Master equation studies on unimolecular processes in the ozonolysis of isoprene Hyun Kyung Lee, Pitchaya Chantanapongvanij and Thomas A. Stephenson Department of Chemistry & Biochemistry, Swarthmore College, USA The ozonolysis of isoprene (2-methyl-1,3-butadiene) is a critical reaction in the troposphere. The products of this reaction have been implicated in important pathways such as the production of OH radicals during the daytime and nighttime, and as precursors to the production of organic aerosols. The formation of Criegee intermediates – carbonyl oxide compounds – are a key step in the ozonolysis of all alkenes, including isoprene. We report on our computational and modeling studies of the kinetics of the formation and decomposition of one of the Criegee intermediates resulting from the ozonolysis of isoprene, methacrolein (MACR) oxide. Our approach combines electronic structure calculations and master-equation kinetic modeling to yield microcanonical and thermal rates of unimolecular decay. For MACR oxide, rapid isomerization among a subset of conformers competes with unimolecular decay to form dioxirane and dioxole species. The pressure and temperature dependence of these reactions have been examined; the atmospheric implications of these data will be discussed.
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© The Author(s), 2022
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