Kinetics of the gas-phase reaction between ozone and three unsaturated oxygenated compounds: Ethyl 3,3-dimethyl acrylate, 2-methyl-2-pentenal and 6-methyl-5-hepten-2-one at atmospheric pressure

• Published in: Atmospheric environment (1994) 2015-05, Vol.109, p.272-278
• Main Authors: Gaona Colmán, Elizabeth, Blanco, María B., Barnes, Ian, Teruel, Mariano A.
• Format: Article
• Language: English
• Subjects: Ozonolysis; Rate coefficients; Relative kinetic method; Tropospheric chemistry; Unsaturated oxygenated compounds
• ISSN: 1352-2310; 1873-2844
• DOI: 10.1016/j.atmosenv.2015.03.011

Rate coefficients for the gas-phase reactions of O3 molecules with three unsaturated oxygenated compounds have been determined using the relative kinetic technique in an environmental chamber with FTIR detection of the reactants at (298 ± 2) K in 760 Torr total pressure of synthetic air. The following rate coefficients (in units of 10−17 cm3 molecule−1 s−1) were determined: ethyl 3,3-dimethyl acrylate (0.82 ± 0.19), 2-methyl-2-pentenal (0.71 ± 0.16) and 6-methyl-5-hepten-2-one (26 ± 7). The different reactivity of the unsaturated oxygenated compounds toward O3 is discussed in terms of their chemical structure. In addition, a correlation between the reactivity of structurally different unsaturated compounds (alkenes and unsaturated oxygenated VOCs, such as ethers, esters, aldehydes, ketones and alcohols) toward O3 molecules and the HOMO (Highest Occupied Molecular Orbital) of the compounds is presented. Using the kinetic parameters determined in this work, residence times of these unsaturated compounds in the atmosphere with respect to reaction with O3 have been calculated. In urban and rural areas the main sink of 6-methyl-5-hepten-2-one is reaction with O3 molecules with a residence time in the order of few minutes. [Display omitted] •Kinetic study of O3 with different unsaturated carbonyl VOCs by in situ FTIR.•Rate coefficients increase with increasing methyl substituent at the double bond of the VOC.•Reactivity towards O3 correlates with HOMO energies of unsaturated compounds.•Short lifetimes, in the order of minutes and hours, for O3 reactions in urban regions.