Kinetic Study of the Reaction of Chlorine Atoms with CF3I and the Reactions of CF3 Radicals with O2, Cl2 and NO at 296 K

Article abstract of DOI:10.1002/kin.550270302

The kinetics of the gas-phase reaction of Cl atoms with CF3I have been studied relative to the reaction of Cl atoms with CH4 over the temperature range 271 - 363 K.Using k(Cl + CH4) = 9.6*10^-12 exp(-2680/RT) cm³ molecule^-1 s^-1, we derive k(Cl + CF3I) = 6.25*10^-11 exp(-2970/RT) in which E_a has units of cal mol^-1.CF3 radicals are produced from the reaction of Cl with CF3I in a yield which was indistinguishable from 100percent.Other relative rate constant ratios measured at 296 K during these experiments were k(Cl + C2F5I)/k(Cl + CF3I) = 11.0 +/- 0.6 and k(Cl + C2F5I) /k(Cl + C2H5Cl) = 0.49 +/- 0.02.The reaction of CF3 radicals with Cl2 was studied relative to that with O2 at pressures from 4 to 700 torr of N2 diluent.By using the published absolute rate constants for k(CF3 + O2) at 1-10 torr to calibrate the pressure dependence of these relative rate constants, values of the low- and high-pressure limiting rate constants have been determined at 296 K using a Troe expression: k₀(CF3 + O2) = (4.8 +/- 1.2)*10^-29 cm⁶ molecule^-2 s^-1; k_infinite(CF3 + O2) = (3.95 +/- 0.25)*10^-12 cm³ molecule^-1 s^-1; F_c = 0.46.The value of the rate constant k(CF3 + Cl2) was determined to be (3.5 +/- 0.4)*10^-14 cm³ molecule^-1 s^-1 at 296 K.The reaction of Cl atoms with CF3I is a convenient way to prepared CF3 radicals for laboratory study.