General Mechanism for Sulfate Radical Addition to Olefinic Volatile Organic Compounds in Secondary Organic Aerosol
General Mechanism for Sulfate Radical Addition to Olefinic Volatile Organic Compounds in Secondary Organic Aerosol
复制标题
二次有机气溶胶中烯烃挥发性有机化合物硫酸根加成的一般机制
DOI：
10.1021/acs.est.0c05256
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发表时间：
2021
影响因子：
11.4
通讯作者：
Elrod, Matthew J.
中科院分区：
文献类型：
--
作者：
Ren, He;Sedlak, Jane A.;Elrod, Matthew J.
以前的实验室研究表明，在环境二次有机气溶胶(SOA)中检测到的一些有机硫酸盐可能是硫酸盐与烯烃类生物挥发性有机化合物(BVOCs)的加成反应。然而，这些研究提出了相互矛盾的反应产物，可能是因为实验室的溶解氧水平没有准确地反映大气条件。此外，这些研究使用的分析方法不能明确地识别和量化特定结构的产品。在这里，我们描述了一种方法，该方法允许研究硫酸盐自由基与几种烯烃前体的反应，包括烯丙醇(AA)、甲基乙烯基酮(MVK)、2-甲基-3-丁烯-2-醇(MBO)和甲基丙烯醛(MA)，通过仔细控制溶解氧水平，并使用异构体特定的核磁共振(NMR)方法来确定和定量反应产物。发展了每一种烯烃前驱体的特定反应机理，以及可用于预测任何烯烃的硫酸盐自由基反应路径的通用机理。产物产率结果表明，AA、MVK、MBO和MA的碳链断裂途径占主导地位，分别为61、83、79和100%。观测到的几种有机硫酸盐产物也在SOA的野外观测中被检测到，这表明这一机制与大气中的潜在相关性。
Previous laboratory studies have suggested that sulfate radical addition to olefinic biogenic volatile organic compounds (BVOCs) is a potential formation mechanism for some organosulfates detected in ambient secondary organic aerosol (SOA). However, these studies propose conflicting reaction products, possibly because laboratory dissolved oxygen levels did not accurately reflect atmospheric conditions. Additionally, these studies used analytical methods that could not definitively identify and quantify the structurally specific products. Here, we describe a method that allows for the study of the reaction of sulfate radicals and several olefinic precursors, including allyl alcohol (AA), methyl vinyl ketone (MVK), 2-methyl-3-buten-2-ol (MBO), and methacrolein (MA), with careful control of dissolved oxygen levels and using the isomer-specific nuclear magnetic resonance (NMR) method to definitively identify and quantify the reaction products. Specific mechanisms for each olefinic precursor were developed, as well as a generalized mechanism that can be used to predict the sulfate radical reaction pathways for any olefin. The product yield results indicate that this mechanism is dominated by carbon backbone fragmentation pathways: 61, 83, 79, and 100% for AA, MVK, MBO, and MA, respectively. Several of the observed organosulfate products have also been detected in field observations of SOA, which indicates the potential relevance of this mechanism in the atmosphere.