Mechanism of oxidation reactions

Schroder D, Schwarz H (2007) Intrinsic Mechanisms of Oxidation Reactions as Revealed by Gas-Phase Experiments. 22 1-15... 

Intrinsic Mechanisms of Oxidation Reactions as Revealed by Gas-Phase Experiments... 

In several recent studies an assumption is made concerning the homogeneous-heterogeneous mechanisms of oxidation reactions as a reason for critical effects, in particular in the oxidation of cyclohexane over zeolites [131] and of CO over Pd [132-134] and V [135] catalysts. Berman and Elinek [131] have established in their experiments that cyclohexane oxidation over zeolites follows a mixed homogeneous-heterogeneous mechanism. Studies of the mathematical reaction model written down in accordance with the law of mass action showed that the system can have from one to three steady states. When the steady state is unique, there exists a region of parameters... 

This is the only mechanism from mechanisms (7) in which the total kinetic order with respect to intermediates for every step is no greater than two. Scheme (8) enters as a component into the detailed mechanisms of oxidation reactions over metals. In particular, many researchers describe CO oxidation over platinum metals by the type (8) mechanism. 

Because of their importance in the mechanism of oxidation reactions, much attention has been paid to the kinds of oxygen species present on the surface of these catalysts. A general review concerning oxygen in catalysis by transition metal oxides has recently been presented by Bielanski and Haber.5 In this section the most important results of the main methods of investigation are reviewed. 

Meunier B, SP de Visser, S Shaik (2004) Mechanism of oxidation reactions catalyzed by cytochrome P450 enzymes. Chem. Rev. 104 (9) 3947-3980... 

The oxides of transition metals have found a wide use as active components of oxidation catalysts. For the elucidation of the mechanism of oxidation reactions related to the transition of oxygen between molecules of reactants, it is very important to establish whether catalyst oxygen participates directly in these transitions. 

Structural information about these nonradical products would afford important contributions to the knowledge of the mechanism of oxidative reactions. 

Our principal concern is to utilize both kinetics and product formation as diagnostic tools for elucidating the detailed mechanisms of oxidation reactions in terms of elementary steps, rate coefficients, thermochemistry and structure—reactivity relationships. Accordingly, our emphasis throughout the chapter will be on these relationships, exemplified by reactions of simple molecules and the way in which they may be used to interpret and predict the rates and products of oxidation reactions involving more complex molecules or extreme conditions. ... 

This reaction processes can be explained by the schematic illustration of the oxidation mechanism shown in Figure 4.14. From the above analyses, the mechanism of oxidation reaction for the P-SiAlONs was a diffusion-controlled process and could be described as the following steps, which are similar to the oxidation... 

In cases where the true oxidant is a high valent metal species, various spin states may be accessible (35). This is one aspect of the mechanism of oxidation reactions catalyzed by high valent metal complexes that may prove to be of great general significance. This issue has been raised, for example, in connection with photosynthetic water oxidation, where a high spin oxyl of type Mn(IV)—O has been proposed as the likely active form, and not the Mn(V)=0 0x0 previously considered (36). 

In conclusion, our studies of the electrochemistry of some relevant antioxidants in different solvents and determination of their diffusion coefficients have shown that the electrochemical behaviour of the antioxidants is determined predominantly by the hydrophilic/hydrophobic interactions of the hydrocarbon side-chain and the electrostatic interactions of the antioxidant with the surfactant. The strong association of the antioxidant molecules with the SDS micelles results in the significant lowering of its diffusion coefficient and may even change the mechanism of oxidation reaction. 

Manganese dioxide is the classic oxidizing agent used in organic chemistry. For alcohols, the mechanism of oxidation reaction is [48]... 

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