Absolute rate constant for the reaction of phenyl radical with acetylene

Article abstract of DOI:10.1002/kin.550261105

The absolute rate constant for the reaction of phenyl radical with acetylene has been measured at 20 torr total pressure in the temperature range of 297 to 523 K using the cavity-ring-down technique. These new kinetic data could be quantitatively correlated with the data obtained earlier with a relative rate method under low-pressure (10^-3-10^-2 torr) and high-temperature (1000-1330 K) conditions. These kinetic data were analyzed in terms of the RRKM theory employing the thermochemical and molecular structure data computed with the BAC-MP4 technique. The calculated results reveal that the total rate constant for the C₆H₅+C₂H₂ reaction (k_t) is pressure-independent, whereas those for the formation of C₆H₅C₂H (k_b) and the C₆H₅C₂H₂ adduct (k_c) are strongly pressure-dependent. A least-squares analysis of the calculated values for 300-2000 K at the atmospheric pressure of N₂ or Ar can be given by: k_b = 9.5×10^-42T^9.33 exp(-1,713/T); k_c = 1.8×10^-7T^-1.63 exp(-2,711/T); and k_t = 4.1×10^-18T^1.77 exp(-1,152/T), all in units of cm³/s. The latter equation effectively represents the two sets of experimental data.