Oxygen reduction peroxide involvement

Appleby, A. and Savy, M. (1978). Kinetics of Oxygen Reduction Reactions Involving Catalytic Decomposition of Hydrogen Peroxide Application to Porous and Rotating Ring-disk Electrodes, J. Electroanal. Chem., 92, pp. 15-30. 

Other reachons involving oxygen are those reachon steps in oxygen reduction which are of importance in their own right, such as the formation of hydrogen peroxide as a relahvely stable intermediate ... 

The role of oxygen in metabolism involves a paradox. Combustion of food to release and store its energy content requires a stepwise four-electron reduction of oxygen to produce harmless water, carbon dioxide, and ammonia (Figure 10.1). The first electron produces superoxide anion radical, the second produces peroxide anion, the third produces hydroxyl radical, and the fourth produces water. When this process is compartmentalized... 

This second pathway, which is indirect oxygen reduction pathway, is commonly designated as the series pathway. The total number of exchanged electrons (nO involved for catalysts which performs the ORR following the series pathway can vary from two to four depending on the amount of water peroxide present in the reaction products (Eq. 45) ... 

The structure of ophiobolin A (5.137) was established by chemical degradation and by X-ray crystallography of a bromo derivative. The spectroscopic characteristics of ophiobolin A led to the identification of the oxygen functions and the double bonds. The relationship between the aldehyde and the cyclo-pentanone was revealed by the formation of a y-lactone on reduction and partial re-oxidation. A cyclic pyridazine was formed with hydrazine. Tetra-hydro-ophiobolin A formed an unusual cyclic peroxide involving these two groups. Vigorous oxidation of tetrahydro-ophiobolin A afforded a heptanoic acid lactone, which revealed the structure of the side-chain. 

Nowadays, it has been demonstrated that the reaction is indeed structure sensitive with a multielectron transfer process that involves several steps and the possible existence of several adsorption intermediates [93-96]. The main advantage that we have with the new procedures with respect to cleanliness is that we have well-ordered surfaces to study a complex mechanism such as the oxygen electroreduction reaction [96-99]. In aqueous solutions, the four-electron oxygen reduction appears to occur by two overall pathways a direct four-electron reduction and a peroxide pathway. The latter pathway involves hydrogen peroxide as an intermediate and can undergo either further reduction or decomposition in acid solutions to yield water as the final product. This type of generic model of a reaction has been extensively studied since the early 1960s by different authors [100-108]. 

The oxygen reduction reaction can proceed by two pathways in aqueous electrolytes. The first one, the so-called direct pathway, involves releasing four electrons per oxygen molecule to yield HgO. The indirect pathway involves releasing two electrons to yield hydrogen peroxide (HgOg) that in successive steps can produce water. Two further pathways, which are combinations of the above, can be envisaged. The series pathway implies sequential two or... 

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