Correlation-type structure activity relationships for the kinetics of the decomposition of simple and β-substituted alkoxyl radicals

Johnson, David C.; Cassanelli, Paola; Cox, R. A.

doi:10.1016/j.atmosenv.2003.12.027

Cited by 18 publications

(26 citation statements)

References 30 publications

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“…Curran's estimations 55 deviate from the present and Somnitz's results at both high and low temperatures. The estimated rate data based on the experimental data of Baldwin et al 26,27 are substantially below these theoretical data whereas Johnson et al's estimation, 28 which is supposed to be valid at 1 atm, overshoots the theoretical high-pressure data at low temperatures.…”

Section: 2 High-level Energy Calculation High-level Energy Calculamentioning

confidence: 90%

Ab Initio Kinetics for the Decomposition of Hydroxybutyl and Butoxy Radicals ofn-Butanol

2013

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The decomposition kinetics of the hydroxybutyl and butoxy radicals (C4H9O) arising via H abstraction from n-butanol were studied theoretically with ab initio transition-state-theory-based master equation analyses. Stationary points on the C4H9O potential energy surface were calculated at either the RQCISD(T)/CBS//B3LYP/6-311++G(d,p) level or the RQCISD(T)/CBS//CASPT2/aug-cc-pVDZ level. Unimolecular pressure- and temperature-dependent rate coefficients were calculated over broad ranges of temperature (300-2500 K) and pressure (1.3 × 10(-3) to 10(2) atm) by solving the time-dependent multiple-well master equation. The "well merging" phenomenon was observed and analyzed for its influence on the branching ratios and rate coefficients. The theoretical predictions were compared with the available experimental and theoretical data and any discrepancies were analyzed. The predicted rate coefficients are represented with forms that may readily be used in combustion modeling of n-butanol.

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Section: 2 High-level Energy Calculation High-level Energy Calculamentioning

confidence: 90%

Ab Initio Kinetics for the Decomposition of Hydroxybutyl and Butoxy Radicals ofn-Butanol

2013

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“…This suggests that either R 3 O · radicals are formed in these reactions, which might be true also for reaction (19), or that reaction (4c) takes place in these systems to produce another mixture of R · radicals than reaction (15). R 3 O · radicals might decompose via: [47] CHRЈRЈЈO · Ǟ fast · CRЈRЈЈOH (26) This is, for example, expected to happen for fatty acid hydroperoxides, which are formed biologically, or for the radical formed from (CH 3 ) 3 COOH via: (27) with k = 2.0 × 10 3 s -1 , [48] etc.…”

Section: ·-mentioning

confidence: 98%

The Fenton Reaction in Aerated Aqueous Solutions Revisited

et al. 2005

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The oxidation of alcohols in aerated acidic aqueous solutions by the Fenton reagent is a chain reaction. The length of the chain depends linearly on the number of CHnOR (n = 1 or 2) groups in the alcohol. The reaction is accelerated by increasing the concentration of Fe(H2O)62+, but this cation is also active in at least one of the termination steps of the chain reaction. Addition of ethanol to a solution containing sucrose shortens the chain length. Saturation with dioxygen, instead of air, increases the chain length. An increase in alcohol concentration increases the chain length up to a limiting value. A complicated mechanism, which is in agreement with all these observations, is proposed. However, efforts to simulate the mechanism succeed only in simulating the Fe(H2O)63+ yield, but indicate that the observed process is considerably faster than the predicted one. In the latter the rate‐determining step is the Fenton reaction, the rate constant of which is well known. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…Although the discrepancies cannot be fully reconciled, the present simulations lead to an improved agreement in the model-measurement comparison for all seven species for the 6 August case study, by virtue of increases in the simulated concentrations of acetaldehyde, butanal, pentanal, hexanal and acetone, and decreases for butanone and 3-methylbutanone. Although there are almost certainly a number of contributing factors, the general influence of temperature on the competition between alkoxy radical decomposition reactions and their reactions with O 2 plays a notable role, the former reactions being strongly temperaturedependent (e.g., Johnson et al, 2004b). As discussed previously (Utembe et al, 2005), the oxidation of the most abundant emitted anthropogenic VOC, butane, provides a good example, because it is a major source of butanone and also generates acetaldehyde.…”

Section: Simulations Of Gas-phase Speciesmentioning

confidence: 99%

Simulating regional scale secondary organic aerosol formation during the TORCH 2003 campaign in the southern UK

et al. 2006

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Abstract.A photochemical trajectory model has been used to simulate the chemical evolution of air masses arriving at the TORCH field campaign site in the southern UK during late July and August 2003, a period which included a widespread and prolonged photochemical pollution episode. The model incorporates speciated emissions of 124 nonmethane anthropogenic VOC and three representative biogenic VOC, coupled with a comprehensive description of the chemistry of their degradation. A representation of the gas/aerosol absorptive partitioning of ca. 2000 oxygenated organic species generated in the Master Chemical Mechanism (MCM v3.1) has been implemented, allowing simulation of the contribution to organic aerosol (OA) made by semi-and non-volatile products of VOC oxidation; emissions of primary organic aerosol (POA) and elemental carbon (EC) are also represented. Simulations of total OA mass concentrations in nine case study events (optimised by comparison with observed hourly-mean mass loadings derived from aerosol mass spectrometry measurements) imply that the OA can be ascribed to three general sources: (i) POA emissions; (ii) a "ubiquitous" background concentration of 0.7 µg m −3 ; and (iii) gas-to-aerosol transfer of lower volatility products of VOC oxidation generated by the regional scale processing of emitted VOC, but with all partitioning coefficients increased by a species-independent factor of 500. The requirement to scale the partitioning coefficients, and the implied background concentration, are both indicative of the occurrence of chemical processes within the aerosol which allow the oxidised organic species to react by association and/or accretion reactions which generate even lower volatility products, leading to a persistent, non-volatile secondary organic aerosol (SOA). The contribution of secondary organic mateCorrespondence to: M. E. Jenkin (m.jenkin@imperial.ac.uk) rial to the simulated OA results in significant elevations in the simulated ratio of organic carbon (OC) to EC, compared with the ratio of 1.1 assigned to the emitted components. For the selected case study events, [OC]/[EC] is calculated to lie in the range 2.7-9.8, values which are comparable with the high end of the range reported in the literature.

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Correlation-type structure activity relationships for the kinetics of the decomposition of simple and β-substituted alkoxyl radicals

Cited by 18 publications

References 30 publications

Ab Initio Kinetics for the Decomposition of Hydroxybutyl and Butoxy Radicals ofn-Butanol

Ab Initio Kinetics for the Decomposition of Hydroxybutyl and Butoxy Radicals ofn-Butanol

The Fenton Reaction in Aerated Aqueous Solutions Revisited

Simulating regional scale secondary organic aerosol formation during the TORCH 2003 campaign in the southern UK

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