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The rate constant for the combination of trichloromethyl radicals in the gas phase has been measured by applying the rotating sector technique to the gas phase carbon tetrachloride–cyclohexane photochemical system. A temperature-independent rate constant, k5, of 3.9 ± 1.0 × 1012 cc mole−1 sec−1 was found. Arrhenius parameters for the reaction were found to be given by the expression log k4 = 11.79 – (10,700/2.3 RT).

The rate constant for the combination of 1,1-dichloro-2,2,2-trifluoroethyl radicals in the gas phase has been measured by applying the rotating sector technique to the 1,1,1-trichloro-2,2,2-trifluoroethane–cyclohexane photochemical system. The combination rate constant, k5, was found to be 6.6 × 1012 cc mole−1 sec−1. Arrhenius parameters for the reaction, are given by the expression log k4 = 11.81 – (9700/2.3RT).

The gas phase photolysis of CCl4 in the presence of several alkanes has been used to obtain Arrhenius parameters for the abstraction of hydrogen atoms by the CCl3 radical: The following log k4 values were obtained: Text Table Text. RH log k4 c-C5H10, n-C6H14 2,3-Dimethylbutane c-C7H14 Methylcyclohexane c-C8H16 The results are compared to those for CH3 and CF3 radicals.

The gas phase photolysis of CF3CCl3 in the presence of several alkanes has been used to obtain Arrhenius parameters for the abstraction of hydrogen atoms by the CF3CCl2 radical: Activation energies of 9.6 and 8.0 kcal/mole are found for abstraction from secondary and tertiary C–H bonds, respectively. The Arrhenius parameters are compared to those for CCl3 and CF3 radicals.

The thermal decomposition of hexachloroethane in the presence of chlorine has been studied over the temperature range 340-400°C and a pressure range of 0.5°2.5 atm. The rate of the unimolecular CC bond spliting reaction can be described by the Arrhenius equation Comparison of these rate data with thermodynamic data suggests a combination rate for CCl3 radicals which is consistent with earlier measurements.