13799-69-4Relevant articles and documents
Relative rate study of the reactions of acetylperoxy radicals with NO and NO2: peroxyacetyl nitrate formation under laboratory conditions related to the troposphere
Seefeld,Kinnison,Kerr
, p. 55 - 59 (1997)
A relative rate study has been performed on the reactions CH3C(O)O2· + NO2 + M → CH3C(O)O2NO2 + M (1) and CH3C(O)O2· + NO → CH3· + CO2 + NO2 (2) in an atmospheric flow system in which the relative yields of CH3C(O)O2NO2 (PAN) have been measured as a function of the ratio of reactants [NO]/[NO2]. Over the temperature range 247-298 K, at a total pressure of approx.1 atm, the ratio was independent of temperature, k1/k2 = 0.41 ± 0.03, where the error limits are 2σ. The results are discussed with reference to other relative rate measurements of k1/k2 and to absolute measurements of k1 and k2. The atmospheric implications of the ratio k1/k2 in relation to PAN are briefly considered.
A reinvestigation of the kinetics and the mechanism of the CH 3C(O)O2 + HO2 reaction using both experimental and theoretical approaches
Le Crane, Jean-Paul,Rayez, Marie-Therese,Rayez, Jean-Claude,Villenave, Eric
, p. 2163 - 2171 (2006)
The kinetics and the mechanism of the reaction CH3C(O)O 2 + HO2 were reinvestigated at room temperature using two complementary approaches: one experimental, using flash photolysis/UV absorption technique and one theoretical, with quantum chemistry calculations performed using the density functional theory (DFT) method with the three-parameter hybrid functional B3LYP associated with the 6-31G(d,p) basis set. According to a recent paper reported by Hasson et al., [J. Phys. Chem., 2004, 108, 5979-5989] this reaction may proceed by three different channels: CH3C(O)O 2 + HO2 → CH3C(O)OOH + O2 (1a); CH3C(O)O2 + HO2 → CH3C(O)OH + O3 (1b); CH3C(O)O2 + HO2 → CH3C(O)O + OH + O2 (1c). In experiments, CH 3C(O)O2 and HO2 radicals were generated using Cl-initiated oxidation of acetaldehyde and methanol, respectively, in the presence of oxygen. The addition of amounts of benzene in the system, forming hydroxycyclohexadienyl radicals in the presence of OH, allowed us to answer that channel (1c) is 1 of reaction (1) has been finally measured at (1.50 ± 0.08) × 10-11 cm 3 molecule-1 s-1 at 298 K, after having considered the combination of all the possible values for the branching ratios k1a/k1, k1b/k1, k 1c/k1 and has been compared to previous measurements. The branching ratio k1b/k1, determined by measuring ozone in situ, was found to be equal to (20 ± 1)%, a value consistent with the previous values reported in the literature. DFT calculations show that channel (1c) is also of minor importance: it was deduced unambiguously that the formation of CH3C(O)OOH + O2 (X 3Σ-g) is the dominant product channel, followed by the second channel (1b) leading to CH3C(O)OH and singlet O3 and, much less importantly, channel (1c) which corresponds to OH formation. These conclusions give a reliable explanation of the experimental observations of this work. In conclusion, the present study demonstrates that the CH3C(O)O 2 + HO2 is still predominantly a radical chain termination reaction in the tropospheric ozone chain formation processes. the Owner Societies 2006.
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.
