Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.704215
Title: The thermal decomposition of diaroyl peroxides in some solvents
Author: Coleman, Michael William
Awarding Body: University of London
Current Institution: Royal Holloway, University of London
Date of Award: 1972
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Abstract:
The mechanism of the thermal decomposition of perfluorobenzoyl peroxide in benzene has been investigated in a study of the reaction kinetics and product distributions for a series of initial peroxide concentrations. The initial thermal dissociation of the peroxide is superimposed on a 1.5-order induced decomposition at low and on a first-order induceddecomposition at higher [P]o. The pentafluorobenzoyloxy radicals which are formed from the initial homolysis either attack the solvent or decarboxylate to pentafluorophenyl radicals which also attack the solvent, both processes forming a-complexes. These a-complexes are responsible for induced decomposition in chain propagation reactions. At low [P] chain termination occurs through dimerisation ofsimilar a-complexes; at higher CPQ chain termination occurs by reaction of pentafluorobenzoyloxy radicals with a-complexes. The thermal decomposition of perfluorobenzoyl peroxide in chlorobenzene and broraobenzene was investigated. Stabilisation of pentafluorobenzoyloxy radicals in these solvents produces high stationary concentrations of the corresponding a-complexes. The first-order thermal dissociation of the peroxide is superimposed on a first-order induced decomposition over the whole [P] range in both solvents.e-complexes are responsible for the induced decomposition, and chain termination occurs primarily through halogen abstraction from a-complexes by pentafluorobenzoyloxy radicals. The perfluorobenzoyl peroxide-fluorobenzene reaction has also been studied. Investigation of the benzoyl peroxide-hexafluorobenzene reaction shows the initial first-order homolysis occurring concurrently with a 1.5-order induced decomposition. Phenylation of hexafluorobenzene forms a-complexes which are responsible for the slow induced decomposition. Chain termination occurs mainly by dimerisation of a-complexes producing a high-boiling residue. Thermal decomposition of diaroyl peroxides in several perfluoroalicyclic solvents was studied with the aim of finding a group of solvents which are insert to free-radical attack. Reaction products were found to be derived solely from the peroxides so that radical interaction with the solvents appears unlikely.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.704215  DOI: Not available
Keywords: Chemical Engineering
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