Rapid Hydrogen Shift Scrambling in Hydroperoxy-Substituted Organic Peroxy Radicals

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• 作者：Solvejg J?rgensen ; Hasse C. Knap ; Rasmus V. Otkj?r ; Annesofie M. Jensen ; Mette L. H. Kjeldsen ; Paul O. Wennberg ; Henrik G. Kjaergaard
• 刊名：Journal of Physical Chemistry A
• 出版年：2016
• 出版时间：January 21, 2016
• 年：2016
• 卷：120
• 期：2
• 页码：266-275
• 全文大小：506K
• ISSN：1520-5215

文摘

Using quantum mechanical calculations, we have investigated hydrogen shift (H-shift) reactions in peroxy radicals derived from the atmospheric oxidation of 1-pentene (CH₂═CHCH₂CH₂CH₃) and its monosubstituted derivatives. We investigate the peroxy radicals, HOCH₂CH(OO)CR₁HCH₂CH₃, HOCH₂CH(OO)CH₂CR₁HCH₃, and HOCH₂CH(OO)CH₂CH₂CR₁H₂, where the substituent R₁ is an alcoholic (OH), a hydroperoxy (OOH), or a methoxy (OCH₃) group. For peroxy radicals with an OOH substituent, the H-shift reaction from the hydrogen atom on the OOH group to the OO group is extremely fast. We find that the rate constants of this type of H-shift reactions are greater than 10³ s^–1 for both the forward and the reverse reactions. It leads to the formation of two different radical isomers that react through different reaction mechanisms and yield different products. These very fast H-shift reactions are much faster than the reactions with NO and HO₂ under most atmospheric conditions and must be included in the atmospheric modeling of volatile organic compounds where hydroperoxy peroxy radicals are formed.