Abstract: | 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 (kt) is pressure-independent, whereas those for the formation of C6H5C2H (kb) and the C6H5C2H2 adduct (kc) 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 and all in units of cm3/s. The latter equation effectively represents the two sets of experimental data. © 1994 John Wiley & Sons, Inc. |