Ozonolysis of a series of C7–C9 unsaturated biogenic aldehydes: Reactivity study at atmospheric pressure

Abstract

Rate coefficients for the reactions of O3 with trans-2-heptenal, trans-2-octenal and trans-2-nonenal have been determined at 298 K and (990 ± 10) mbar in an environmental chamber with in situ FTIR spectroscopy. The following rate coefficients in units of kO3 × 1018 (cm3 molecule−1 s−1) were obtained: (2.47 ± 0.73) for trans-2-heptenal, (2.37 ± 0.68) for trans-2-octenal and (2.05 ± 0.20) for trans-2-nonenal. It is shown that rate coefficients for the addition of O3 molecules and OH radicals to the double bond of alkenes and unsaturated and oxygenated volatile organic compounds (OVOCs) at 298 K are related to a good approximation by the expression: log kOH = 0.16 log kO3 − 7.55. Furthermore, a correlation between the reactivity of unsaturated VOCs toward O3 molecules and the energies of the Highest Occupied Molecular Orbit (HOMO) of the unsaturated VOCs is presented and potential atmospheric implications of the results are discussed.