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Title: Transformations of cyclic phosphorus imines
Author: Taylor, Malcolm A.
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1979
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The concepts of "pseudorotation" and "turnstile rotation" in phosphorane species are discussed in the light of the literature evidence available. This leads to the concepts of "apicophilicity" and "apicophobia" of various ligands in such species. Results of various kinetic experiments are then discussed in view of these concepts and the theory that ring strain plays a major part in the rates of reactions involving phosphoranes as intermediates or transition species is developed with emphasis on the accelerations noted in rate when smaller rings are present. This theory is then postulated as explanation of the observed decompositions of various phospholimines by Cadogan and Scott and the zero reaction of various acyclic phosphinimines. To test this theory a variety of cyclic and acyclic phosphinimines were synthesised and allowed to decompose at 160° in bromobenzene while the reaction was followed by 1B N.m.r. spectroscopy. Various rates of reaction were observed dependent on ring size and the apicophilicity of the atoms bonded to phosphorus. A notable result was the very slow rate of reaction, comparatively, when the phosphorus was constrained in a dioxaphospholan type ring. This result led to observations of the reaction by 31P N.m.r. and an intermediate species was noted in this reaction. No such intermediate was noted when the phosphorus was constrained in a phosphole or phospholan type ring. A further major result was the observation of the formation of 4-substituted-3-nitroanilines in these reactions which was shown to occur even during vacuum thermolysis so excluding hydrolysis as the cause. These observations led to a revision of the reaction mechanism as proposed by Cadogan and Scott.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available