The thermal decompositions of ethylene oxide, propylene oxide, dimethyl ether and dioxane in a stream of helium have been studied by means of a mass spectrometer designed to permit the measurement of free radical concentrations. With ethylene oxide it was found that each molecule decomposing gave rise to about 0.6 methyl radicals, and in propylene oxide the corresponding number had a lower limit of 0.36. Methyl radicals were also abundant in the decomposition of dimethyl ether. In the decomposition of dioxane only a small number of methyl radicals were found, and they probably come from a secondary reaction. No other radicals were detected, although formaldehyde was found to be a comparatively long-lived intermediate in the decomposition of dimethyl ether. The effect of the addition of nitric oxide on the decomposition of ethylene oxide was examined. Average values for the collision efficiency of the nitric oxide+methyl radical reaction at 950°, and the methyl radical recombination reaction from 925° to 975° were found to be 2 × 10-4 and 2.5 × 10-2 respectively.
Discussions of the Faraday Society14 (1953): 34–44.