ISSN:
0538-8066
Keywords:
Chemistry
;
Physical Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Product distributions resulting from the oxidation of toluene in air initiated by chlorine atoms, by toluene photolysis, and by hydroxyl radicals were studied at atmospheric pressure in the absence of nitrogen oxides. In the first case only benzaldehyde and benzylalcohol with a ratio of 7.8 ± 1.7 were observed, from which a branching ratio α = 0.76 ± 0.05 was derived for the radical propagating pathway of the self-reaction of benzylperoxy radicals. In the second and third case the apparent branching ratio decreased to α = 0.56 ± 0.07 and 0.37 ± 0.08, respectively, indicating the occurrence of additional reactions between benzylperoxy and other peroxy radicals. The major ring retaining products resulting from the reaction of OH with toluene were o-cresol, p-cresol. and methyl-p-benzo-quinone (57.9 ± 12.5% reacted carbon, corrected for secondary losses), in addition to 7.7 ± 1.6% benzaldehyde and benzylalcohol arising from methyl hydrogen abstraction. Formaldehyde, acetaldehyde, glyoxal, methylglyoxal, carbon monoxide, and carbon dioxide were observed as ring cleavage products (25.0 ± 7.2%). Except for CO2, which appears to be an important ring cleavage product only under NOχ-free conditions, the distribution of ring cleavage products was similar to that found by Gery et al (1985) in the presence of NOχ. Comparison of experimental data and results from computer simulations show that self-reactions of the hydroxy-methyl-cyclo-hexadienylperoxy radicals are negligible compared to internal rearrangement reactions leading to ring stabilization or ring cleavage. The mechanism of CO2 production appears to require the formation of a Criegee intermediate. © 1996 John Wiley & Sons, Inc.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/kin.1
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