Gas-phase reactions of nopinone, 3-isopropenyl-6-oxo-heptanal, and 5-methyl-5-vinyltetrahydrofuran-2-ol with OH, NO3, and ozone

In the troposphere, alpha-pinene, beta-pinene, limonene, and linalool are mainly oxidized to pinonaldehyde, nopinone, 3-isopropenyl-6-oxoheptanal (IPOH), and 5-methyl-5-vinyltetrahydrofuran-2-ol ( MVT), respectively. The rate constant of the reactions of nopinone, IPOH, and MVT with OH, NO3, and O-3 were determined by long path FT-IR spectroscopy, and the oxidation products from the reactions between the OH radical and pinonaldehyde, nopinone, IPOH, and MVT were investigated using GC-MS and HPLC. The reaction rate constants (k) for the reactions have been determined at 740 +/- 5 Torr and 298 +/- 5 K, and a number of reaction products were identified. The rate constants obtained for the reactions with nopinone were k(OH) = (1.7 +/- 0.2) x 10(-11), k(NO3) < 2 x 10(-15) and k(O3) < 5 x 10(-21); far the reactions with IPOH were k(OH) = (1.1 +/- 0.3) x 10(-10), k(NO3) = (2.6 +/- 0.8) x 10(-13), and k(O3) = (8.3 +/- 2.2) x 10(-18); and for the reactions with MVT were k(OH) = (7.4 +/- 0.9) x 10(-11), k(NO3) = (2.0 +/- 0.9) x 10(-14) and k(O3) = (3.8 +/- 0.8) x 10(-18) (all units are in cm(3) molecule(-1) s(-1), and uncertainties are given as two sigma on the experimental data). From the results obtained in this investigation and previous studies, it was concluded that a typical atmospheric lifetime with respect to chemical reactions was only a few hours for pinonaldehyde, IPOH, and MVT but was much longer for nopinone with a lifetime of about 10 h.