Gas-Phase Reactions of Nopinone, 3-Isopropenyl-6-oxo-heptanal, and 5-Methyl-5-vinyltetrahydrofuran-2-ol with OH, NO3, and Ozone

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In the troposphere, α-pinene, β-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, NO 3, 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) × 10 - 11, k NO 3 < 2 × 10 - 15, and k O 3 < 5 × 10 - 21; for the reactions with IPOH were k OH = (1.1 ± 0.3) × 10 - 10, k NO 3 = (2.6 ± 0.8) × 10 - 13, and k O 3 = (8.3 ± 2.2) × 10 - 18; and for the reactions with MVT were k OH = (7.4 ± 0.9) × 10 - 11, k NO 3 = (2.0 ± 0.9) × 10 - 14, and k O 3 = (3.8 ± 0.8) × 10 - 18 (all units are in cm 3 molecule - 1 s - 1, and uncertainties are given as two σ 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.