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Volume 20, issue 12
Atmos. Chem. Phys., 20, 7429–7458, 2020
https://doi.org/10.5194/acp-20-7429-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.
Atmos. Chem. Phys., 20, 7429–7458, 2020
https://doi.org/10.5194/acp-20-7429-2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 26 Jun 2020

Research article | 26 Jun 2020

H migration in peroxy radicals under atmospheric conditions

Luc Vereecken1,2,3 and Barbara Nozière4 Luc Vereecken and Barbara Nozière
  • 1Department of Chemistry, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3000 Leuven, Belgium
  • 2Max Planck Institute for Chemistry, Hahn-Meitner-Weg 1, 55128 Mainz, Germany
  • 3Institute for Energy and Climate Research, IEK-8: Troposphere, Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
  • 4IRCELYON, CNRS and Université Claude Bernard Lyon, Avenue Albert Einstein 2, 69626 Villeurbanne, France

Abstract. A large data set of rate coefficients for H migration in peroxy radicals is presented and supplemented with literature data to derive a structure–activity relationship (SAR) for the title reaction class. The SAR supports aliphatic RO2 radicals; unsaturated bonds and β-oxo substitutions both endocyclic and exocyclic to the transition state ring; and α-oxo (aldehyde), –OH, –OOH, and –ONO2 substitutions, including migration of O-based hydrogen atoms. Also discussed are –C( = O)OH and –OR substitutions. The SAR allows predictions of rate coefficients k(T) for a temperature range of 200 to 450 K, with migrations spans ranging from 1,4 to 1,9-H shifts depending on the functionalities. The performance of the SAR reflects the uncertainty of the underlying data, reproducing the scarce experimental data on average to a factor of 2 and the wide range of theoretical data to a factor of 10 to 100, depending also on the quality of the data. The SAR evaluation discusses the performance in multi-functionalized species. For aliphatic RO2, we also present some experimental product identification that validates the expected mechanisms. The proposed SAR is a valuable tool for mechanism development and experimental design and guides future theoretical work, which should allow for rapid improvements of the SAR in the future. Relative multi-conformer transition state theory (rel-MC-TST) kinetic theory is introduced as an aid for systematic kinetic studies.

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Short summary
Alkyl peroxy radicals, RO2, are important intermediates in the oxidation of organic material in the atmosphere. It was shown earlier that hydrogen atom migration within RO2 can be important and results in the formation of additional oxidants and large highly oxygenated molecules that lead to more and larger aerosols. In this work we propose a method for predicting the chemical rate for these H migrations in RO2, helping atmospheric models to correctly include these reactions.
Alkyl peroxy radicals, RO2, are important intermediates in the oxidation of organic material in...
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