A kinetic and mechanistic study of the gas-phase reactions of OH radicals and Cl atoms with some halogenated acetones and their atmospheric implications

Carr, Sinéad; Shallcross, Dudley E.; Canosa‐Mas, Carlos E.; Wenger, John C.; Sidebottom, Howard; Treacy, Jack; Wayne, Richard P.

doi:10.1039/b304298g

Cited by 42 publications

(42 citation statements)

References 53 publications

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“…5 if not enough unsaturated/aromatic double bonds for addition are available (see below). On the other hand, the FTIR and UV/VIS spectra indicate the sufficient presence of such sites for addition, and such radical-radical reactions are suppressed due to the high concentration of O 2 that quickly leads to the formation of RO 2 radicals (Reaction R1c) (Wallington et al, 1989;Carr et al, 2003).…”

Section: Related Mechanisms Of Halogen Chemistrymentioning

confidence: 99%

“…4 (2975-2950 cm −1 : hydrogen abstraction from -CH 3 ; 2940-2915 cm −1 : hydrogen abstraction from -CH 2 -; 2890-2880 cm −1 : hydrogen abstraction from -CH(-)- (Socrates, 1980), corresponding to the weaker bond energies of secondary and tertiary C-H bonds). Hydrogen abstraction from methyl groups located close to oxygen or halogen containing functional groups was discussed in detail by Carr et al (2003). Halogen addition to unsaturated bonds is the preferred pathway for bromine atoms (Reaction R2) since their abstraction reactions are much slower than those of chlorine atoms.…”

Section: Related Mechanisms Of Halogen Chemistrymentioning

confidence: 99%

“…The transformation pathways of this model substance are summarized by Yu et al (2008). The formation of secondary organic aerosol from catechol and guaiacol by ozone was investigated by Coeur-Tourneur et al (2009), Ofner et al (2010 and (2011). The use of these aerosols as a model for the aromatic fraction of atmospheric HULIS has been discussed based on physicochemical studies.…”

Section: Introductionmentioning

confidence: 99%

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Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

et al. 2012

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Abstract. Reactive halogen species (RHS), such as X·, X 2 and HOX containing X = chlorine and/or bromine, are released by various sources like photo-activated sea-salt aerosol or from salt pans, and salt lakes. Despite many studies of RHS reactions, the potential of RHS reacting with secondary organic aerosol (SOA) and organic aerosol derived from biomass-burning (BBOA) has been neglected. Such reactions can constitute sources of gaseous organohalogen compounds or halogenated organic matter in the tropospheric boundary layer and can influence physicochemical properties of atmospheric aerosols.Model SOA from α-pinene, catechol, and guaiacol was used to study heterogeneous interactions with RHS. Particles were exposed to molecular chlorine and bromine in an aerosol smog-chamber in the presence of UV/VIS irradiation and to RHS, released from simulated natural halogen sources like salt pans. Subsequently, the aerosol was characterized in detail using a variety of physicochemical and spectroscopic methods. Fundamental features were correlated with heterogeneous halogenation, which results in new functional groups (FTIR spectroscopy), changes UV/VIS absorption, chemical composition (ultrahigh resolution mass spectroscopy (ICR-FT/MS)), or aerosol size distribution. However, the halogen release mechanisms were also found to be affected by the presence of organic aerosol. Those interaction processes, changing chemical and physical properties of the aerosol are likely to influence e.g. the ability of the aerosol to act as cloud condensation nuclei, its potential to adsorb other gases with low-volatility, or its contribution to radiative forcing and ultimately the Earth's radiation balance.

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Section: Related Mechanisms Of Halogen Chemistrymentioning

confidence: 99%

Section: Related Mechanisms Of Halogen Chemistrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

et al. 2012

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“…At the (U)CAM-B3LYP/6-311++G(2d,2p) level, the difference in the C-H bond dissociation enthalpy in the -CH 2 Cl group from that of the -CH 3 group was calculated to be −6.3 and −7.2 kcal mol −1 for the gauche-and syn-conformers, respectively. The Cl substitution lowered the bond strength of the C-H bond of the -CH 2 Cl group [9]. The rate constants for the H-atom abstraction from the -CH 2 Cl group were calculated to be one order of magnitude larger than those from the -CH 3 group.…”

Section: Resultsmentioning

confidence: 99%

“…The abstraction product acetonyl radical is also an important intermediate species that yields peroxy radicals through the reaction with O 2 [7,8]. From the environmental point of view strongly linked with the depletion of the ozone layer, Carr et al investigated the gas-phase reaction of the OH radical with halogenated acetones and determined the rate constants at 298 K [9]. However, since the product analysis has not been carried out yet, the detailed mechanism of chloroacetone oxidation remains uncertain.…”

Section: Introductionmentioning

confidence: 99%

Computational study of the reaction between chloroacetone and OH radical

Tanaka

Yamagishi

Nishikiori

2013

Computational and Theoretical Chemistry

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In this study, the reaction of the chloroacetone with OH radical was studied theoretically using density functional theory (DFT) and transition state theory. The potential energy surface of the reaction was calculated at the CAM-B3LYP/6-311++G(2d,2p) and M06-2X/6-311++G(2d,2p) levels. We initially considered four possible reaction paths: (1) the hydrogen atom abstraction from chloroacetone by OH radical; (2) the addition of the OH radical to the carbonyl carbon; (3) chlorine atom abstraction; and (4) S N 2 displacement. The conventional transition state theory was employed to calculate the rate constants. The hydrogen abstraction from the -CH 2 Cl group was found to be dominant. Since, the predicted total rate constant at the CAM-B3LYP/6-311++G(2d,2p) level was in good agreement with the experimental value at 298 K, the level of theory used in this study to describe this reaction is appropriate.

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Theoretical Dynamic Studies on the Reaction of CH₃C(O)CH_3−nF_n with the Hydroxyl Radical and the Chlorine Atom

Wang

et al. 2006

ChemPhysChem

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The mechanisms of the reactions: CH(3)C(O)CH(2)F+OH/Cl-->products (R1/R2) and CH(3)C(O)CF(3)+OH/Cl-->products (R3/R4) are studied over a wide temperature range (200-2000 K) by means of the dual-level direct dynamics method. The optimized geometries and frequencies of the stationary points are calculated at the MP2/cc-pVDZ and B3LYP/6-311G(d,p) levels. The energy profiles of the reactions are then refined with the interpolated single-point-energy method (ISPE) at the BMC-CCSD level. The canonical variational transition-state theory (CVT) with the small-curvature-tunneling (SCT) correction method is used to calculate the rate constants. Using group-balanced isodesmic reactions as working chemical reactions, the standard enthalpies of formation for CH(3)C(O)CH(2)F, CH(3)C(O)CF(3), CH(3)C(O)CHF, CH(2)C(O)CH(2)F, and CH(2)C(O)CF(3) are evaluated at the CCSD(T)/6-311+G(2d,p)//MP2/cc-pVDZ level of theory. The results indicate that the hydrogen abstraction is dominated by removal from the fluoromethyl position rather than from the methyl position.

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A kinetic and mechanistic study of the gas-phase reactions of OH radicals and Cl atoms with some halogenated acetones and their atmospheric implications

Cited by 42 publications

References 53 publications

Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

Computational study of the reaction between chloroacetone and OH radical

Theoretical Dynamic Studies on the Reaction of CH₃C(O)CH_3−nF_n with the Hydroxyl Radical and the Chlorine Atom

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A kinetic and mechanistic study of the gas-phase reactions of OH radicals and Cl atoms with some halogenated acetones and their atmospheric implications

Cited by 42 publications

References 53 publications

Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

Halogenation processes of secondary organic aerosol and implications on halogen release mechanisms

Computational study of the reaction between chloroacetone and OH radical

Theoretical Dynamic Studies on the Reaction of CH3C(O)CH3−nFn with the Hydroxyl Radical and the Chlorine Atom

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Theoretical Dynamic Studies on the Reaction of CH₃C(O)CH_3−nF_n with the Hydroxyl Radical and the Chlorine Atom