Addition of free radicals to unsaturated systems. Part 24. Kinetics and mechanism of the gas-phase thermal reactions of trifluoroiodomethane with propene

Abstract

The gas-thermal addition of trifluoroiodomethane to propene, at temperatures of 533–583 K, reactant ratios from 1 : 1 to 4 : 1, and total pressures of 100–300 mmHg, is shown to be a free-radical chain reaction with the kinetic equation as shown below. It is concluded that initiation is by the reaction of d[adduct]//_dt=k₈[I₂]^0.25[CF₃I]^1.09[C₃H₆]^0.41 iodine atoms, in thermal equilibrium with molecular iodine, with trifluoroiodomethane, and termination is predominantly by reactions involving trifluorobutyl radicals. The Arrhenius parameters found for k₈ are discussed in terms of those for the elementary reactions involved on the basis of the proposed mechanism.