Reaction Mechanisms Hydrogen peroxide

In order to optimize the chemiluminescence response, we have investigated the mechanism of the complex reactions leading to chemical generation of chemiluminescence. A new peroxyoxalate-hydrogen peroxide reaction mechanism has emerged from our preliminary studies on the five contributing factors listed above. Two kinetic models are discussed, one for the... 

Great promise exists in the use of graphitic carbons in the electrochemical synthesis of hydrogen peroxide [reaction (15.21)] and in the electrochemical reduction of carbon dioxide to various organic products. Considering the diversity in structures and surface forms of carbonaceous materials, it is difficult to formulate generalizations as to the influence of their chemical and electron structure on the kinetics and mechanism of electrochemical reactions occurring at carbon electrodes. 

In accord with this mechanism, a single two-electron oxidation of the enzyme into Compound I by hydrogen peroxide (Reaction (8)) is followed by two one-electron steps Reaction (9), in which substrate RH is oxidized to a radical R and Compound I is reduced to Compound II and Reaction (10), in which Compound II is reduced to native MPO, completing the catalytic... 

The result of this change in mechanism is that the major products at high temperatures are olefins and hydrogen peroxide and their secondary decomposition products, which of course include water. The relatively unstable alkyl hydroperoxide produced by the low temperature chain is replaced by the much more stable hydrogen peroxide. The result is that the secondary initiation, responsible for the cool flames, is replaced by a much slower initiation—the second-order decomposition of hydrogen peroxide (Reaction 6). 

Richman, J. E. Chang, Y.-C. Kambourakis, S. Draths, K. M. Almy, E. Snell, K. D. Stras-burg, G. M. Frost, J. W. Reaction of 3-dehy-droshikimic acid with molecular oxygen and hydrogen peroxide products, mechanism, and associated antioxidant activity. /. Am. Chem. Soc. 1996, 3 38, 11587-11591. 

Chloride ions are consumers of OH radicals whereas active chlorine may consume OH radicals, ozone and hydrogen peroxide. The mechanism of the peroxide reaction with active chlorine depends on the pH as summarised elsewhere (Blum 1989). Summary expressions are ... 

Wiberg KB. The mechanisms of hydrogen peroxide reactions. I. The conversion of benzonitrile to benzamide. J Am Chem Soc 1953 75 3961-4. 

Peroxidase reacts by mechanisms similar to catalase, but the reaction catalyzed is the oxidation of a wide variety of organic and inorganic substrates by hydrogen peroxide (Reaction 5.83). 

Theorell (79) has suggested an alternative mechanism based on the combination of substrate and acceptor molecules with two hematin groups. Chance (78) has pointed out that this mechanism cannot apply to the primary alkyl hydroperoxide complexes reacting with an alcohol or hydrogen peroxide (as in reactions ii and iii) because all hematin groups are attached to hydroperoxide molecules in these complexes however, it is applicable to the catalytic decomposition of hydrogen peroxide. The mechanism may be represented ... 

Hydrogen peroxide reactions, free radical mechanism in, 4, 343... 

The compleu ly different redox properties of reactive oxygen species in aprotic media or membranes lead to other routes of interaction of superoxide with hydrogen peroxide . Another mechanism independent to the Haber-Weiss reaction was found. In addition, there are stoichiometrically acting molecules like ascorbate or NADPH, which were thought to be involved in the generation of hydroxyl radicals via the equation... 

The reduction of hydrogen peroxide (reaction 14 or 15) may start with either an electrochemical step [10,55,56] or a chemical step [23, 24,57—59]. Molecular oxygen should be formed if the Haber-Grinberg mechanism [60] of the catalytic decomposition of H2O2 on platinum... 

The mechanism of peroxidation involves the reduction of Cu(II)-SODl by hydrogen peroxide (reaction 1) followed by the reaction with another molecule of peroxide to produce a species capable of transferring the elements of a hy oxyl radical, OH, to an exogenous substrate (reaction 2). 

In a 500 ml. three-necked flask, equipped with a mechanical stirrer, thermometer and dropping funnel, place 300 ml. of 88-90 per cent, formic acid and add 70 ml. of 30 per cent, hydrogen peroxide. Then introduce slowly 41 g. (51 ml.) of freshly distilled cyclohexene (Section 111,12) over a period of 20-30 minutes maintain the temperature of the reaction mixture between 40° and 45° by cooling with an ice bath and controlling the rate of addition. Keep the reaction mixture at 40° for 1 hour after all the cyclohexene has been added and then allow to stand overnight at room temperature. Remove most of the formic acid and water by distillation from a water bath under reduced pressure. Add an ice-cold solution of 40 g. of sodium hydroxide in 75 ml. of water in small portions to the residual mixture of the diol and its formate take care that the tempera... 

The mechanism of this reaction involves an activation of the ammonia and hydrogen peroxide because these compounds do not themselves react (118—121). It appears that acetamide functions as an oxygen transfer agent, possibly as the iminoperacetic acid (41) which then oxidizes the transient Schiff base formed between MEK and ammonia (40) to give the oxaziridine (42), with regeneration of acetamide ... 

Hydrogen peroxide may react directiy or after it has first ionized or dissociated into free radicals. Often, the reaction mechanism is extremely complex and may involve catalysis or be dependent on the environment. Enhancement of the relatively mild oxidizing action of hydrogen peroxide is accompHshed in the presence of certain metal catalysts (4). The redox system Fe(II)—Fe(III) is the most widely used catalyst, which, in combination with hydrogen peroxide, is known as Fenton s reagent (5). 

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). 

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