Unimolecular and water reactions of oxygenated and unsaturated Criegee intermediates under atmospheric conditions.
Unimolecular and water reactions of oxygenated and unsaturated Criegee intermediates under atmospheric conditions.
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含氧和不饱和 Criegee 中间体在大气条件下的单分子和水反应。
DOI：
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发表时间：
2022
期刊：
影响因子：
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通讯作者：
A. Wahner
中科院分区：
文献类型：
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作者：
L. Vereecken;A. Novelli;A. Kiendler‐Scharr;A. Wahner
不饱和烃（VOCs）的臭氧分解是大气中主要的氧化过程之一。形成的稳定的Criegee中间体（SCI）是高活性的氧化物质，可能影响HOx、NOx和SOx循环，并通过产生低挥发性的含氧化合物影响气溶胶的形成。目前对主要由初次排放的VOCs形成的SCI的认识较多，但对氧合SCI的反应性了解甚少。在这项工作中，我们提出了大量不饱和和含氧SCI的理论动力学研究，涵盖了与SCI羰基氧化物部分相关的各种立体和位点特异性取代的C / C、OH、OR、OOH、OOOH、COOH、COOR和ONO2官能团。介绍了几种新的反应类型，其中最重要的是OH， OOH和COOH基团的快速分子内插入反应，或与COOH基团形成二次臭氧，形成环氧合物质；这些反应类别使人想起类似的双分子反应。对H2O分子的反应进行了同样的研究，发现这些环化反应可以被催化，预测的速率系数接近碰撞极限。理论数据用于扩展由Vereecken et al.（2017）提出的构效关系（sar），预测主要的单分子反应类别和速率，以及与H2O和（H2O）2的反应速率。这些sar涵盖了超过300个SCI类别，超过40个取代类别。讨论了这些sar的有效性，并对进一步改进进行了展望。氧化性SCI的寿命通常较短，这表明臭氧分解次生氧化性VOCs不太可能产生超过104 cm-3的SCI环境浓度，但会强烈促进氧化性VOCs的原位形成。
Ozonolysis of unsaturated hydrocarbons (VOCs) is one of the main oxidation processes in the atmosphere. The stabilized Criegee intermediates (SCI) formed are highly reactive oxygenated species that potentially influence the HOx, NOx and SOx cycles, and affect aerosol formation by yielding low-volatility oxygenated compounds. The current knowledge spans mostly SCI formed from primary emitted VOCs, but little is known about the reactivity of oxygenated SCI. In this work we present a theoretical kinetic study of a large number of unsaturated and oxygenated SCI, covering CC, OH, OR, OOH, OOOH, COOH, COOR, and ONO2 functionalities at various stereo- and site-specific substitutions relative to the SCI carbonyl oxide moiety. Several novel reaction types are covered, the most important of which are fast intramolecular insertion reactions in OH, OOH and COOH groups, or secondary ozonide formation with a COOH group, forming cyclic oxygenated species; these reaction classes are reminiscent of the analogous bimolecular reactions. The reaction with H2O molecules was likewise studied, finding that these cyclisation reactions can be catalysed, with predicted rate coefficients nearing the collision limit. The theoretical data is used to extend the structure-activity relationships (SARs) proposed by Vereecken et al. (2017), predicting the dominant unimolecular reaction class and rate, and the rates for reaction with H2O and (H2O)2. The SARs cover over 300 SCI categories with over 40 substituent categories. The validation of these SARs is discussed, and an outlook is given for further improvement. The generally short lifetime of oxygenated SCI suggests that ozonolysis of secondary, oxygenated VOCs is unlikely to yield ambient concentrations of SCI exceeding 104 cm-3 but will contribute strongly to the in situ formation of oxygenated VOCs.