乙烯气相臭氧分解中最简单的克里奇中间体CH2OO的观测。
Observation of the simplest Criegee intermediate CH2OO in the gas-phase ozonolysis of ethylene.
作者信息
Womack Caroline C, Martin-Drumel Marie-Aline, Brown Gordon G, Field Robert W, McCarthy Michael C
机构信息
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA.
出版信息
Sci Adv. 2015 Mar 6;1(2):e1400105. doi: 10.1126/sciadv.1400105. eCollection 2015 Mar.
Ozonolysis is one of the dominant oxidation pathways for tropospheric alkenes. Although numerous studies have confirmed a 1,3-cycloaddition mechanism that generates a Criegee intermediate (CI) with form R1R2COO, no small CIs have ever been directly observed in the ozonolysis of alkenes because of their high reactivity. We present the first experimental detection of CH2OO in the gas-phase ozonolysis of ethylene, using Fourier transform microwave spectroscopy and a modified pulsed nozzle, which combines high reactant concentrations with rapid sampling and sensitive detection. Nine other product species of the O3 + C2H4 reaction were also detected, including formaldehyde, formic acid, dioxirane, and ethylene ozonide. The presence of all these species can be attributed to the unimolecular and bimolecular reactions of CH2OO, and their abundances are in qualitative agreement with published mechanisms and rate constants.
臭氧分解是对流层烯烃的主要氧化途径之一。尽管众多研究已证实一种1,3 - 环加成机制，该机制会生成具有R1R2COO形式的Criegee中间体（CI），但由于其高反应活性，在烯烃的臭氧分解过程中从未直接观测到小分子的CIs。我们利用傅里叶变换微波光谱法以及一种改良的脉冲喷嘴，首次在乙烯的气相臭氧分解实验中检测到了CH2OO，该喷嘴将高反应物浓度与快速采样和灵敏检测相结合。还检测到了O3 + C2H4反应的其他九种产物，包括甲醛、甲酸、二氧杂环丙烷和乙烯臭氧化物。所有这些物种的存在可归因于CH2OO的单分子和双分子反应，并且它们的丰度与已发表的反应机理和速率常数在定性上是一致的。
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