Jump to main content
Jump to site search

Issue 0, 1973
Previous Article Next Article

Absolute rate constants for elementary reactions in the chlorination of CH4, CD4, CH3Cl, CH2Cl2, CHCl3, CDCl3 and CBrCl3

Abstract

The rates of reactions of Cl2P atoms with methane, and with a series of substituted methanes, have been measured using mass spectrometric analysis of molecular reactant consumption in the presence of excess Cl atoms, with pseudo first order kinetic analysis; this approach minimizes secondary reactions and the problem of reaction stoichiometries. The following rate constants were obtained for Cl + RH reactions: log10(kCH4/cm3 molecule–1 s–1)=(–10.294 ± 0.043)–(778 ± 16) K/T, 300–686 K; log10(kCH3Cl/cm3 molecule–1 s–1)=(–9.673 ± 0.087)–(776 ± 30) K/T, 300–604 K; log10(kCH2Cl2/cm3 molecule–1 s–1)=(–10.078 ± 0.074)–(629 ± 26) K/T, 298–621 K; log10(kCHCl3/cm3 molecule–1 s–1)=(–10.480 ± 0.051)–(599 ± 19) K/T, 297–652 K; log10(kCBrCl3/cm3 molecule–1 s–1)=–12.64 ± 0.08, 652 K. The correlations of these results with data from competitive chlorination studies are discussed in relation to the uncertainly surrounding the Arrhenius parameters for the primary reference reaction, Cl + H2→ HCl + H.

Values for the kinetic isotope (H/D) rate constant ratios, (kCH4/kCD4) and (kCHCl3/kCDCl3), were measured over wide ranges of temperature: log10(kCH4/kCD4)=(–0.155 ± 0.024)+(384 ± 12) K/T, 298–1018 K; log10(kCHCl3/kCDCl3)=(–0.014 ± 0.020)+(167 + 9) K/T, 298–1006 K. These results are in agreement with the predictions of the semi-empirical BEBO (bond-energy-bond order) method.

Back to tab navigation
Please wait while Download options loads

Article type: Paper
DOI: 10.1039/F19736901547
Citation: J. Chem. Soc., Faraday Trans. 1, 1973,69, 1547-1567
  •   Request permissions

    Absolute rate constants for elementary reactions in the chlorination of CH4, CD4, CH3Cl, CH2Cl2, CHCl3, CDCl3 and CBrCl3

    M. A. A. Clyne and R. F. Walker, J. Chem. Soc., Faraday Trans. 1, 1973, 69, 1547
    DOI: 10.1039/F19736901547

Search articles by author