Organic reaction mechanism methyl radical

Of definite interest are reactions of iron porphyrins containing methyl radicals, because the question is in the mechanism of the toxic impact of the haloalkanes on living organisms (Figure 7.3) [68], They are formed by the following reaction ... 

On the other hand, the indirect type of ozonation is due to the reactions of free radical species, especially the hydroxyl radical, with the organic matter present in water. These free radicals come from reaction mechanisms of ozone decomposition in water that can be initiated by the hydroxyl ion or, to be more precise, by the hydroperoxide ion as shown in reactions (4) and (5). Ozone reacts very selectively through direct reactions with compounds with specific functional groups in their molecules. Examples are unsaturated and aromatic hydrocarbons with substituents such as hydroxyl, methyl, amine groups, etc. [45,46],... 

Methylcorrinoids are competent for the efficient methylation of alkyl radicals. Thermolysis of 2 -bis(ethoxycarbonyl)propylcobalamin and methylcobalamin at 70 °C led to formation of cob(II)alamin and the organic products 2-ethyl-2-methylmalonic acid diethyl ester and 2,2-dimethylmalonic acid diethyl ester. The former product was generated with quantitative deuterium incorporation from CDsCobjllljalamin. The proposed mechanism involves homolytic substitution on methylcob(III)alamin by the 2 -bis(ethoxycarbonyl)propyl radical, resulting in net methyl-radical abstraction, a process calculated to be highly exothermic (A7/ -201 kJmoK ). The stereochemical course of the reaction should result in net inversion at the methyl carbon, although this has not been demonstrated. The reaction may serve as a precedent for several biosynthetic methylations, such as the antibiotic thienamycin synthesis. ... 

Atmospheric reactions of MTBE are often initiated by hydroxyl radicals that abstract hydrogen from the methyl groups to form water and organic rascals. There are various kinds of models and mechanisms postulated. The following are two possible initial reactions. For hydrogen radical abstraction at the methoxy end ... 

Chemical initiation generates organic radicals, usually by decomposition of a2o (11) or peroxide compounds (12), to form radicals which then react with chlorine to initiate the radical-chain chlorination reaction (see Initiators). Chlorination of methane yields all four possible chlorinated derivatives methyl chloride, methylene chloride, chloroform, and carbon tetrachloride (13). The reaction proceeds by a radical-chain mechanism, as shown in equations 1 through. Chain initiation... 

There has been interest in the photolysis of organic hypochlorites as a source of alkoxyl radicals and as useful intermediates in synthetic work . The hypochlorites show absorption at A 2500-2600 A and at 3000-3200 A. In their rearrangement reactions it is probably the longer wavelength region which is of importance. t-Butyl hypochlorite decomposes in sunlight to methyl chloride and acetone, and a chain mechanism has been proposed for the decomposition... 

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