2 research outputs found
Kinetics of the CH<sub>3</sub> + C<sub>5</sub>H<sub>5</sub> Reaction: A Theoretical Study
Formation of fulvene and benzene
through the reaction of cyclopentadienyl
(C<sub>5</sub>H<sub>5</sub>) with methyl radical (CH<sub>3</sub>)
and consequent dissociation of its primary C<sub>6</sub>H<sub>7</sub> products has been studied using ab initio and theoretical kinetics
calculations. The potential energies and geometries of all involved
species have been computed at the CCSD(T)-F12/cc-pVTZ-f12//B2PLYPD3/aug-cc-pVDZ
level theory. Multichannel/multiwell RRKM-Master Equation calculations
have been utilized to produce phenomenological pressure- and temperature-dependent
absolute and individual-channel rate constants for various reactions
at the C<sub>6</sub>H<sub>8</sub> and C<sub>6</sub>H<sub>7</sub> potential
energy surfaces. The kinetic scheme combining the primary and secondary
reactions has been used to generate the overall rate constants for
the production of fulvene and benzene and their branching ratios.
Analyses of the kinetic data revealed that at low pressures (0.01
atm) benzene formation prevails, with branching ratios exceeding 60%,
whereas at the highest pressure (100 atm) fulvene formation is prevalent,
with the branching ratio of benzene being lower than 40%. At intermediate
pressures (1 and 10 atm) the two product channels compete and fulvene
formation is preferable at temperatures above 1600 K. The results
demonstrate that a five-member ring can be efficiently transformed
into an aromatic six-member ring by methylation and corroborate the
potentially important role of the methyl radical in the mechanism
of PAH growth where CH<sub>3</sub> additions alternate with H abstractions
and acetylene additions