Rate constants for the recombination of CCl3 radicals and for their reactions with Cl, Cl2 and HCl in the gas phase

Abstract

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/K^½₈)=–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.