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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/18895

Title: Theoretical Study of the Oxidation Mechanisms of Naphthalene Initiated by Hydroxyl Radicals: the O2 Addition Reaction Pathways
Authors: Shiroudi, Abolfazl
Deleuze, Michael S.
Canneaux, Sébastien
Issue Date: 2015
Citation: PHYSICAL CHEMISTRY CHEMICAL PHYSICS, 17 (20), p. 13719-13732
Abstract: Atmospheric oxidation of the naphthalene–OH adduct [C10H8OH](R1) by molecular oxygen in its triplet electronic ground state has been studied using density functional theory along with the B3LYP, oB97XD, UM05-2x and UM06-2x exchange–correlation functionals. From a thermodynamic viewpoint, the most favorable process is O2 addition at the C2 position in syn mode, followed by O2 addition at the C2 position in anti mode, O2 addition at the C4 position in syn mode, and O2 addition at the C4 position in anti mode, as the second, third and fourth most favorable processes. The syn modes of addition at these positions are thermodynamically favored over the anti ones by the formation of an intramolecular hydrogen bond between the hydroxyl and peroxy substituents. Analysis of the computed structures, bond orders and free energy profiles demonstrate that the reaction steps involved in the oxidation of the naphthalene–OH adduct by O2 satisfy Hammond’s principle. Kinetic rate constants and branching ratios under atmospheric pressure and in the fall-off regime have been supplied, using transition state and RRKM theories. By comparison with experiment, these data confirm the relevance of a two-step reaction mechanism. Whatever the addition mode, O2 addition in C4 position is kinetically favored over O2 addition in C2 position, in contrast with the expectations drawn from thermodynamics and reaction energies. Under a kinetic control of the reaction, and in line with the computed reaction energy barriers, the most efficient process is O2 addition at the C4 position in syn mode, followed by O2 addition at the C2 position in syn mode, O2 addition at the C4 position in anti mode, and O2 addition at the C2 position in anti mode as the second, third and fourth most rapid processes. The computed branching ratios also indicate that the regioselectivity of the reaction decreases with increasing temperatures and decreasing pressures.
Notes: [Shiroudi, A.; Deleuze, M. S.] Hasselt Univ, Ctr Mol & Mat Modelling, B-3590 Diepenbeek, Belgium. [Canneaux, S.] Univ Lille 1, Sci & Technol, F-59655 Villeneuve Dascq, France.
URI: http://hdl.handle.net/1942/18895
DOI: 10.1039/C5CP01934F
ISI #: 000354416700060
ISSN: 1463-9076
Category: A1
Type: Journal Contribution
Validation: ecoom, 2016
Appears in Collections: Research publications

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