- Products and Mechanisms of the Gas-Phase reactions between NO3 and a Series of Alkenes
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Products and mechanisms for the gas-phase reactions of NO3 radicals with a series of alkenes in air have been studied.The experiments with propene, isobutene, trans- and cis-2-butene, 2-methyl-2-butene, and 2,3-dimethyl-2-butene were carried out at 295 +/- 2 K and 740 +/- 5 Torr in a 480-L Teflon-coated reaction chamber where NO3 was generated by the thermal dissociation of N2O5.Reactants and products were observed to produce nitroxy-nitroperoxy intermediates that decayed with formation of carbonyl, nitroxycarbonyl, nitroxy alcohol, and dinitrate species.The product distribution was found to be dependent on the alkyl substitution pattern around the double bond.Evidence was also found of a reaction between NO3 and organic peroxy radicals with a rate constant measured in the case of 2,3-dimethyl-2-nitroxy-3-peroxybutane radical to be of the order of 5 * 10-12 cm3 molecule-1 s-1.
- Hjorth, J.,Lohse, C.,Nielsen, C. J.,Skov, H.,Restelli, G.
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- Kinetics and Products of the Reactions of NO3 with Monoalkenes, Dialkenes, and Monoterpenes
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Rate constants for the reactions of NO3 with a number of aliphatic mono- and dialkenes and monoterpenes have been determined in a 420 l reaction chamber at 1-bar total pressure of synthetic air by 298 K with a relative kinetic method.The products of these reactions have been investigated also at 1-bar total pressure of synthetic air with in situ FT-IR spectrometry and gas chromatography.In all cases, the initial formation of thermally unstable nitrooxy-peroxynitrate-type compounds containing the difunctional group -CH(OONO2)-CH(ONO2)- has been observed.The experimental results are consistent with a mechanism involving the formation of nitrooxy-alkoxy radicals, -CH(O)-CH(ONO2)-, via the self-reaction of the nitrooxy-peroxy radicals.The further reactions of the nitrooxy-alkoxy radicals then determine the final products.The main reaction pathways are (i) reaction with O2 to form nitrooxy-aldehydes or -ketones and HO2 and (II) thermal decomposition forming aldehydes/ketones and NO2.The mechanisms leading to the final products are discussed, and their possible relevance for the chemistry in the troposphere is considered.
- Barnes, Ian,Bastian, Volker,Becker, Karl H.,Tong, Zhu
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p. 2413 - 2419
(2007/10/02)
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