ON THE MECHANISM OF THE REACTION OF CF3 RADICALS WITH C6F5CL IN THE TEMPERATURE-RANGE 318-473 K

The gas-phase reaction of CF3 radicals, generated by photolysis of per fluoroacetic anhydride, with C6F5Cl was studied in the temperature ran ge 318-473 K and total pressures between 23 and 41 Torr. CF3 radicals react with C6F5Cl according to the following mechanism: CF3 + C6F5Cl r eversible arrow(kadd) CF3C6F5Cl (1), (-1) CF3 + CF3C6F5Cl --> CF3Cl C6F5CF3 (2) 2CF(3) -->(kc) C2F6 (3) It was found that the addition rea ction becomes reversible above 390 K. The addition rate parameters can be summarized in the following equation: log [(k(add)/k(c)(1/2)) mol( -1/2) cm(3/2) s(-1/2)] = (4.46 +/- 0.10) - (22.48 +/- 0.70)/theta wher e theta = 2.303 R T kJ mol(-1) and k(c) is the recombination constant of CF3 radicals. A correlation between log (k(add)/k(c)(1/2)) and the ionization potentials for 15 aromatic compounds was found.