Isomer-Specific Chemistry in the Propyne and Allene Reactions with Oxygen Atoms: CH3CH + CO versus CH2CH2 + CO Products

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• 作者：Gianmarco Vanuzzo ; Nadia Balucani ; Francesca Leonori ; Domenico Stranges ; Stefano Falcinelli ; Astrid Bergeat ; Piergiorgio Casavecchia ; Ilaria Gimondi ; Carlo Cavallotti
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2016
• 出版时间：March 17, 2016
• 年：2016
• 卷：7
• 期：6
• 页码：1010-1015
• 全文大小：411K
• ISSN：1948-7185

文摘

We report direct experimental and theoretical evidence that, under single-collision conditions, the dominant product channels of the O(³P) + propyne and O(³P) + allene isomeric reactions lead in both cases to CO formation, but the coproducts are singlet ethylidene (¹CH₃CH) and singlet ethylene (CH₂CH₂), respectively. These data, which settle a long-standing issue on whether ethylidene is actually formed in the O(³P) + propyne reaction, suggest that formation of CO + alkylidene biradicals may be a common mechanism in O(³P) + alkyne reactions, in contrast to formation of CO + alkene molecular products in the corresponding isomeric O(³P) + diene reactions, either in combustion or other gaseous environments. These findings are of fundamental relevance and may have implications for improved combustion models. Moreover, we predict that the so far neglected ¹CH₃CH + CO channel is among the main reaction routes also when the C₃H₄O singlet potential energy surface is accessed from the OH + C₃H₃ (propargyl) entrance channel, which are radical species playing a key role in many combustion systems.