Peroxide decomposition, acid catalyzed

Phenol formed in the system due to acid-catalyzed decomposition of hydroperoxide retards the cumene oxidation. The aqueous phase withdraws phenol from the hydrocarbon phase. This is the reason why the emulsion oxidation of cumene helps to increase the yield of hydroperoxide. The addition of hydrogen peroxide into the system helps to increase the yield of hydroperoxide. 

The reactions of sulfides with ROOH give rise to products that catalyze the decomposition of hydroperoxides [31,38-47]. The decomposition is acid-catalyzed, as can be seen from the analysis of the resulting products cumyl hydroperoxide gives rise to phenol and acetone, while 1,1-dimethylethyl hydroperoxide gives rise to 1,1-dimethylethyl peroxide, where all the three are the products of acid-catalyzed decomposition [46-49]. It is generally accepted that the intermediate catalyst is sulfur dioxide, which reacts with ROOH as an acid [31,46-50]. 

The reagent can be prepared in situ, by the copper-catalyzed oxidation of hydrazine. Hydrogen peroxide or oxygen are often the oxidants. The acid-catalyzed decomposition of potassium azodicarboylate provides a useful source of diimide ... 

Fe2+. Because peroxide decomposition was slowest under the same conditions at which benzoic acid decomposition was highest, it is important to consider the efficiency of hydroxyl radical formation from peroxide decomposition. With the surface catalyst, either hydroxyl radical is not readily available to benzoic acid and is scavenged by other species, or the mineral-catalyzed decomposition of hydrogen peroxide involves additional, nonhydroxyl radical-forming pathways for peroxide decomposition. 

Instead of either an acid-induced decomposition or acid-catalyzed sulfur compound—hydroperoxide decomposition reaction occurring— formation of alternative active species which catalytically decompose the hydroperoxide is possible, such as SCL, as suggested by Hawkins and Sautter (4). However, under conditions of this work where vigorous drying of solvents was not used, SOL could be converted into the acid which would then induce the acid-catalyzed decomposition of the peroxide. 

The most numerous cases of homogeneous catalysis are by certain ions or metal coordination compounds in aqueous solution and in biochemistry, where enzymes function catalytically. Many ionic effects are known. The hydronium ion H3O and the hydroxyl ion OH catalyze hydrolyses such as those of esters ferrous ion catalyzes the decomposition of hydrogen peroxide decomposition of nitramide is catalyzed by acetate ion. Other instances are inversion of sucrose by HCl, halogenation of acetone by H and OH , hydration of isobutene by acids, hydrolysis of esters by acids, and others. 

In addition to the S(IV) —H202 reaction, the reactions of other peroxides such as peroxymonosulfate, peroxyacetic acid, and methyl hydroperoxide with S(IV) are also sensitive to specific-acid catalysis (Hoffmann and Calvert, 1985). The rate of oxidation of S(IV) by HSO / is comparable to the rate of oxidation of S( IV) by hydrogen peroxide (Betterton and Hoffmann, 1988). We have proposed a general mechanism for the ROOH-S(IV) reaction in which the rate-determining step involves the acid-catalyzed decomposition of a peroxide-bisulfite intermediate. The rate expression applicable for this mechanism is... 

Peroxide (hydrogen peroxide, peracetic acid) Bacteria, fungi, viruses, and spores 3-7.5 50-500 ppm 0.5-5.5 Catalyzed decomposition by heavy metals like iron... 

The initial products derived from lipid peroxidation are subject to decomposition reactions, which may be facilitated by the presence of metals and other one-elec-tron-donating species. In particular, the lipid hydroperoxide and bicyclic endoper-oxide products are susceptible to degradation. Bicyclic endoperoxides undergo acid-catalyzed ring-scission across the endoperoxide to yield the three-carbon dial-dehyde, malondialdehyde (MDA) (Figure 5.1) [2]. MDAis also produced enzymatically from the endoperoxide-metabolizing enzyme thromboxane synthase [3, 4]. MDA is an abundant product of lipid peroxidation and reacts with DNA nucleophiles (see discussion below). 

The complexity of the peroxide curing system arises from a range of possible side reactions such as /3-cleavage of the oxy radical, addition reaction, polymer scission, radical transfer, dehydrohalogenation, oxygenation, and acid catalyzed decomposition of the peroxide." ... 

Interestingly, the most efficient chemiluminescent reaction so far observed during acene endo-peroxide decomposition has been exhibited by the 1,4-endo-peroxide (41) [38]. However, this very efficient chemiluminescence evidently requires treatment of (41) with acids, and it has been shown [45] that it is not the direct decomposition of the endo-peroxide to yield (43) that produces most of the excitation energy, but the acid catalyzed cleavage of (41) to yield the compounds (44) and (45). The reaction itself had been previously described [46-47]. 

The radicals are then involved in oxidations such as formation of ketones (qv) from alcohols. Similar reactions are finding value in treatment of waste streams to reduce total oxidizable carbon and thus its chemical oxygen demand. These reactions normally are conducted in aqueous acid medium at pH 1—4 to minimize the catalytic decomposition of the hydrogen peroxide. More information on metal and metal oxide-catalyzed oxidation reactions (Milas oxidations) is available (4-7) (see also Photochemical technology, photocatalysis). 

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