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Kinetics and Mechanistic Study for Gas Phase Tropospheric Photo-oxidation Reactions of 2,2,2-Trifluoroethyl Methacrylate with OH Radicals and Cl Atoms: An Experimental and Computational Approach
Avinash Kumar,
Published in American Chemical Society
2019
PMID: 31766849
Abstract
The photo-oxidation reactions of 2,2,2-trifluoroethyl methacrylate (TFEMA) initiated by OH radicals and Cl atoms were investigated via experimental as well as computational methodologies. The rate coefficients for these reactions were investigated using the relative rate technique (RR) at temperatures between 268 and 363 K. The rate coefficients for the reaction of OH radicals with TFEMA were measured with reference to diethyl ether and propylene. Propane and propylene were used in the kinetic measurements as reference compounds. At 298 K, experimentally obtained rate coefficients for the reaction of TFEMA with OH radicals and Cl atoms are kTFEMA+OHexp-298K = (2.81 ± 0.54) × 10-11 and kTFEMA+Clexp-298K = (1.91 ± 0.44) × 10-10 cm3 molecule-1 s-1, respectively. The Arrhenius expression obtained for the respective reactions are kTFEMA+OHexp-(268-363K) = (7.32 ± 0.62) × 10-12 exp[(400 ± 53) and kTFEMA+Clexp-(268-363K) = (4.10 ± 0.78) × 10-12 exp[(1228 ± 115)/T]. To further complement our experimental findings, rate coefficients were also calculated computationally for the reactions of OH radicals and Cl atoms with TFEMA at CCSD(T)/cc-pVDZ//M062X/6-31+G(d,p) and CCSD(T)/cc-pVDZ//MP2/6-31+G(d,p) levels of theory using canonical variational transition state theory (CVT) with small curvature tunneling (SCT) over the temperature range 200-400 K. Moreover, to analyze the end products formed during the title reactions, qualitative analyses were performed using gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectroscopy (GC-IR) as analytical tools and degradation mechanisms were proposed for the title reactions. Branching ratios, thermochemical parameters of these reactions, and their impact on the troposphere were discussed. © 2019 American Chemical Society.
About the journal
JournalData powered by TypesetJournal of Physical Chemistry A
PublisherData powered by TypesetAmerican Chemical Society
ISSN10895639
Open AccessNo
Concepts (19)
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    Atoms
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    Computation theory
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    Degradation
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    Electronic states
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    Free radicals
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    Gas chromatography
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    Infrared spectroscopy
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    Mass spectrometry
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    Propylene
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    Troposphere
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    Arrhenius expressions
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    CANONICAL VARIATIONAL TRANSITION-STATE THEORIES
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    Computational approach
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    COMPUTATIONAL METHODOLOGY
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    GAS CHROMATOGRAPHY-MASS SPECTROMETRIES (GC-MS)
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    RELATIVE RATE TECHNIQUES
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    SMALL-CURVATURE TUNNELING
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    THERMOCHEMICAL PARAMETERS
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    Chlorine