Addition reactions of the phenyl radical with C₂H₂ and C₂H₄: Detailed kinetics and mechanism with first-principles calculations

The C₆H₅ + C₂H₂/C₂H₄ addition reactions and subsequent transformations were studied within a framework of the G2M composite method. The detailed search on the corresponding potential energy surfaces revealed that chemically activated adducts could undergo several isomerization pathways in competition with well-known deactivation and H-elimination channels. Thus formed isomeric (vinylic/aliphatic, aromatic and bicyclic) C₈H₇/C₈H₉ radicals could serve as active agents in the mass growth reactions with C₂H₂, C₂H₄, and other light unsaturated hydrocarbons and radicals. The latter processes are relevant to the PAH formation in hydrocarbon combustion. The mechanism of the C₆H₅ + C₂H₂/C₂H₄ addition reactions in different regimes and the implications to larger scale combustion modeling were discussed. Original is an abstract.