Chemical activation and unimolecular dissociation pathway kinetic analysis is presented on addition of radicals H, O, OH, and HO 2 to one of the two types of unsaturated carbons on cyclopentadiene. Addition of H atom or OH radical at the 1 position forms an allylic radical, which can break the weaker (allylic) bond, opening the 5-carbon9carbon carbon ring and forming a resonance stabilized radical. Addition at the 2 position is less exothermic and forms a secondary radical, which can break a bond to form carbon9carbon a vinylic radical. The vinylic radical, if formed will rapidly react with O2 or decompose, β€ Scission. Addition at the 2 position usually results in reverse reaction (dissociation back to the reactants) O (3P) addition to the two types of unsaturated carbons on cyclopentadiene will form two diradical isomers which will quickly decompose to H atom plus cyclopentenone-yl radicals, both of these cyclopentenone-yl radicals will undergo β€ Scission to form stable cyclopentadienone and H atom.
HO 2 addition to the unsaturated carbons on cyclopentadiene can form the cyclopentenyl (allylic) radical plus O 2 as products through intramolecular isomerization (H Shift) and then dissociation.
Thermochemical property data for intermediate species along with rate constants for these radical addition reactions to cyclopentadiene and the decomposition/isomerization reactions of the adducts are estimated. Rate constants for each channel are calculated using bimolecular quantum Rice Ramsperger Kassel, QRRK, for k(E) with a modified strong collision analysis for fall off. Rate constants are presented over a range of pressure and temperature. Modeling results are compared to the limited literature data available for validation, i.e., to species profiles for appropriate reaction systems, where cyclopentadiene is a key intermediate.
Rate constants on abstraction of the resonance stabilized H from the cyclopentadiene ring are also estimated.
Major (vida infra) reaction channels and kinetic parameters