26397-33-1Relevant academic research and scientific papers
Kinetics of the cross reactions of CH3O2 and C2H5O2 radicals with selected peroxy radicals
Villenave, Eric,Lesclaux, Robert
, p. 14372 - 14382 (2007/10/03)
The kinetics of the reactions of selected peroxy radicals (RO2) with CH3O2 and with C2H5O2 have been investigated using two techniques: excimer-laser photolysis and conventional flash photolysis, both coupled with UV absorption spectrometry. Radicals were generated either by photolysis of molecular chlorine in the presence of suitable hydrocarbons or by photolysis of the appropriate alkyl chloride. All such cross-reaction kinetics were investigated at 760 Torr total pressure and room temperature except for the reaction of the allylperoxy radical with CH3O2, for which the rate constant was determined between 291 and 423 K, resulting in the following rate expression: k15 = (2.8 ± 0.7) × 10-13 exp[(515 ± 75)/T] cm3 molecule-1 s-1. Values of (2.0 ± 0.5) × 10-13, (1.5 ± 0.5) × 10-12, (9.0 ± 0.15) × 10-14, -12, (2.5 ± 0.5) × 10-12, and (8.2 ± 0.6) × 10-12 (units of cm3 molecule-1 s-1) have been obtained for the reactions of CH3O2 radicals with C2H5O2, neo-C5H11O2, c-C6H11O2, C6H5CH2O2, CH2ClO2, and CH3C(O)O2, respectively, and (1.0 ± 0.3) × 10-12, (5.6 ± 0.8) × 10-13, (4.0 ± 0.2) × 10-14, and (1.0 ± 0.3) × 10-11 (units of cm3 molecule-1 s-1) for the reactions of C2H5O2 with CH2=CHCH2O2, neo-C5H11O2, c-C6H11O2, and CH3C(O)O2 radicals, respectively. These rate constants were obtained by numerical simulations of the complete reaction mechanisms, which were deduced from the known mechanisms of the corresponding peroxy radical self-reactions. A systematic analysis of propagation of errors was carried out for each reaction to quantify the sensitivity of the cross-reaction rate constant to the parameters used in kinetic simulations. The rate constant for a given cross reaction is generally found to be between the rate constants for the self-reactions of RO2 and CH3O2 (or C2H5O2). However, when the RO2 self-reaction is fast, the cross reaction with CH3O2 (or C2H5O2) is also fast, with similar rate constants for both reactions, suggesting that these particular peroxy radical cross reactions can play a significant role in the chemistry of hydrocarbon oxidation processes in the troposphere and in low-temperature combustion. Relationships between cross-reaction and self-reaction rate constants are suggested.
Kinetics of free radicals produced by infrared multiphoton-induced decompositions. 1. Reactions of allyl radicals with nitrogen dioxide and bromine
Slagle, Irene R.,Yamada, Fumiaki,Gutman, David
, p. 149 - 153 (2007/10/02)
A new versatile technique to study quantitatively the gaseous reactions of polyatomic free radicals is described in detail. Free radicals are generated homogeneously in a tubular reactor by the infrared multiphoton-induced decomposition (MPD) of suitable radical precursors. The concentrations of reactants and products (both stable and labile) are monitored by using photoionization mass spectrometry. Reactions of the allyl radical, generated by the MPD of allyl bromide, with nitrogen dioxide and bromine have been studied at 300 K. The measured rate constants are 3.9(±0.8) × 10-11 cm3 s-1 for the C3H5 + NO2 reaction and 9.0(±1.8) × 10-12 cm3 s-1 for the C3H5 + Br2 reaction. The potential of the experimental facility for other kinds of studies is discussed.
