[en] It is believed that this is the first time the subject as such has been reported on in this series: therefore a general account of the theory and practice of the technique is given, with key references. The plan of the article is to summarize first the terms used, and the theoretical treatment. This is followed by a section on experimental methods and on the interpretations of the experimental results. Finally, an account is given of applications of the method in the cases of carbon, nitrogen, oxygen, sulphur and chlorine. (U.K.)

[en] Chlorine kinetic isotope effects have been investigated for the pyrolysis of 1-chloroethane in a static system in the temperature range 395 to 482⁰C. The temperature dependence of the kinetic isotope effects has been determined. The mass spectrometric isotope ratio analysis was made on the hydrogen chloride produced. A model for the chlorine involvement in the four-centre activated complex is advanced and various alternative geometries are evaluated in terms of heavy-atom approximation and first-order high temperature kinetic isotope effects. Best agreement with the experimentally determined values of k³⁵/k³⁷ is given by a model of the activated complex which involves chlorine participation in the reaction coordinate with three degrees of freedom. The effect of the individual geometric parameters that includes the C-Cl stretching, the C-C-Cl bending and the C-CH₃ stretching and their combination, is evaluated. (author)

No abstract available

No abstract available

[en] A study of ³⁵k/³⁷k for the gas-phase elimination of hydrogen chloride from ethyl chloride is reported. The value found at 723K is 1.001 5+-0.000 2. Heavy atom kinetic isotope theory is applied in an attempt to characterise the transition state. It is concluded that there is only a moderate lengthening of the carbon-chlorine bond, and only a little motion of the chlorine atom in the transition state. (author)