Production and Fate of C4 Dihydroxycarbonyl Compounds from Isoprene Oxidation
Production and Fate of C4 Dihydroxycarbonyl Compounds from Isoprene Oxidation
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DOI：
10.1021/acs.jpca.5b10335
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发表时间：
2016-01-14
影响因子：
2.9
通讯作者：
Wennberg, Paul O.
中科院分区：
文献类型：
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作者：
Bates, Kelvin H.;Nguyen, Tran B.;Wennberg, Paul O.
异戊二烯环氧二醇（IEPOX）在原始（低氮氧化物）环境中作为大气异戊二烯氧化的第二代产物大量生成。IEPOX因其能够形成二次有机气溶胶而受到广泛关注，但其在气相中的归宿以及其氧化产物的归宿在很大程度上仍未被探索。在本研究中，合成了三种分子式为C₄H₈O₃的二羟基羰基化合物，它们是IEPOX氧化的假定产物，以确定它们从IEPOX生成的异构体特异性产率。我们发现3,4 - 二羟基 - 2 - 丁酮（DHBO）分别占顺式 - 和反式 - β - IEPOX产物的43%和36%，并且是迄今为止通过这种机制产生的最丰富的C₄H₈O₃二羟基羰基化合物。在297 K时，发现OH与DHBO反应的速率系数为1.10×10⁻¹¹ cm³·分子⁻¹·s⁻¹，形成两种具有相同分子式C₄H₆O₃且产率为1的羟基二羰基化合物。本研究结果与实地观测结果进行了比较，并用于提出IEPOX氧化的多代机制。最后，使用化学传输模型GEOS - Chem进行的全球模拟表明，C₄H₈O₃二羟基羰基化合物及其氧化产物在大气中广泛存在，并估计C₄H₈O₃二羟基羰基化合物的全球年生产量为54 Tg·y⁻¹，主要是DHBO。
Isoprene epoxydiols (IEPOX) are formed in high yield as second-generation products of atmospheric isoprene oxidation in pristine (low-NO) environments. IEPOX has received significant attention for its ability to form secondary organic aerosol, but the fate of IEPOX in the gas phase, and those of its oxidation products, remains largely unexplored. In this study, three dihydroxycarbonyl compounds with molecular formula of C4H8O3, putative products of IEPOX oxidation, are synthesized to determine their isomer-specific yields from IEPOX. We find that 3,4-dihydroxy-2-butanone (DHBO) comprises 43% and 36% of the products from cis- and trans-beta-IEPOX, respectively, and is by far the most abundant C4H8O3 dihydroxycarbonyl compound produced by this mechanism. OH is found to react with DHBO with a rate coefficient of 1.10 x 10(-11) cm(3) molecule(-1) s(-1) at 297 K, forming two hydroxydicarbonyl compounds that share the molecular formula C4H6O3 with unitary yield. The results of this study are compared with field observations and used to propose a multigenerational mechanism of IEPOX oxidation. Finally, global simulations using GEOS-Chem, a chemical transport model, show that the C4H8O3 dihydroxycarbonyl compounds and their oxidation products are widespread in the atmosphere and estimate annual global production of C4H8O3 dihydroxycarbonyls to be 54 Tg y(-1), primarily as DHBO.