Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.776779
Title: The preparation and nuclear magnetic resonance spectra of some volatile fluorine compounds
Author: Winfield, John M.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1964
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Abstract:
The preparation of alkyl, phenyl and pentafluorophenyl derivatives of non-metallic fluorides has been attempted by reaction of a fluoride with a tetraorganotin. A smooth reaction occurred only with fluorides that are strong Lewis acids. In other cases decomposition of the organotin molecule occurred under the conditions necessary to initiate the reaction. The reactions are discussed in relation to the chemistry of organotin compounds and the Lewis acidic or basic character of the fluorides. The reactions of bis(trifluoromethyl)peroxide with some metal carbonyls have been carried out with a view to preparing trifluoromethoxy derivatives of metal carbonyls. In most cases bis(trifluoromethyl)peroxide reacted as a fluorinating agent; where other products were formed, they were very unstable. The nuclear magnetic resonance spectra of some polychloropolyfluorobenzenes and fluorobenzenes containing methyl, carboxylic ester and nitro substituents are described, 19F-19P and 1H-19P spin-spin coupling constants in these compounds are characteristic of the ring positions that the atoms occupy. This has enabled the structures of the compounds to be determined where they were unknown. The effect on the 19F chemical shift of chlorine and fluorine atoms in different ring positions has been determined and empirical relationships found for the change in the 19F chemical shift with a chlorine for fluorine substitution in the ortho, meta and para ring positions. Using these relationships the structures of some chlorofluorophenols have been determined. The effect that a ring substituent in a given position has on the 19F chemical shift is modified by adjacent substituents. This has been shown also for methyl, carboxylic ester and nitro substituents. Both steric and electronic factors determine a substituent's effect on the 19F chemical shifts. The 19F nuclear magnetic resonance spectra of the three isomers of the 4-dichlorotetrafluorobutadiene, the two isomers of 4-dichlorotetrafluorocyclobutene-l and of two chloropolyfluorocarbon derivatives of sulphur hexafluoride are described. The chemical shifts and coupling constants found are discussed in relation to current theories. The coupling constants of the 1,4-dicalorotetrafluorobutadiene isomers have permitted some observations on their conformations to be made Coloured solutions of tungsten hexafluoride in several organic donor solvents and of molybdenum hexafluoride and tantalum pentafluoride in hexafluorobenzene have been prepared. The 19F nuclear magnetic resonance spectra of the molybdenum and tungsten hexafluoride solutions show the presence of hesnfluoride molecules, inferring that the colours are due to charge transfer interaction. However the effect of such interaction upon the 19F chemical shift of the hexafluoride is small. Evidence for the presence of lower valency states of tungsten was found in diethyl ether solutions.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.776779  DOI: Not available
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