Man, John Tin Wing; (1993) Activation of peroxidic oxygen. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Hydroperoxides are convenient rather mild oxidising agents. The aim of this work was to examine new ways of enhancing their oxidising power to provide the basis for a new peroxide-based oxidation system for application in industrial processes and an approach to a new low-temperature household bleaching system. The reactivity of alkyl hydroperoxides has been previously shown to be enhanced by geminal alkylation to give dialkyl peroxonium ions. This work examines the reaction of the cyclic bromohydroperoxides 5-bromocycloocten-l-yl hydroperoxide, 6-bromocycloocten-1-yl hydroperoxide and 5-bromocyclohepten-l-yl hydroperoxide with silver trifluoroacetate to form dialkyl peroxonium ions. These hydroperoxides were readily prepared from their parent alkenes by singlet oxygenation. Formation of the expected bicyclic ethers from these hydroperoxides with concomitant oxidation of phenyl methyl sulphoxide provides evidence for the intermediacy of the dialkyl peroxonium ion in these cases. The synthesis of ortho halomethyl benzyl hydroperoxides by homolytic and heterolytic methods was examined the aim here was the preparation of an ortho halomethyl substituted cumene hydroperoxide. This work led to a synthesis of the hydroperoxide 2-bromomethyl alpha methoxy benzyl hydroperoxide by ozonlysis. The reaction of this hydroperoxide with silver salts was examined. We presumed that the principles relied upon to activate hydroperoxides could be further extended to the activation of a peroxyacid by preparation of precursors capable of forming an acyl alkyl peroxonium ion and ortho halomethyl substituted benzoic acids and their related peresters were prepared. The results of this study suggest that intramolecular ring closure to form an acyl alkyl peroxonium ion is a disfavoured process compared to intermolecular substitution in this type of system.

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