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Phys Chem Chem Phys

Title:		Unimolecular reaction chemistry of a charge-tagged beta-hydroxyperoxyl radical
Author(s):		So S; Kirk BB; Trevitt AJ; Wille U; Blanksby SJ; da Silva G;
Address:		"Department of Chemical and Biomolecular Engineering, The University of Melbourne, VIC 3010, Australia. gdasilva@unimelb.edu.au"
Journal Title:		Phys Chem Chem Phys
Year:		2014
Volume:		16
Issue:		45
Page Number:		24954 - 24964
DOI:		10.1039/c4cp02981j
ISSN/ISBN:		1463-9084 (Electronic) 1463-9076 (Linking)
Abstract:		"beta-Hydroxyperoxyl radicals are formed during atmospheric oxidation of unsaturated volatile organic compounds such as isoprene. They are intermediates in the combustion of alcohols. In these environments the unimolecular isomerization and decomposition of beta-hydroxyperoxyl radicals may be of importance, either through chemical or thermal activation. We have used ion-trap mass spectrometry to generate the distonic charge-tagged beta-hydroxyalkyl radical anion, CH2C(OH)(CH3)CH2C(O)O(-), and investigated its subsequent reaction with O2 in the gas phase under conditions that are devoid of complicating radical-radical reactions. Quantum chemical calculations and master equation/RRKM theory modeling are used to rationalize the results and discern a reaction mechanism. Reaction is found to proceed via initial hydrogen abstraction from the gamma-methylene group and from the beta-hydroxyl group, with both reaction channels eventually forming isobaric product ions due to loss of either OH + HCHO or OH + CO2. Isotope labeling studies confirm that a 1,5-hydrogen shift from the beta-hydroxyl functionality results in a hydroperoxyalkoxyl radical intermediate that can undergo further unimolecular dissociations. Furthermore, this study confirms that the facile decomposition of beta-hydroxyperoxyl radicals can yield OH in the gas phase"
Keywords:		"*Electrons Hydroxyl Radical/*chemistry Mass Spectrometry Models, Molecular Molecular Conformation Oxygen/chemistry Peroxides/*chemistry Quantum Theory;"
Notes:		"MedlineSo, Sui Kirk, Benjamin B Trevitt, Adam J Wille, Uta Blanksby, Stephen J da Silva, Gabriel eng Research Support, Non-U.S. Gov't England 2014/10/18 Phys Chem Chem Phys. 2014 Dec 7; 16(45):24954-64. doi: 10.1039/c4cp02981j"