Theoretical Investigation of the OH<sup>.</sup>‐Initiated Oxidation of Benzaldehyde in the Troposphere

Iuga, Cristina; Galano, Annia; Vivier–Bunge, Annik

doi:10.1002/cphc.200800144

Cited by 19 publications

(4 citation statements)

References 56 publications

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“…Therefore (and according to Hammond’s postulate) there must be a direct relation between the L value and the heat of reaction of a specific pathway. Since deviations from this postulate have previously been reported for other systems, we decided to verify if the reactions studied in the present work are in line with the rule or with the exceptions. Figure A shows that, in general, HAT mechanisms involving carotenoids and the OOH free radical obey Hammond’s postulate, i.e., the earlier the transition state the more exothermic the reaction.…”

Section: Resultsmentioning

confidence: 58%

Reactions of OOH Radical with β-Carotene, Lycopene, and Torulene: Hydrogen Atom Transfer and Adduct Formation Mechanisms

Galano

Francisco‐Márquez

2009

J. Phys. Chem. B

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The relative free radical scavenging activity of beta-carotene, lycopene, and torulene toward OOH radicals has been studied using density functional theory. Hydrogen atom transfer (HAT) and radical adduct formation (RAF) mechanisms have been considered. All the possible reaction sites have been included in the modeling, and detailed branching ratios are reported for the first time. The reactions of hydrocarbon carotenoids (Car) with peroxyl radicals, in both polar and nonpolar environments, are predicted to proceed via RAF mechanism, with contributions higher than 98% to the overall OOH + Car reactions. Lycopene and torulene were found to be more reactive than beta-carotene. In nonpolar environments the reactivity of the studied carotenoids toward peroxyl radical follows the trend LYC > TOR > BC, whereas in aqueous solutions it is TOR > LYC > BC. OOH adducts are predicted to be formed mainly at the terminal sites of the conjugated polyene chains. The main addition sites were found to be C5 for beta-carotene and lycopene and C30 for torulene. The general agreement between the calculated magnitudes and the available experimental data supports the predictions from this work.

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Section: Resultsmentioning

confidence: 58%

Reactions of OOH Radical with β-Carotene, Lycopene, and Torulene: Hydrogen Atom Transfer and Adduct Formation Mechanisms

Galano

Francisco‐Márquez

2009

J. Phys. Chem. B

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“…Thus, the earliness of the TSs can be directly inferred from the forming C· · ·F distance. That is, the longer the C· · ·F distance is, the earlier the TS is (Iuga et al, 2008). Figure S2 showed that the F-TS add-Cl pathway was the earliest among three addition TSs, suggesting that this pathway was more exothermic than the F-R add-F and F-R add-Br pathways according to the Hammond postulate (Hammond, 1955).…”

Section: X-addition Pathwaysmentioning

confidence: 98%

A theoretical model on the formation mechanism and kinetics of highly toxic air pollutants from halogenated formaldehydes reacted with halogen atoms

Wang

Gao

et al. 2013

Atmos. Chem. Phys.

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Abstract. The atmospheric reactions of halogenated formaldehydes with halogen atoms were investigated by high-accuracy molecular orbital calculation. Our studies showed that compared to X-addition pathway, the H-abstraction pathway was demonstrated to be more preferred to form halogenated formyl radicals and hydrogen halides (HX). In specific areas with abundant halogen atoms, such as the marine boundary layer (MBL), halogenated formyl radical was reacted easily with halogen atoms and finally transformed into HX and CO2 in the presence of water; otherwise, this radical was degraded to CO2, halogen gas, and halogenated oxide in the presence of O2 and halogen atoms. By using the canonical variational transition state theory, the kinetics calculations were performed within a wide atmospheric temperature range of 200–368 K, and theoretical values agreed well with the available experimental data. Under atmospheric conditions, rate constants decreased as altitude increased, and especially the rate constants of halogen atoms reacted with FCHO quickly reduced. The kinetic results showed that although the reactions of halogenated formaldehydes with F atoms occurred more easily than did those with Cl and Br atoms, the two latter reactions were still important atmospheric degradation process, especially in the MBL. The modified Arrhenius equations of rate constants within the atmospheric temperature range were fitted, which helped to understand the established atmospheric model and estimated the contribution of title reactions to atmospheric chemistry pollution.

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“…Table 3 and Figure 2(b) show that channel (8) is exothermic by 11.02 kcal mol -1 and channel (9) is endothermic by 18.53 kcal mol -1 , inconsistent with Hammond's postulate. Deviations from Hammond's postulate have previously been observed for other systems [40,41]. Due to the existence of the hydrogen bond in TS7, channel (7) has a lower barrier height, with 41.18 kcal mol -1 than channels (8) and (9) with 41.78 and 43.98 kcal mol -1 , respectively.…”

Section: Attack On the Carbon Atom Perpendicular To C -C Bond Axismentioning

confidence: 76%

Theoretical study of a reaction mechanism of tropospheric interest: CH₃CH₂F + OH

Wang

et al. 2013

Progress in Reaction Kinetics and Mechanism

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Dual-level electronic structure calculation has been performed to investigate the mechanism and all possible channels of OH radical reaction with CH 3 CH 2 F. Geometries and frequencies are computed at the B3LYP/6-311G(d,p) level of theory for all stationary points and complexes and transition states are located. Potential energy surfaces are constructed at the PMP2/cc-pVTZ//B3LYP/6-311G(d,p) level + ZPE correction. Four types of reaction channels are identified: hydrogen abstraction, fluorine abstraction and attack on carbon atom along or perpendicular to the C -C bond axis. Hydrogen abstraction channels have lower barriers and are more exothermic, while out-of-plane β -H abstraction with the lowest barrier is competitive with α -H abstraction. Due to the high energy barrier, contributions of non-H abstraction channels are excluded. The influence of hydrogen bonding interaction is clearly observed in the barrier heights.

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Theoretical Investigation of the OH^.‐Initiated Oxidation of Benzaldehyde in the Troposphere

Cited by 19 publications

References 56 publications

Reactions of OOH Radical with β-Carotene, Lycopene, and Torulene: Hydrogen Atom Transfer and Adduct Formation Mechanisms

Reactions of OOH Radical with β-Carotene, Lycopene, and Torulene: Hydrogen Atom Transfer and Adduct Formation Mechanisms

A theoretical model on the formation mechanism and kinetics of highly toxic air pollutants from halogenated formaldehydes reacted with halogen atoms

Theoretical study of a reaction mechanism of tropospheric interest: CH₃CH₂F + OH

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Theoretical Investigation of the OH.‐Initiated Oxidation of Benzaldehyde in the Troposphere

Cited by 19 publications

References 56 publications

Reactions of OOH Radical with β-Carotene, Lycopene, and Torulene: Hydrogen Atom Transfer and Adduct Formation Mechanisms

Reactions of OOH Radical with β-Carotene, Lycopene, and Torulene: Hydrogen Atom Transfer and Adduct Formation Mechanisms

A theoretical model on the formation mechanism and kinetics of highly toxic air pollutants from halogenated formaldehydes reacted with halogen atoms

Theoretical study of a reaction mechanism of tropospheric interest: CH3CH2F + OH

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Theoretical Investigation of the OH^.‐Initiated Oxidation of Benzaldehyde in the Troposphere

Theoretical study of a reaction mechanism of tropospheric interest: CH₃CH₂F + OH