Iyer Siddharth, Kumar Avinash, Savolainen Anni, Barua Shawon, Daub Christopher, Pichelstorfer Lukas, Roldin Pontus, Garmash Olga, Seal Prasenjit, Kurtén Theo, Rissanen Matti
Aerosol Physics Laboratory, Tampere University, FI-33101, Tampere, Finland.
Department of Chemistry, University of Helsinki, P.O. Box 55, FI-00014, Helsinki, Finland.
Nat Commun. 2023 Aug 17;14(1):4984. doi: 10.1038/s41467-023-40675-2.
The oxidation of aromatics contributes significantly to the formation of atmospheric aerosol. Using toluene as an example, we demonstrate the existence of a molecular rearrangement channel in the oxidation mechanism. Based on both flow reactor experiments and quantum chemical calculations, we show that the bicyclic peroxy radicals (BPRs) formed in OH-initiated aromatic oxidation are much less stable than previously thought, and in the case of the toluene derived ipso-BPRs, lead to aerosol-forming low-volatility products with up to 9 oxygen atoms on sub-second timescales. Similar results are predicted for ipso-BPRs formed from many other aromatic compounds. This reaction class is likely a key route for atmospheric aerosol formation, and including the molecular rearrangement of BPRs may be vital for accurate chemical modeling of the atmosphere.
芳烃的氧化对大气气溶胶的形成有显著贡献。以甲苯为例，我们证明了氧化机制中存在分子重排通道。基于流动反应器实验和量子化学计算，我们表明在OH引发的芳烃氧化过程中形成的双环过氧自由基（BPRs）比之前认为的稳定性要低得多，并且在甲苯衍生的本位BPRs的情况下，会在亚秒级时间尺度上生成含有多达9个氧原子的形成气溶胶的低挥发性产物。由许多其他芳烃化合物形成的本位BPRs预计也会有类似结果。这类反应可能是大气气溶胶形成的关键途径，将BPRs的分子重排纳入考虑可能对大气化学的精确建模至关重要。
