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Phys Chem Chem Phys

Title:		The photolysis of alpha-hydroperoxycarbonyls
Author(s):		Liu Z; Nguyen VS; Harvey J; Muller JF; Peeters J;
Address:		"State Key Laboratory of Chemical Engineering, East China University of Science and Technology, Meilong Road 130, 200237, Shanghai, China"
Journal Title:		Phys Chem Chem Phys
Year:		2018
Volume:		20
Issue:		10
Page Number:		6970 - 6979
DOI:		10.1039/c7cp08421h
ISSN/ISBN:		1463-9084 (Electronic) 1463-9076 (Linking)
Abstract:		"In this work, we theoretically elucidated the mechanism and predicted the major products of the photolysis of alpha-hydroperoxycarbonyls, known to be products of the atmospheric oxidation of biogenic volatile organic compounds (BVOC) and components of secondary organic aerosol (SOA) in rural and remote areas. Using 2-hydroperoxypropanal OCHCH(OOH)CH(3) as a model compound, we show that the likely major photolysis mechanism is a fast 1,5 H-shift in the initially excited singlet S(1) state followed by spontaneous elimination of singlet oxygen to yield an enol HOCH[double bond, length as m-dash]CHCH(3), while intersystem crossing (ISC) to the triplet T(1) state and C-C scission into HC O + HOOC HCH(3) followed by expulsion of a hydroxyl radical from the unstable HOOC HCH(3) is another product channel. The direct S(1) reaction was found to occur at such a high rate that the quantum yield in atmospheric conditions is expected to approach unity. In the atmosphere, the enol should generally react with OH radicals or tautomerize into the more stable carbonyl O[double bond, length as m-dash]CH-CH(2)CH(3). Vinylalcohol is shown to be a major end product of the photolysis of hydroperoxyacetaldehyde, an isoprene oxidation product. Taking into account also the important enhancement of the absorption cross sections over those of the constituent monofunctional compounds as observed for the analogous beta-ketohydroperoxides, (F. Jorand et al., J. Photochem. Photobiol. A: Chem., 2000, 134, 119-125) the atmospheric photolysis rate of alpha-hydroperoxycarbonyls was estimated to be in the range of (1 to 5) x 10(-4) s(-1), generally faster than the rate of their OH reactions"
Keywords:
Notes:		"PubMed-not-MEDLINELiu, Zhen Nguyen, Vinh Son Harvey, Jeremy Muller, Jean-Francois Peeters, Jozef eng England 2018/02/22 Phys Chem Chem Phys. 2018 Mar 7; 20(10):6970-6979. doi: 10.1039/c7cp08421h"