AbstractMeasurements rate constants for abstraction of hydrogen from ethylene by methyl and ethyl radicals relative to the corresponding rate constants for abstraction from hydrogen, over the temperature range 650–770 K, are reported. The methodis based on the effect of the addition of small quantities of hydrogen on the rates of formation of methane and ethane in the thermalchain reactions of ethylene. On the assumption that methane and ethane are formed by the following reactions:measurements of the relative rates of formation of methane and ethane in the presence and absence of hydrogen gave the following ratios of rate constants: (R= 8.314 Joule mol−1K−1)\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} {\rm log(}k_1 /k_2) = 1.3 \pm 0.15 + 4000 \pm 2000/2.3RT \\ {\rm log(}k_3 /k_4) = 1.6 \pm 0.15 - 0 \pm 2000/2.3RT \end{array}$$\end{document}With values from the literature for