Cobalt-60 radiation-initiated oxidation of hydrocarbons in emulsion

Abstract

Aqueous emulsions of a variety of hydrocarbons under cobalt-60 irradiation have been allowed to react with molecular oxygen at pressures of 1-4 atm at 50°. Unlike the effect observed in polymerization, emulsification of styrene had no significant effect on the oxidation rate or products as compared to that observed in hydrocarbon solution. With emulsions of styrene and -methylstyrene, dependency on the rate of initiation and temperature is consistent with the bulk mechanism, and the product distribution qualitatively parallels bulk oxidations. Other hydrocarbons investigated include cyclohexene, cyclopentene, tetramethylethylene, tetralin, and cumene.

Effect of Viscosity on the Autoxidation of Emulsions

“…by using our earlier observation that the rate depended on the one-half power of the emulsifier concentration. 3 In the styrene and Tetralin experiments, 5.55 ± 0.05 g/1. was used for the standard emulsifer concentration.…”

“…Emulsifiers were from the same source as previously described. 3 Most of the techniques employed were as previously described.3 The polymer latexes were synthesized by emulsifying the appropriate monomer, then exposing the emulsion to Co-60 radiation at a rate of 200 rads/min. The progress of the polymerization was followed by removing samples, breaking the emulsion with methanol, and analyzing for unreacted monomer in the supernatant by GLC.…”

“…Most recently we have surveyed the oxidation of various emulsified hydrocarbons by molecular oxygen using a number of different emulsifying agents at controlled rates of initiation and have failed to find evidence that a simple emulsification has any effect on rate or products. 3 Because viscosity of the media is important in polymerization and appears to contribute to rate enhancement, at least in the final stage of an emulsion polymerization,4 we have sought to determine whether there is an effect of viscosity in autoxidation. Since chain-carrying species in autoxidation have a low molecular weight compared to those in polymerization, one might expect much less dependence on viscosity.…”