Ethoxy radicals, decomposition

The thermal unimolecular decomposition of ethoxy radicals (C2H5O ) was investigated at different temperatures and pressures. Under these conditions the fi-C—C scission CH3CH2O -f M CH2O - - CH3 - - M is the dominant decomposition channel. Excellent agreement between the experimental and calculated rate constants has been found. ... 

Various compounds were shown to sensitize the photochemical decomposition of pyridinium salts. Photolysis of pyridinium salts in the presence of sensitizers such as anthracene, perylene and phenothiazine proceeds by an electron transfer from the excited state sensitizer to the pyridinium salt. Thus, a sensitizer radical cation and pyridinyl radical are formed as shown for the case of anthracene in Scheme 15. The latter rapidly decomposes to give pyridine and an ethoxy radical. Evidence for the proposed mechanism was obtained by observation of the absorption spectra of relevant radical cations upon laser flash photolysis of methylene chloride solutions containing sensitizers and pyridinium salt [64]. Moreover, estimates of the free energy change by the Rehm-Weller equation [65] give highly favorable values for anthracene, perylene, phenothiazine and thioxanthone sensitized systems, whilst benzophenone and acetophenone seemed not to be suitable sensitizers (Table 5). The failure of the polymerization experiments sensitized by benzophenone and acetophenone in the absence of a hydrogen donor is consistent with the proposed electron transfer mechanism. 

All the major products of both the slow decomposition and explosive reaction can be accounted for qualitatively by reactions of the ethoxy radicals formed in the initial step which involves fission of the 0—0 bond. The reaction scheme is... 

The thermal decomposition of alkyl nitrates has received continuous attention over a number of years. The introduction of improved techniques has required the periodic re-evaluation of data on these very complex reactions . The substrate of choice has been ethyl nitrate. Early studies on the thermal decomposition suggested that the reaction became complex after the initial fission into ethoxy radicals and nitrogen dioxide . 

Tajima, Okada and coworkers reported the unimolecular metastable decompositions of aUcoxysilanes in a number of recent studies - . These authors found significant differences in the ion fragmentation characteristics between the silanes and their carbon analogues. Thus, for example, the principal fragmentation process of ionized diethoxy-dimethylsilane was found to correspond to a consecutive loss of ethylene and aldehyde molecules from the siUcenium ion formed by loss of an ethoxy radical. In contrast, the carbon analogue acetone diethyl acetal does not exhibit a significant loss of aldehyde molecules in its metastable ion mass spectrum. 

In the course of study of the reaction of NO with aromatic amines, the effect of solvents on the reaction mechanism has been established. NO reacts in ethereal solvents (tetrahydrofuran (THF), dioxane, ethoxy ethane (EtOEt), dimethylether (DME)) or chloroform to give deamination products [33]. This solvent effect was explained by the competitive decomposition of diazonium ions via accepting an electron from NO to give the phenyl radical, and hydrogen (H)-atom abstraction from the solvent leads to the deamination product ... 

Dames EE. Master equation modeling of the unimolecular decompositions of a-hydroxyethyl (CH3CHOH) and ethoxy (CH3CH2O) Radicals. Int J Chem Kinet. March 2014 46 176-188. 

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