Peroxide agents

Subsequent studies confirmed that there is no reliable evidence of the MPO-catalyzed hydroxyl generation by neutrophils [235,236]. Kettle and Winterbourn [237] demonstrated that the hydroxylation of salicylate by stimulated neutrophils or the purified MPO, which yielded 2,5-dihydroxybenzoate, was unaffected by hydroxyl radical scavengers mannitol or DMSO. These authors suggested that an active peroxidative agent in this system was the reduced Compound III, formed by the following reactions ... 

Logani MK, Sambuco CP, Forbes PD, Davies RE Skin-tumour promoting activity of methyl ethyl ketone peroxide—a potent lipid-peroxidizing agent. Pood Chem Toxicol 22 879-882, 1984... 

It is now well documented that proteins are efficient cellular targets for peroxidizing agents including OH radical, peroxyl radical and singlet oxygen . Thus, evidence... 

Conversion to the Acid. Hydroxide and peroxide agents saponify acyl imides in excellent yields however, with ster-ically hindered acyl groups endocyclic cleavage may predominate upon treatment with Lithium Hydroxide. Lithium Hydroperoxide, however, is highly selective for the exocyclic carbonyl moiety. 

Enantioselective epoxidation of olefins is unique in that it creates two stereogenic centers. The catalyst is prepared quite easily by treating a titanium ( + 4) alkoxide with an (/ )- or (5)-diethyl tartrate (Gao et al., 1987). The peroxidation agent is usually t-butyl hydroperoxide. 

So, when conducting the reaction at 65-85 °C in water, alcohol, ester, acetonitrile, the polyketone particles of size 0.01-100 micrometers transform the polyesters by the oxidation under the peroxide agents per-oxybenzoic, m-chloroperoxybenzoic, peroxyacetic, trifloumperoxyacetic, monoperox rphthalic, monoperox5rmaleine acids, combinations of H2O2 and urea or arsenic acid [405, 406],... 

Tung, H.-C., Kang, C., and Sawyer, D.T. (1992) Nature of the Reactive Intermediates from the Iron-Induced Activation of Hydrogen Peroxide Agents for the Ketonization of Methylenic Carbons, tlie Monooxygenation of Hydrocarbons, and the Dioxygenation of Arylolefins, J. Am. Chem. Soc. 114, 3445-3455. 

The following reactions are examples of hydrogen peroxide used as an oxidising agent ... 

As the above redox potentials indicate, only in the presence of very powerful oxidising agents does hydrogen peroxide behave as a reducing agent. For example ... 

Although sulphur dioxide, as a gas, is a reducing agent in the sense that it unites with oxygen, free or combined (for example in dioxides or peroxides) most of its reducing reactions in aqueous solution are better regarded as reactions of sulphurous acid (in acid solution), or the sulphite ion (in alkaline solution). 

Addition of an oxidising agent to a solution of an iodide (for example concentrated sulphuric acid, hydrogen peroxide, potassium dichromate) yields iodine the iodine can be recognised by extracting the solution with carbon tetrachloride which gives a purple solution of iodine. 

Such a mechanism is supported by the fact that the reaction is accelerated by benzoyl peroxide and other radical-producing agents. It is now however considered that the function of the A -bromosuceinimide is to provide a constant, very low concentration of molecular bromine (Tedder et al,). 

Because of their use in the rubber industry various sulfenamido thiazoles (131) have been prepared. They are obtained in good yields through the oxidation of A-4-thiazoline-2-thiones (130) in aqueous alkaline solution in the presence of an amine or ammonia (Scheme 66) <123, 166, 255, 286, 308, 309). Other oxidizing agents have been proposed (54, 148. 310-313) such as iodine (152), chlorine, or hydrogen peroxide. Disulfides can also be used as starting materials (3141. 

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)... 

As we saw when discussing allylic brommation m Section 10 4 N bromosuccm imide (NBS) is a convenient free radical brommatmg agent Benzylic brommations with NBS are normally performed m carbon tetrachloride as the solvent m the presence of peroxides which are added as initiators As the example illustrates free radical bromi nation is selective for substitution of benzylic hydrogens... 

Destruction of the masking ligand by chemical reaction may be possible, as in the oxidation of EDTA in acid solutions by permanganate or another strong oxidizing agent. Hydrogen peroxide and Cu(II) ion destroy the tartrate complex of aluminum. 

Benzoyl peroxide Direct sunlight, sparks and open flames, shock and friction, acids, alcohols, amines, ethers, reducing agents, polymerization catalysts, metallic naph-thenates... 

Peroxides Reducing agents, organic materials, thiocyanates... 

PEROXIDES AND PEROXIDE COMPOUNDS - ORGANIC PEROXIDES] (Vol 18) -cross-linking agent pUBBERCITEMICALS] (Vol 21)... 

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