Kinetic and product studies of the reactions of NO3 with a series of unsaturated organic compounds

Yangang Ren (1) , Max Mcgillen (1, 2) , Ibrahim Ouchen (3) , Véronique Daële (1) , Abdelwahid S Mellouki (1)

1 ICARE - Institut de Combustion, Aérothermique, Réactivité et Environnement
2 LE STUDIUM Loire Valley Institute for Advanced Studies
3 UM5 - Université Mohammed V de Rabat [Agdal]

Rate coefficients for the reaction of NO3 radicals with 6 unsaturated volatile organic compounds (VOCs) in a 7300 L simulation chamber at ambient temperature and pressure have been determined by the relative rate method. The resulting rate coefficients were determined for isoprene, 2-carene, 3-carene, methyl vinyl ketone (MVK), methacrolein (MACR) and crotonaldehyde (CA), as (6.6 ± 0.8) × 10−13, (1.8 ± 0.6) × 10−11, (8.7 ± 0.5) × 10−12, (1.24 ± 1.04) × 10−16, (3.3 ± 0.9) × 10−15 and (5.7 ± 1.2) × 10−15 cm3/(molecule•sec), respectively. The experiments indicate that NO3 radical reactions with all the studied unsaturated VOCs proceed through addition to the olefinic bond, however, it indicates that the introduction of a carbonyl group into unsaturated VOCs can deactivate the neighboring olefinic bond towards reaction with the NO3 radical, which is to be expected since the presence of these electron-withdrawing substituents will reduce the electron density in the π orbitals of the alkenes, and will therefore reduce the rate coefficient of these electrophilic addition reactions. In addition, we investigated the product formation from the reactions of 2-carene and 3-carene with the NO3 radical. Qualitative identification of an epoxide (C10H16OH+), caronaldehyde (C10H16O2H+) and nitrooxy-ketone (C10H16O4NH+) was achieved using a proton transfer reaction time-of-flight mass spectrometer (PTR-TOF-MS) and a reaction mechanism is proposed.

Mots clés: Rate coefficient; NO3 radical; Products; Volatile organic compounds (VOCs)

Domaines: Autre; Sciences de l'environnement

Yangang Ren, Max Mcgillen, Ibrahim Ouchen, Véronique Daële, Abdelwahid S Mellouki. Kinetic and product studies of the reactions of NO3 with a series of unsaturated organic compounds. Journal of Environmental Sciences, 2020, 95, pp.111-120. ⟨10.1016/j.jes.2020.03.022⟩. ⟨hal-02909398⟩