posted on 2016-03-01, 00:00authored byGianmarco Vanuzzo, Nadia Balucani, Francesca Leonori, Domenico Stranges, Stefano Falcinelli, Astrid Bergeat, Piergiorgio Casavecchia, Ilaria Gimondi, Carlo Cavallotti
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.