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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Intramolecular Hydrogen Bonding and Double H-Atom Transfer in Peroxy and Alkoxy Radicals from Isoprene
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Intramolecular Hydrogen Bonding and Double H-Atom Transfer in Peroxy and Alkoxy Radicals from Isoprene

机译：异戊二烯的过氧和烷氧基自由基中的分子内氢键和双H原子转移

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摘要

Quantum mechanical calculations were used to determine the structure and stability of second-generation peroxy and alkoxy radicals formed in the atmospheric degradation of isoprene (2-methyl-1,3-butadiene). Certain of these radicals exhibit a novel hydrogen bonding motif, consisting of two intramolecular hydrogen bonds. The hydrogen bonds are donated in series, with an enol group donating a hydrogen bond to a -CH2OH group, which donates in turn to the oxygen radical center. This hydrogen bonding motif opens a new reaction pathway: the simultaneous transfer of two H-atoms across the hydrogen bonds with a barrier of only ～5 kcal/mol in the alkoxy radicals, but ～20 kcal/mol in the peroxy radicals. Rate constants for these reactions were calculated, and the effects of tunneling on the rate constant were examined. All species and reactions were analyzed at the B3LYP/6-311G(2df,2p) level of theory; the transition states for the double H-atom transfer reactions were also studied using the MPW1K functional and the CBS-QB3 method. Similar chemistry is possible for alkoxy and peroxy radicals derived from other volatile organic compounds of atmospheric interest.
机译：量子力学计算被用来确定异戊二烯（2-甲基-1,3-丁二烯）在大气中降解时形成的第二代过氧和烷氧基的结构和稳定性。这些自由基中的某些表现出由两个分子内氢键组成的新颖的氢键基序。氢键是串联提供的，烯醇基团将氢键提供给-CH2OH基团，后者又提供给氧自由基中心。这种氢键基序开辟了一条新的反应途径：两个氢原子同时通过氢键转移，在烷氧基自由基中的阻隔仅为〜5 kcal / mol，而在过氧自由基中的阻隔仅为〜20 kcal / mol。计算这些反应的速率常数，并研究隧穿对速率常数的影响。在B3LYP / 6-311G（2df，2p）的理论水平上分析了所有物种和反应;还使用MPW1K功能和CBS-QB3方法研究了双H原子转移反应的过渡态。对于衍生自大气中其他挥发性有机化合物的烷氧基和过氧自由基，类似的化学反应也是可能的。

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