| Title: | Hydroxyl radical regeneration in the photochemical oxidation of glyoxal: kinetics and mechanism of the HC(O)CO + O(2) reaction |
| Address: | "Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville 3010, Victoria, Australia. gdasilva@unimelb.edu.au" |
| ISSN/ISBN: | 1463-9084 (Electronic) 1463-9076 (Linking) |
| Abstract: | "Glyoxal, HC(O)CHO, is an important trace component of the Earth's atmosphere, formed in biomass burning and in the photooxidation of volatile organic compounds (VOCs) like isoprene and aromatic hydrocarbons. The HC(O)CO free radical is the primary product of the glyoxal + OH reaction, and this study uses computational chemistry to show that the HC(O)CO radical can react with O(2) to regenerate the hydroxyl radical (OH) in the atmosphere. Master equation simulations indicate that the HC(O)C(O)O(2) peroxy radical adduct proceeds directly to CO(2) + CO + OH in a chemically activated mechanism, with minor collisional deactivation of the relatively unstable HC(O)C(O)O(2) peroxy radical. The reaction of HC(O)CO with O(2) is found to be competitive with thermal decomposition to HCO + CO at tropospheric temperatures and pressures, accounting for ca. 40% or more of the total yield. The present process provides a new mechanism for OH regeneration in the troposphere, which involves the decomposition of unstable alpha-formylperoxy radicals" |
| Keywords: | Glyoxal/*chemistry Hydroxyl Radical/*chemistry Kinetics Oxidation-Reduction Oxygen/*chemistry Photolysis; |
| Notes: | "Medlineda Silva, Gabriel eng England 2010/04/29 Phys Chem Chem Phys. 2010 Jul 7; 12(25):6698-705. doi: 10.1039/b927176g. Epub 2010 Apr 27" |
