CH3O2 radicals

Methoxy (CH3O ) and methylperoxy (CH3O2 ) radicals have been subjected to substantial study. Zaslonko et al. have reviewed several reactions involving the... 

OH oxidation of DMS is not a nett sink for OH provided the concentration of NO is not too low. Since DMS levels are <0.5 ppb any such perturbation of the OH concentration would be expected to be small. It is further reduced by regeneration of OH following the initial OH/DMS reaction. Regardless of whether addition or abstraction occurs one CH3O2 radical is produced for each OH radical consumed. OH is then regenerated principally by ... 

The comparison of the reaction rates of O3, HO2, and CH3O2 with olefin, paraffin, and NO reveals that the predominant reactions of these reactive species are the oxidations of NO [(VI11-I8), (VIll-21a), and (Vlll-24)]. The major destruction processes of olefin are the reactions with O3 and with OH. (The rate of olefin destruction is proportional to the rate constant times the concentration of the active species.) The destruction process of olefins by HO2 is less important and those by O atoms and CH3O2 radicals are also minor. 

Methyl peroxynitrate, CH3OONO2, thermally dissociates back to the reactants with a lifetime with respect to thermal decomposition of 1 second at room temperature and atmospheric pressure, which increases to 2 days for the temperature and pressure conditions in the upper troposphere (Atkinson et al., 1989 Atkinson, 1990). Methyl peroxynitrate can act as a temporary reservoir of NO2 and CH3O2 radicals in the upper troposphere. 

From an analysis of product ratios they obtained 36/( 35 19) = 0.31, / i9a/ i9b = 8.9, and k-2nlk g = 0.021 AT" -sec. These values can be compared with the respective values of Heicklen and Johnston (1962a), which were 0.14, 9-12, and 0.020 ilf -sec, where the CH3O2 radicals were prepared from the steady-state photolysis of CH3I-O2 mixtures. However, in Heicklen and Johnston s work no direct calibration was made for CH3(X)H. This could account for the factor-of-2 discrepancy in the two reported values for. ... 

Considerable progress has been achieved in the past two years in the determination of rate constants for RO2 + radical reactions. Prior to this, A (H02 + HO2O was known with some precision, and estimates for CH3O2 + radical reactions were available from studies of highly complex photochemical oxidations. ... 

The kinetics of the reaction CH3O2 + NO3 was studied by modulated photolysis spectroscopy [7] and later in a discharge flow reactor combined with molecular beam mass spectrometry [8]. In the latter experiment, the CD3O2 radicals were used instead of CH3O2, and their first order decay monitored in the presence of excess NO3 radicals. It was however observed that the first order decay of the methylperoxy radicals did not extrapolate to a common intercept and that the second order plot showed a large positive intercept. This is caused by the regeneration of CH3O2 radicals via reaction... 

The activities of the Kiel group within LACTOZ concentrated on investigations of secondary atmospheric oxidation processes. The processes selected constitute elementary steps in reaction sequences leading to transformation and degradation of VOCs in the troposphere. The oxidants employed in our studies were the nitrate radical NO3, ozone O3, and in recent experiments the CH3O2 radical. It was the aim of the scientific research to elucidate reaction mechanisms operating in the... 

Laser photofragment emission A novel technique for the study of gas phase reactions of the CH3O2 radical,... 

Spectrum, kinetics and mechanism of CH3O2 radical reactions,... 

The experimental data agree rather well with the simulations as is evident from the above Figures 3 and 4, in which the symbols represent the experimental results while the lines correspond to the simulations. The dependence of ethane and ethylene selectivity on the methane-to-oxygen ratio at a total pressure of 41 kPa and 1044 K as simulated by the described procedure is shown in Figures 6 and 7. From the comparison of experimental and simulated results it turns out that model A is equivalent to model B for temperatures above 1000 K. For lower temperatures model A gives too high C24- selectivities. This indicates that the CH3O2 radical reaction path is important below that temperature. 

Zellner, R., Lorenz, K. Laser photolysis/resraiance fluorescence study of the rate constants for the reactions of hydroxyl radicals with ethene andpropene. J. Phys. Chem. 88,984—989 (1984) Zellner, R., Fritz, B., Lorenz, K. Methoxy foimatirai in the reaction of CH3O2 radicals with NO. J. Atmos. Chem. 4, 241-251 (1986)... 

However, the initial exponential autoacceleration of the reaction does not lead to an explosion, as in most other branched-chain reactions, due to the rapid growth of the rate of quadratic recombination of CH3O2 radicals (negative interaction of chains, nonlinear termination of chains) in reaction (XIII). Therefore, after the initial stage, the process becomes qua-sistationary, remaining so for some time (Fig. 5.1). 

If only CH3O2 radicals are present, so that I r02 = CH3O2, these reactions become ... 

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