Direct kinetics study of CH2OO + methyl vinyl ketone and CH2OO + methacrolein reactions and an upper limit determination for CH2OO + CO reaction

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Eskola , A J , Döntgen , M , Rotavera , B , Caravan , R L , Welz , O , Savee , J D , Osborn , D L , Shallcross , D E , Percival , C J & Taatjes , C A 2018 , ' Direct kinetics study of CH2OO + methyl vinyl ketone and CH2OO + methacrolein reactions and an upper limit determination for CH2OO + CO reaction ' , Physical Chemistry Chemical Physics , vol. 20 , no. 29 , pp. 19373-19381 . https://doi.org/10.1039/c8cp03606c

Title: Direct kinetics study of CH2OO + methyl vinyl ketone and CH2OO + methacrolein reactions and an upper limit determination for CH2OO + CO reaction
Author: Eskola, Arkke J.; Döntgen, Malte; Rotavera, Brandon; Caravan, Rebecca L.; Welz, Oliver; Savee, John D.; Osborn, David L.; Shallcross, Dudley E.; Percival, Carl J.; Taatjes, Craig A.
Contributor: University of Helsinki, Department of Chemistry
University of Helsinki, Department of Chemistry
Date: 2018-08-07
Language: eng
Number of pages: 9
Belongs to series: Physical Chemistry Chemical Physics
ISSN: 1463-9076
URI: http://hdl.handle.net/10138/307303
Abstract: Methyl vinyl ketone (MVK) and methacrolein (MACR) are important intermediate products in atmospheric degradation of volatile organic compounds, especially of isoprene. This work investigates the reactions of the smallest Criegee intermediate, CH2OO, with its co-products from isoprene ozonolysis, MVK and MACR, using multiplexed photoionization mass spectrometry (MPIMS), with either tunable synchrotron radiation from the Advanced Light Source or Lyman-alpha (10.2 eV) radiation for photoionization. CH2OO was produced via pulsed laser photolysis of CH(2)l(2) in the presence of excess O-2. Time-resolved measurements of reactant disappearance and of product formation were performed to monitor reaction progress; first order rate coefficients were obtained from exponential fits to the CH2OO decays. The bimolecular reaction rate coefficients at 300 K and 4 Torr are k(CH2OO + MVK) = (5.0 +/- 0.4) x 10(-13) cm(3) s(-1) and k(CH2OO + MACR) = (4.4 +/- 1.0) x 10(-13) cm(3) s(-1), where the stated +/- 2 sigma uncertainties are statistical uncertainties. Adduct formation is observed for both reactions and is attributed to the formation of a secondary ozonides (1,2,4-trioxolanes), supported by master equation calculations of the kinetics and the agreement between measured and calculated adiabatic ionization energies. Kinetics measurements were also performed for a possible bimolecular CH2OO + CO reaction and for the reaction of CH2OO with CF3CHCH2 at 300 K and 4 Torr. For CH2OO + CO, no reaction is observed and an upper limit is determined: k(CH2OO + CO) <2 x 10(-16) cm(3) s(-1). For CH2OO + CF3CHCH2, an upper limit of k(CH2OO + CF3CHCH2) <2 x 10(-14) cm(3) s(-1) is obtained.
Subject: CRIEGEE INTERMEDIATE CH2OO
GAS-PHASE OZONOLYSIS
PHOTOIONIZATION MASS-SPECTROMETRY
METHYL VINYL KETONE
SIMPLE ALKENES
REACTION-MECHANISM
CHEMICAL-KINETICS
ISOPRENE
MOLECULES
ETHYLENE
116 Chemical sciences
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