University of Illinois Urbana-Champaign

Mechanism And Kinetics Of The Reaction Of Criegee Intermediate Ch2oo With Acetic Acid Studied With A Step-scan Fourier-transform Ir Spectrometer

Behera, Bedabyas

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WC09_1.pptx
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https://hdl.handle.net/2142/116546

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Title
Mechanism And Kinetics Of The Reaction Of Criegee Intermediate Ch2oo With Acetic Acid Studied With A Step-scan Fourier-transform Ir Spectrometer
Author(s)
Behera, Bedabyas
Contributor(s)
  • Lee, Yuan-Pern
  • Takahashi, Kaito
Issue Date
2022-06-22
Keyword(s)
Electronic structure, potential energy surfaces
Abstract
Acetic acid CH$_{3}$C(O)OH plays an important role in the acidity in the troposphere. The reaction of Criegee intermediate with CH$_{3}$C(O)OH was proposed to be a potential source of secondary organic aerosol in the atmosphere. We investigated the detailed mechanism and kinetics of the reaction of Criegee intermediate CH$_{2}$OO with CH$_{3}$C(O)OH. The time-resolved infrared absorption spectra of transient species produced upon irradiation at 308 nm of a flowing mixture of CH$_{2}$I$_{2}$/O$_{2}$/CH$_{3}$C(O)OH at 298 K were recorded with a step-scan Fourier-transform infrared spectrometer. Bands of CH$_{2}$OO were observed initially upon irradiation; their decrease in intensity was accompanied with the appearance of bands near 886, 971, 1021, 1078, 1160, 1225, 1377, 1402, 1434, and 1777 cm$^{-1}$, assigned to the absorption of hydroperoxymethyl acetate [CH$_{3}$C(O)OCH$_{2}$OOH, HPMA], the hydrogen-transferred adduct of CH$_{2}$OO and CH$_{3}$C(O)OH. Two conformers of HPMA, an open form and an intramolecularly hydrogen-bonded form, were identified. At a later reaction period, bands of the open-form HPMA became diminished and new bands appeared at 930, 1045, 1200, 1378, 1792, and 1810 cm$^{-1}$, assigned to the formic acetic anhydride [CH$_{3}$C(O)OC(O)H, FAA], a dehydrolysis product of HPMA. The intramolecularly hydrogen-bonded HPMA is stable. From the temporal profiles of HPMA and FAA, we derived a rate coefficient k = (1.3 $\pm$ 0.3) $\times$ 10$^{-10}$ cm$^{3}$ molecule$^{-1}$ s$^{-1}$ for the reaction CH$_{2}$OO + CH$_{3}$C(O)OH to form HPMA and a rate coefficient k = 980 $\pm$ 40 s$^{-1}$ for the dehydration of the open-form HPMA to form FAA. Theoretical calculations were performed to elucidate the CH$_{2}$OO + CH$_{3}$C(O)OH reaction pathway and to understand the different reactivity of the two forms of HPMA.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Handle URL
https://hdl.handle.net/2142/116546
DOI
https://doi.org/10.15278/isms.2022.WC09
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Copyright 2022 held by the authors

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Abstracts & Presentations - 2022 International Symposium on Molecular Spectroscopy PRIMARY