Oxidation mechanism for

The most widely applied method to prepare sulfones is the oxidation of thioethers. In the course of these oxidations sulfoxides must occur as intermediates. However, since oxidation mechanisms for thioethers and sulfoxides are partly different, these oxidations will be discussed separately. A recently published method337,338 allows oxidation of a... 

The removal of an electron from a carbanion oxidizes it to a free radical and sometimes, in the presence of oxygen, to a peroxide. Organometallic compounds give many radical-like reactions of course, and a possible oxidation mechanism for such compounds is a preliminary dissociation into radicals followed by oxidation of the radicals and the metal. 

FIGURE 4.80 Oxidative mechanisms for the formation of hydroquinone from / -substituted phenols. 

Davis, D. D., and G. Klauber. Atmospheric gas phase oxidation mechanisms for the molecule SO]. Int. J. Chem. Kinet. Symp. 1 (Chemical Kinetics Data for the Lower and Upper Atmosphere) 543-5S6, 1975. 

As concerns the mechanism of anodic oxidation of 5 at sacrificial anodes, it can be noted that the process occurs at potentials close to those of the oxidation of the corresponding diorganomagnesium compounds (1). For example, half-peak potentials for the oxidation of 5b and lb in THF containing 0.25 M TBAP at a lead electrode measured at a scan rate of 0.3 V s are equal to Jip/2 = —1.73 and —1.72 V vs. 0.01 M Ag /Ag, respectively. However, the oxidation mechanism for both compounds is different, as shown... 

A very attractive theory concerning the oxidation mechanism for scheelite-type molybdates containing bismuth is presented by Sleight and Linn [297] and is described below. 

Fig. 13.7 Hierarchical structure and overall interrelationships between oxidation mechanisms for simple hydrocarbon fuels and selected oxygenated fuels ([427], modified).

The oxidation mechanism for hydrogen is well established it was discussed in significant detail in Section 13.2.6.1. Upon initiation, hydrogen is oxidized at high temperatures by the chain-branching sequence ... 

The oxidation mechanism for CO depends on the presence of hydrogen-containing components. In the absence of hydrogen donors, the oxygen atom is the only chain carrier, and CO is oxidized by reaction with O or 02,... 

As the fuel complexity increases, so does the complexity and also the uncertainty of the reaction mechanism. In modeling the oxidation behavior of the large hydrocarbons, the use of semiempirical mechanisms that involve a few overall steps together with a detailed Ci-C2 subset is still a valuable approach [171]. However, for some types of problems, such as prediction of key intermediates or by-products, full mechanisms are preferred. Full oxidation mechanisms for a number of larger hydrocarbons are available in the literature (e.g., [88,92,245,327-330]), but their predictive capabilities must be evaluated carefully for specific applications. 

Formation of Aromatic Compounds A scientific challenge comparable to that of developing oxidation mechanisms for the large hydrocarbon fuels is understanding and describing quantitatively the formation and oxidation of aromatic and polycyclic aromatic compounds (PAH) formed in combustion processes. Aromatic compounds are known to be harmful to the environment, and the emission of these species from a number of combustion systems is a significant concern. Furthermore aromatic species are important pre-... 

Oxidation of Benzene Because of the complexity of the aromatics chemistry, large uncertainties remain in the oxidation mechanisms for even the simplest aromatic species, benzene and toluene [12,113]. The overall oxidation behavior (i.e., the fuel consumption rate) can be calculated with some confidence, but predictions of the concentration of intermediate species may be off by orders of magnitude. 

The nitrogen atoms are then oxidized to NO by reaction with OH (R116), or they can be converted to N2 by reaction with NO (R114b). At lower temperatures the oxidation mechanism for HCN is more complicated, involving formation and consumption of a number of pollutant species including oxicyanides, amines (NH,), and nitrous oxide (N20). 

Write the main elementary reactions in the low-temperature oxidation mechanism for propane (C3H8), based on the general outline for higher hydrocarbons. 

Knoop deduced the j8 oxidation mechanisms for fatty acid degradation. 

It is important to point out that the above treatment is not applicable to different oxidation mechanisms. For example, the kinetic data obtained from dichloroethane oxidation does not give a straight line between log(r0) and log(X), because the oxidation pathway of dichloroethane is different from that in oxidizing chlorinated ethylenes. For example, dichloroethane is one... 

The gas-phase oxidation mechanism for CX3C(0)H and CF3C(0)C1 is shown in Fig. 7. For CX3C(0)H species reaction with OH radicals is import-... 

Dutton, P. L., Moser, C. C., Sled, V. D., Daldal, F., and Ohnishi, T., 1998, A reductant-induced oxidation mechanism for Complex I Biochim. Biophys. Acta 1364 245n257. 

The size effect is probably the most proposed interpretation for the CO oxidation mechanism. For example, this effect on the adsorption of CO was investigated by Rice et al. using in situ infrared reflectance spectroscopy from five different samples of platinum particles with mean diameters of 2.0, 2.5, 3.2, and 3.9 nm, respectively. These authors found that the infrared COl stret-... 

Following the discussion from the preceding section, consideration will be given to the oxidation of ethene and propene (when a radical pool already exists) and, since acetylene is a product of this oxidation process, to acetylene as well. These small olefins and acetylene form in the oxidation of a paraffin or any large olefin. Thus, the detailed oxidation mechanisms for ethane, propane, and other paraffins necessarily include the oxidation steps for the olefins [28]. 

Figure 1 Comparison of the microbial direct versus indirect oxidation mechanism for sulfide (source Sand et al., 2001).

Dodge M. C. (2000) Chemical oxidant mechanisms for air quality modeling critical review. Atmos. Environ. 34, 2103-2130. 

Scheme 20. Possible oxidation mechanisms for the ammoxidation of cyclohexanone to cyclohexanone oxime.

The basic oxidation mechanism for propene and isobutene appears almost unique and apart from OH and HO2 addition involves the formation, through abstraction, of highly inert radicals which are almost completely consumed through radical-radical processes. The tremendous acceleration (over a factor of 100) shown between the initial and maximum rates for both alkenes (Eig. 1.17) can be explained through secondary initiation involving three reactions for each alkene. 

Inspection of most oxidation mechanisms and product profiles shows that aldehydes are primary products, particularly HCHO. Outline oxidation mechanisms for aldehydes have been discussed earlier. Essentially they are good sources of alkyl radicals through the sequence... 

Chaurasia, S.S. and A. Kar. An oxidative mechanism for the inhibition of iodothyronine 5 -monodeiodinase activity by lead nitrate in the fish, Heteropneustes fossilis. Water Air Soil Pollut. Ill 417-423, 1999. 

Jef ies, H.E. M. W. Gery, and W. P. L. Carter Protocol for evaluating oxidant mechanisms for urban and regional models. Report for U.S. Environmental Protection Agency Cooperative Agreement No. 815779, Atmospheric Research and Exposure Assessment Laboratoiy, Research Triangle Park, NC. (1992). 

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