大气自氧化中的立体选择性。
Stereoselectivity in Atmospheric Autoxidation.
作者信息
Møller Kristian H, Praske Eric, Xu Lu, Crounse John D, Wennberg Paul O, Kjaergaard Henrik G
机构信息
Department of Chemistry , University of Copenhagen , DK-2100 Copenhagen Ø , Denmark.
Division of Chemistry and Chemical Engineering , California Institute of Technology , Pasadena , California 91125 , United States.
出版信息
J Phys Chem Lett. 2019 Oct 17;10(20):6260-6266. doi: 10.1021/acs.jpclett.9b01972. Epub 2019 Oct 3.
We show that the diastereomers of hydroxy peroxy radicals formed from OH and O addition to C2 and C3, respectively, of crotonaldehyde (CHCHCHCHO) undergo gas-phase unimolecular aldehydic hydrogen shift (H-shift) chemistry with rate coefficients that differ by an order of magnitude. The stereospecificity observed here for crotonaldehyde is general and will lead to a significant diastereomeric-specific chemistry in the atmosphere. This enhancement of specific stereoisomers by stereoselective gas-phase reactions could have widespread implications given the ubiquity of chirality in nature. The H-shift rate coefficients calculated using multiconformer transition state theory (MC-TST) agree with those determined experimentally using stereoisomer-specific gas-chromatography chemical ionization mass spectroscopy (GC-CIMS) measurements.
我们表明，由羟基（OH）和氧（O）分别加成到巴豆醛（CHCHCHCHO）的C2和C3上形成的羟基过氧自由基的非对映异构体，会发生气相单分子醛氢转移（H-转移）反应，其速率系数相差一个数量级。此处观察到的巴豆醛的立体特异性具有普遍性，将导致大气中显著的非对映异构体特异性化学过程。鉴于自然界中手性的普遍存在，通过立体选择性气相反应增强特定立体异构体可能具有广泛的影响。使用多构象体过渡态理论（MC-TST）计算的H-转移速率系数与使用立体异构体特异性气相色谱化学电离质谱（GC-CIMS）测量实验确定的速率系数一致。
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