Mercury Photosensitized Oxidations in the Gas Phase

Abstract

This thesis describes experiments on the mercury-photosensitized oxidations of some hydrocarbon alkenes with molecular oxygen. Products have been identified and variations in product yields studied in detail as a function of alkene/oxygen ratio, total pressure, incident light intensity and time for 2-methyl propene. The reactions of propene and butene-1 have also been studied but in rather less detail. To assist the interpretation of the results the reactions of the alkenes were also studied with (a) ground state oxygen atoms generated by mercury-sensitized decomposition of nitrous oxide, and (b) electronically excited oxygen molecules (102*) formed in a microwave discharge through oxygen at low pressures. Comparison of the results showed that the presence of neither singlet oxygen molecules nor oxygen atoms alone was sufficient to account for the observed products of the mercury-sensitized oxidations. In fact, it was necessary to include ozone as a reaction intermediate forming some of the observed products. Plausible routes for the formation of the main reaction products and some minor reaction products have been suggested, and shown to be reasonably consistent with the observed variations in product yields with the reaction parameters. Because of the complexity of the reaction system, it was not possible to attempt to account quantitatively for the observed yields of the products