Thermal secondary reaction definition

The initial decomposition chemistry involves unimolecular reactions. This was the conclusion of the first gas-phase kinetics study [84] and has been repeatedly confirmed by subsequent bulb and shock-tube experiments [85, 86]. That first study used shock heating to induce thermal decomposition [84], The data were interpreted in terms of simple C-N bond fission to give CH2 and N02. A more extensive and definitive shock-tube study was reported by Zhang and Bauer in 1997 [85]. Zhang and Bauer presented a detailed kinetics model based on 99 chemical reactions that reproduced their own data and that of other shock-tube experiments [84, 86]. An interesting conclusion is that about 40% of the nitromethane is lost in secondary reactions. 

The Chemical Reactivity of e aq. The chemical behavior of solvated electrons should be different from that of free thermalized electrons in the same medium. Secondary electrons produced under radio-lytic conditions will thermalize within 10 13 sec., whereas they will not undergo solvation before 10 n sec. (106). Thus, any reaction with electrons of half-life shorter than 10 n sec. will take place with nonsolvated electrons (75). Such a fast reaction will obviously not be affected by the ultimate solvation of the products, since the latter process will be slower than the interaction of the reactant with the thermalized electron. This situation may result in a higher activation energy for these processes compared with a reaction with a solvated electron. No definite experimental evidence has been produced to date for reactions of thermalized nonsolvated electrons, although systems have been investigated under conditions where electrons may be eliminated before solvation (15). 

According to the classical definition. Barton esters are mixed anhydrides of carboxylic acids with thio-hydroxamic acid such as I (Scheme Ij. This class of compound was originally developed to allow the transformation of carboxylic acids to a convenient source of radicals for synthetic application. Even now, they are one of the most important entries to C-radicals. Over time, the scope of the reaction was broadened, allowing the generation of heteroatom-centered radicals, particularly oxyl-, aminyl-, and iminyl radicals of synthetic interest. For these transformations, carbonates and carbamates (II), acetates (IV), and ethers (V) were developed (Scheme 1). Finally, oxalates (III) were used for deoxygenation of secondary and tertiary alcohols. The radical fragmentation reaction of these compounds can be carried out either by irradiation or by thermal activation. Both methods are discussed here briefly. 

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