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Reactivity of syn-CH3CHOO with H2O enhanced through a roaming mechanism in the entrance channel

Nature Chemistry volume 17, pages 897–903 (2025)Cite this article

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Abstract

Criegee intermediates are highly reactive species that play a pivotal role in the chemistry of the atmosphere, substantially impacting global climate and air quality. They are formed through the reaction of ozone with alkenes and considerably influence the formation of hydroxyl radicals and aerosols through their unimolecular decomposition and their reaction with key atmospheric components, respectively. However, their interaction with water vapour, a major atmospheric component, remains inadequately characterized. Here, using both time-dependent laser-induced fluorescence experiments and full-dimensional dynamics calculations, we investigate the reaction of syn-CH3CHOO, a prevalent Criegee intermediate, with water vapour. Our results reveal a much higher reaction rate than previously estimated, challenging the conventional notion that unimolecular decomposition dominates syn-CH3CHOO removal. Notably, we uncover a complex mechanism involving a roaming process that enhances reactivity. Our findings necessitate a revised assessment of reactions involving syn-mono- and di-substituted Criegee intermediates with water, which are crucial for accurately estimating the OH budget derived from these intermediates.

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Fig. 1: Experimental observed consumption of syn-CH3CHOO by water, and comparison with previously calculated results.
Fig. 2: Potential energy surface of the syn-CH3CHOO + H2O reaction.
Fig. 3: Rate coefficients for the syn-CH3CHOO + H2O reaction.
Fig. 4: Snapshots of a typical trajectory illustrating the roaming reaction mechanism.

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Data supporting the findings of this study can be accessed at figshare at https://doi.org/10.6084/m9.figshare.28630718.v1 (ref. 61). Source data are provided with this paper.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (grant nos. 22288201 (D.H.Z.), 22173099 (B.F.), 21873098 (W.D.) and 22203092 (Y.F.)); the Scientific Instrument Developing Project of the Chinese Academy of Sciences (grant no. GJJSTD20220001 to X.Y.); the Strategic Priority Research Program of the Chinese Academy of Sciences (grant no. XDB0970203 to B.F.), the Innovation Program for Quantum Science and Technology (grant no. 2021ZD0303305 to D.H.Z.), Guangdong Science and Technology Program (grant nos. 2019ZT08L455 and 2019JC01X091 to X.Y.) and the Shenzhen Science and Technology Program (grant no. ZDSYS20200421111001787 to X.Y.). We thank the staff members of the Free Radical Detection Station (31127.02.DCLS.FRDS) at the Dalian Coherent Light Source (31127.02.DCLS) for providing technical support during the experiment. We acknowledge Y. V. Suleymanov, D. Manolopoulos and W. Fang for insightful discussions about the possible ring-polymer molecular dynamics and instanton theory calculations.

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  1. These authors contributed equally: Yiqiang Liu, Lijie Liu.

Authors and Affiliations

  1. State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China

    Yiqiang Liu, Lijie Liu, Yanlin Fu, Haotian Jiang, Hao Wu, Yue Liu, Xiaoxiao Lu, Xiaohu Zhou, Hongwei Li, Bina Fu, Wenrui Dong, Dong H. Zhang & Xueming Yang

  2. School of Materials Science and Engineering, Anyang Institute of Technology, Anyang, China

    Yiqiang Liu

  3. Department of Chemical Physics, University of Science and Technology of China, Hefei, China

    Lijie Liu, Haotian Jiang, Yue Liu & Xingan Wang

  4. University of Chinese Academy of Sciences, Beijing, China

    Hongwei Li, Bina Fu, Wenrui Dong & Dong H. Zhang

  5. Department of Chemistry, University of Colorado, Boulder, CO, USA

    Rex T. Skodje

  6. Hefei National Laboratory, Hefei, China

    Xingan Wang, Bina Fu, Wenrui Dong, Dong H. Zhang & Xueming Yang

  7. Department of Chemistry and Center for Advanced Light Source Research, College of Science, Southern University of Science and Technology, Shenzhen, China

    Xueming Yang

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Contributions

X.Y., D.H.Z., W.D. and B.F. conceived and supervised the research. Yi.L., H.J., Yu.L., X.Z., H.L., X.W. and W.D. performed the experiments. Yi.L., H.J., Yu.L., X.Z., H.L., X.W., W.D. and X.Y. performed the experimental data analysis and interpretation. L.L., Y.F., H.W. and B.F. performed the potential energy surface construction and dynamics simulations. L.L., Y.F., H.W., X.L., R.T.S., B.F. and D.H.Z. discussed the theoretical results and analysis. X.Y., W.D. and B.F. wrote the paper, with contributions from all authors. All authors contributed to discussions about the content of the paper.

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Correspondence to Bina Fu, Wenrui Dong, Dong H. Zhang or Xueming Yang.

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Liu, Y., Liu, L., Fu, Y. et al. Reactivity of syn-CH3CHOO with H2O enhanced through a roaming mechanism in the entrance channel. Nat. Chem. 17, 897–903 (2025). https://doi.org/10.1038/s41557-025-01798-9

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