Ultraviolet absorption spectra and kinetics of acetonyl and acetonylperoxy radicals

Abstract. This article, the second in the series, presents kinetic and photochemical data evaluated by the IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry. It covers the gas phase and photochemical reactions of Organic species, which were last published in 1999, and were updated on the IUPAC website in late 2002, and subsequently during the preparation of this article. The article consists of a summary table of the recommended rate coefficients, containing the recommended kinetic parameters for the evaluated reactions, and eight appendices containing the data sheets, which provide information upon which the recommendations are made.

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“…The preferred values are based on the study of Cox et al (1990). Because this is the only study of this reaction, we assign large error limits.…”

Section: Comments On Preferred Valuesmentioning

confidence: 99%

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

et al. 2006

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“…Quantum-chemical calculations (see above) shows that Reaction (R8) cannot be a unimolecular reaction such as H-atom migration, because they are not fast enough to compete with other RO 2 reaction channels. Photolysis of RO 2 that could results in OH/HO 2 have been observed for acetylperoxy radicals (Cox et al, 1990) and isoprene derived RO 2 (Hansen et al, 2017). However, the reaction rate constant of 0.006 ± 0.004 s −1 needed here to explain observations would require an unrealistically high absorption cross section.…”

Section: Potential Additional Ro 2 Reaction Channelmentioning

confidence: 88%

Investigation of the oxidation of methyl vinyl ketone (MVK) by OH radicals in the atmospheric simulation chamber SAPHIR

Fuchs¹,

Albrecht²,

Acir

et al. 2018

Atmos. Chem. Phys.

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Abstract. The photooxidation of methyl vinyl ketone (MVK) was investigated in the atmospheric simulation chamber SAPHIR for conditions at which organic peroxy radicals (RO 2 ) mainly reacted with NO ("high NO" case) and for conditions at which other reaction channels could compete ("low NO" case). Measurements of trace gas concentrations were compared to calculated concentration time series applying the Master Chemical Mechanism (MCM version 3.3.1). Product yields of methylglyoxal and glycolaldehyde were determined from measurements. For the high NO case, the methylglyoxal yield was (19 ± 3) % and the glycolaldehyde yield was (65 ± 14) %, consistent with recent literature studies. For the low NO case, the methylglyoxal yield reduced to (5 ± 2) % because other RO 2 reaction channels that do not form methylglyoxal became important. Consistent with literature data, the glycolaldehyde yield of (37 ± 9) % determined in the experiment was not reduced as much as implemented in the MCM, suggesting additional reaction channels producing glycolaldehyde. At the same time, direct quantification of OH radicals in the experiments shows the need for an enhanced OH radical production at low NO conditions similar to previous studies investigating the oxidation of the parent VOC isoprene and methacrolein, the second major oxidation product of isoprene. For MVK the model-measurement discrepancy was up to a factor of 2. Product yields and OH observations were consistent with assumptions of additional RO 2 plus HO 2 reaction channels as proposed in literature for the major RO 2 species formed from the reaction of MVK with OH. However, this study shows that also HO 2 radical concentrations are underestimated by the model, suggesting that additional OH is not directly produced from RO 2 radical reactions, but indirectly via increased HO 2 . Quantum chemical calculations show that HO 2 could be produced from a fast 1,4-H shift of the second most important MVK derived RO 2 species (reaction rate constant 0.003 s −1 ). However, additional HO 2 from this reaction was not sufficiently large to bring modelled HO 2 radical concentrations into agreement with measurements due to the small yield of this RO 2 species. An additional reaction channel of the major RO 2 species with a reaction rate constant of (0.006 ± 0.004) s −1 would be required that produces concurrently HO 2 radicals and glycolaldehyde to achieve modelmeasurement agreement. A unimolecular reaction similar to the 1,5-H shift reaction that was proposed in literature for RO 2 radicals from MVK would not explain product yields for conditions of experiments in this study. A set of H-migration reactions for the main RO 2 radicals were investigated by quantum chemical and theoretical kinetic methodologies, but did not reveal a contributing route to HO 2 radicals or glycolaldehyde.

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“…However, by analogy to the corresponding reactions where R = CH3 [12,13] and R = CH3COCH2 [9], K12 was estimated to be approximately 5.0 x lo-" cm3 molecule-' s-'.…”

Section: Absorption Spectra Of Cfc12ch202 and Cf2clch202mentioning

confidence: 99%

“…The yield of F atoms was established by monitoring the transient absorption at 216.4 nm of methyl radicals produced by radiolysis of SF6/CH4 mixtures as described in detail elsewhere [8,9]. In the present series of experiments, using a value of 4.12 x cm2 molecule-' for a(CH3) at 216.4 nm [lo, 111, the yield of F atoms at 1000 mbar of SF6 was measured to be 2.8 X 1015 cm-3 at full irradiation dose.…”

Section: Absorption Spectra Of Cfc12ch202 and Cf2clch202mentioning

confidence: 99%

UV absorption spectra and kinetics of the self reaction of CFCl₂CH₂O₂ and CF₂ClCH₂O₂ radicals in the gas phase at 298 K

Wallington

Nielsen

1991

Int J of Chemical Kinetics

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The ultraviolet absorption spectra of the peroxy radicals derived from hydrochlorofluorocarbons 141b and 142b, (CFClzCHZOz and CFzClCHz02, respectively), and the kinetics of their self reactions have been studied in the gas phase at 298 K using a pulse radiolysis technique. Absorption cross sections were quantified over the wavelength range 220-300 nm. Measured absorption cross sections at 250 nm were indistinguishable within the experimental uncertainties (~10%) and yield;Errors represent the sum of statistical uncertainty and our estimate of potential systematic errors. Our absorption cross section data were then used to derive the observed self reaction rate constants for reactions (1) and (2), defined asCFzCICHzOz + CFzClCHzOz --j products of klobs = (4.36 5 0.64) x lo-'' and k2,,bs = (4.13 -+ 0.58) x lo-'' cm3 molecule-' s-', quoted errors represent 2a. These results are discussed with respect to previous studies of the absorption spectra and kinetics of peroxy radicals

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Ultraviolet absorption spectra and kinetics of acetonyl and acetonylperoxy radicals

Cited by 45 publications

References 14 publications

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

Investigation of the oxidation of methyl vinyl ketone (MVK) by OH radicals in the atmospheric simulation chamber SAPHIR

UV absorption spectra and kinetics of the self reaction of CFCl₂CH₂O₂ and CF₂ClCH₂O₂ radicals in the gas phase at 298 K

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Ultraviolet absorption spectra and kinetics of acetonyl and acetonylperoxy radicals

Cited by 45 publications

References 14 publications

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

Evaluated kinetic and photochemical data for atmospheric chemistry: Volume II – gas phase reactions of organic species

Investigation of the oxidation of methyl vinyl ketone (MVK) by OH radicals in the atmospheric simulation chamber SAPHIR

UV absorption spectra and kinetics of the self reaction of CFCl2CH2O2 and CF2ClCH2O2 radicals in the gas phase at 298 K

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UV absorption spectra and kinetics of the self reaction of CFCl₂CH₂O₂ and CF₂ClCH₂O₂ radicals in the gas phase at 298 K