Rate constants for the recombination of CCl 3 radicals and for their reactions with Cl, Cl 2 and HCl in the gas phase

The gas-phase photochlorination of CHCl3 has been investigated between 303.2 and 425.5° K. The reaction was followed both by a conventional and a mass spectrometric technique. Rate measurements in steady light lead to log10(k3/K½8)=–5,000/4.576 T+3.91, (i), and log10(k3k2/k7)½=–3,700/4.576 T+3.60 (ii), where k2, k3, k7 and k8 refer to Cl + CHCl3→ CCl3+ HCl (2), CCl3+ Cl2→ Cl + CCl4(3), Cl + CCl3→ CCl4(7), 2CCl3→ C2Cl6(8), Rate measurements in intermittent light give log10k3=–5,000/4.576 T+8.74, (iii) which combined with eqn. (i) and (ii), and the known value of k2 yields log10k7= 10.8 and log10k8= 9.6 6, indenpendent temperature. Using the values of K,2 and K,3 and thermodynamic data, one calculates log10K4=–11,300/4.576T+8.65 and log10k5=–20,000/4.576 T+10.93, for the reverse of reactions (2) and (3) respectively. All rate constants are given in mole–1 1. sec–1.