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Title: Polymethylene pyridines
Author: Brittain, David Robert
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1965
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This thesis describes a series of attempts to synthesise 2,5- and 1,4-polymethylene bridged pyridines. Nuclear magnetic resonance theory predicts that protons, which are held directly over an aromatic ring, will be abnormally shielded compared with protons in aliphatic straight-chain hydrocarbons. This prediction has been verified for the central methylene protons of paracyclophanes. The degree of shielding, expressed in terms of the distance from the aromatic ring, is a measure of the induced ring current and hence the aromaticity of the benzene ring. Similar measurements upon 2,5- or 1,4— polymethylene bridged pyridines would make it possible to determine the degree of aromaticity of the pyridine ring relative to benzene. A review of the subject of aromaticity is presented in which special reference has been made to its interpretation by nuclear magnetic resonance. The synthetic work has not been brougL.t to a truly satisfactory conclusion. However, the synthetic routes to 2,5-dialkylpyridines have been thoroughly investigated and a wide variety of such compounds prepared. The functional groups at the ends of the alkyl chains have been varied in an effort to produce a derivative which would cyclise to give a 2,5-bridged pyridine. The attempted intramolecular oxidative coupling of 2,5-dihex51 -ynylpyridine received much attention. In the attempts to obtain a 1,4-bridged pyridine, two tricyclic compounds, each containing two quaternised pyridine rings linked by polymethylene chains, were obtained. As a result of these investigations, several alternative routes to bridged pyridines are suggested.
Supervisor: Elvidge, J. A. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available