introduced by Guyton de Morveau and Lavoisier. It was he who divided the elements into metalloids (nonmetals) and metals according to their electrochemical character, and the compounds of oxygen with positive elements (metals) into suboxides, oxides, and peroxides. His division of the acids according to degree of oxidation has been Httie altered. He introduced the terms anhydride and amphoteric and designated the chlorides in a manner similar to that used for the oxides. 

Autoxidation of alkanes generally promotes the formation of alkyl hydroperoxides, but d4-tert-huty peroxide has been obtained in >30% yield by the bromine-catalyzed oxidation of isobutane (66). In the presence of iodine, styrene also has been oxidized to the corresponding peroxide (44). 

After apphcation to the fabric, the compounds are polymerized by reaction with gaseous ammonia (11,12), then oxidized to phosphine oxides by reaction with hydrogen peroxide. The stmcture of the polymer is shown (13). 

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