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Title: Studies of the radiation-induced oxidation of organic compounds
Author: Francis, John Michael
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 1963
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This thesis describes a detailed investigation of the radiation-induced oxidation of ethylene in aqueous solution at ambient temperatures and under gas pressures of from 5 to 40 atmospheres. In Section I, previous work on the radiation-induced oxidation of organic compounds is discussed alongside the results of autoxidation studies carried out with the corresponding classes of compounds. Comparison of the two types of reaction shows several points of interest attaching to the oxidation of olefins. Section II describes the apparatus constructed for the preparation and handling of solutions of ethylene-oxygen mixtures at high pressures. An account is also given of the procedure used in carrying out the radiolysis, and of the specially sensitive methods for the identification and estimation of the products formed, many of which are only present in very low concentration. The results presented in Section III relate to the gamma-radiolysis of ethylene and ethylene-oxygen solutions, and the influence on the products of dose, reactant gas pressures, pH of the solution and additives has been systematically investigated. In the absence of oxygen, polymerisation (to yield what is essentially polyethylene ) is the main process, although smaller amounts of hydrogen peroxide and of C2 - C4 aldehydes are formed simultaneously. The rate constant for the reaction of the solvated electron with ethylene has been determined directly by a pulse radiolysis technique. In the presence of oxygen, polymerisation is inhibited and quite a variety of oxygenated organic products are formed; these include formaldehyde, acetaldehyde, and propionaldehyde. An important stage in the reaction appears to be the formation of theft-hydroxyethylhydroperoxy radical, some evidence for which has been obtained during pulse radiolysis experiments. In addition, the organic peroxide, which is formed in the irradiated solutions simultaneously with hydrogen peroxide, has been tentatively identified beta-hydroxyethylhydroperoxide. Finally, in Section IV, the probable reaction paths of the various radical and ionic species formed during the radiolysis are discussed in relation to the experimental measurements recorded in the previous Section. The initial reaction in both the oxygen-free and oxygen-containing systems appears to involve addition of the primary species formed from water to the solute ethylene molecules. Reaction schemes involving secondary reactions of the initial species so formed are suggested to account for the formation of the oxidation products observed.
Supervisor: Cullis, C.F.; Swallow, A.J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available