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Title:INFRARED SPECTRUM OF CHLOROMETHYL HYDROPEROXIDE CH2ClOOH PRODUCED FROM REACTION OF THE CRIEGEE INTERMEDIATE CH2OO WITH HCl
Author(s):Liang, Wei-Che
Contributor(s):Lee, Yuan-Pern
Subject(s):Vibrational structure/frequencies
Abstract:The Criegee intermediates, which are carbonyl oxides produced in ozonolysis of unsaturated hydrocarbons,\footnote{R. Criegee and G. Wenner, J. Liebigs Ann. Chem. 564, 9 (1949).} play important roles in the production of OH, aerosols and organic acids in the atmosphere. Criegee intermediates react readily with other atmospheric species such as \chem{NO_2}, \chem{SO_2}, (\chem{H_2O})$_{2}$ and HCl. The reaction of \chem{CH_2OO} with HCl was reported to be rapid, with a rate coefficient of 4.6$\times$10$^{-11}$ cm$^{3}$ molecule$^{-1}$ s$^{-1}$.\footnote{Elizabeth S. Foreman, Kara M. Kapnas, Craig Murray, Angew. Chem. Int. Ed. 55, 1 (2016).} Quantum-chemical calculations indicate that the reaction \chem{CH_2OO} + HCl proceeds through a barrierless association reaction to form chloromethyl hydroperoxide (CMHP, \chem{CH_2ClOOH}), which was predicted to have three stable conformations, denoted as gauche-gauche CMHP, anti-CMHP and gauche-anti CMHP; the first two conformers were observed by microwave spectroscopy.\footnote{C. Cabezas and Y. Endo, ChemPhysChem. 18, 1860 (2017).} In this work, a step-scan Fourier-transform spectrometer coupled with a multipass absorption cell was employed to record temporally resolved infrared (IR) absorption spectra of the reactants and products during the reaction of \chem{CH_2OO} with HCl in a flow system. \chem{CH_2OO} was produced from the reaction of \chem{O_2} with \chem{CH_2I}, which was produced via photolysis of \chem{CH_2I_2} at 308 nm.\footnote{Y.-Y. Wang, C.-Y. Chung, and Y.-P. Lee, J. Chem. Phys. 145, 154303 (2016).} Time-resolved IR absorption spectra were recorded at resolution 0.25 \wn. The spectrum of gauche-gauche CMHP was characterized by the absorption bands at 1061.4, 1309.4, 1359.9 \wn, and the spectrum of gauche-anti CMHP was characterized by the absorption bands at 1054.8, 1310.3, 1359.3 \wn. The observed wavenumbers, rotational contours and relative intensities agree with those predicted with the B3LYP/aug-cc-PVTZ method; contributions of the hot bands from excited states of the low-lying torsional modes are significant.
Issue Date:06/22/18
Publisher:International Symposium on Molecular Spectroscopy
Citation Info:APS
Genre:Conference Paper / Presentation
Type:Text
Language:English
URI:http://hdl.handle.net/2142/100664
DOI:10.15278/isms.2018.FA02
Other Identifier(s):FA02
Date Available in IDEALS:2018-08-17
2018-12-12


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