Vanuzzo Gianmarco, Balucani Nadia, Leonori Francesca, Stranges Domenico, Falcinelli Stefano, Bergeat Astrid, Casavecchia Piergiorgio, Gimondi Ilaria, Cavallotti Carlo
Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia , 06123 Perugia, Italy.
Dipartimento di Chimica, Materiali e Ingegneria Chimica "Giulio Natta", Politecnico di Milano , 20131 Milano, Italy.
J Phys Chem Lett. 2016 Mar 17;7(6):1010-5. doi: 10.1021/acs.jpclett.6b00262. Epub 2016 Mar 4.
We report direct experimental and theoretical evidence that, under single-collision conditions, the dominant product channels of the O((3)P) + propyne and O((3)P) + allene isomeric reactions lead in both cases to CO formation, but the coproducts are singlet ethylidene ((1)CH3CH) and singlet ethylene (CH2CH2), respectively. These data, which settle a long-standing issue on whether ethylidene is actually formed in the O((3)P) + propyne reaction, suggest that formation of CO + alkylidene biradicals may be a common mechanism in O((3)P) + alkyne reactions, in contrast to formation of CO + alkene molecular products in the corresponding isomeric O((3)P) + 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 (1)CH3CH + 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.
