The reaction of n- and i-C4H5 radicals with acetylene

In this article, we discuss the reactions of i-C4H5 and n-C4H5 with acetylene. Both have been proposed as possible cyclization steps, forming benzene or fulvene, in rich flames burning aliphatic fuels. The relevant parts of the potential energy surface were determined from rQCISD(T) calculations extrapolated to the infinite-basis-set limit. Using this information in a Rice-Ramsperger-Kassel-Marcus-based master equation, we have calculated thermal rate coefficients and product distributions for both reactions as a function of temperature and pressure. The results are cast in forms that can be used in modeling, and the implications of the results for flame chemistry are discussed.