The luminous reduction of selenium dioxide

Abstract

In the course of some recent investigations on the oxidizing action of selenium dioxide on organic compounds it was found that, if the temperature was raised above the point required for the specific oxidizing reaction, the reduction of the dioxide was accompanied by a characteristic moonlight-like flame. This was first observed in the reaction of ethylene with selenium dioxide at a temperature of circa 400°C, but subsequently a number of other substances were found to behave similarly, the following having been studied in some detail: ethylene, acetylene, methyl-, ethyl-, and propyl-alcohols, acetaldehyde, acetone, benzene, toluene, ether, carbon disulphide, and ammonia. When the oxidation takes place at lower temperatures, i.e. , at temperatures which are not sufficiently high for the luminous reaction, intermediate products are formed from all of the carbon compounds. Acetaldehyde, for example, is oxidized quantitatively to glyoxal, the dioxide being reduced to elementary selenium, whilst ethylene also yields glyoxal. The present investigation was undertaken in the hope that the nature of the light emitted when the reactions are carried out at higher temperatures might possibly explain the highly selective nature of the oxidations at the lower temperatures.