Hammond, Max Leonard (2006) Imine catalyst stability. PhD thesis, University of Warwick.

Preview	PDF (Born digital final version) WRAP_THESIS_Hammond_2006_final.pdf - Submitted Version - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader Download (6Mb)
	PDF (EThOS Scanned File) WRAP_THESIS_Hammond_2006.pdf - Draft Version Restricted to Repository staff only - Requires a PDF viewer such as GSview, Xpdf or Adobe Acrobat Reader Download (10Mb)

Abstract

Chapter 1 presents a review of the background and current research regarding Schiff-base olefin polymerization catalysts, with special reference to the salicylaldimine species. An attempt is made to review trends within the current literature. Chapter 2 describes the synthesis and polymerization properties of tetradentate ligands with a bibenzyl backbone at titanium and zirconium centres, prepared with the intent of sterically hindering a 1,2-Migratory Insertion into the ligand imine functionality. A custom-built polymerization reactor was used to determine the stability of the catalytic systems. Steric protection is moderately successful in enhancing the stability of these systems. Chapter 3 reports the synthesis and detailed polymerization behaviour of a series of group 4 catalysts based on salicyloxazoline ligands, which should be resistant to 1,2-Migratory Insertion. Comparisons are made between polymerization under different conditions, including using High-Throughput methodology to screen catalysts under a range of differing conditions rapidly. Such systems are extremely active for polymerization of ethene, but demonstrate limited stability at elevated temperature. Chapter 4 presents our investigations into the polymerization behaviour of salicyloxazoline catalysts containing a para-methoxy substituent on the phenoxy donor unit. This substituent significantly enhances the stability of the catalysts at elevated temperature. Chapter 5 explores the nature of the active species in polymerizations with group 4 salicyloxazoline species. Alkyl cations of such species are generated from metal alkyl species with borate activators, and also from metal chloride species with MAO. We conclude that the primary deactivation mechanism is loss of ligand to aluminium co-catalyst, and that the methoxy substituent prevents this. A computational approach (DFT) is also applied, to examine the catalytic pathways which may be available to various stereoisomers of the catalyst. Chapter 6 details the experimental procedures used during this work.

Item Type:	Thesis or Dissertation (PhD)
Subjects:	Q Science > QD Chemistry
Library of Congress Subject Headings (LCSH):	Imines, Catalysts, Alkenes, Polymerization
Date:	May 2006
Institution:	University of Warwick
Theses Department:	Department of Chemistry
Thesis Type:	PhD
Publication Status:	Unpublished
Supervisor(s)/Advisor:	Scott, Peter, 1965 Dec. 10-
Format of File:	pdf
Extent:	201 leaves : ill., charts
Language:	eng
URI:	http://wrap.warwick.ac.uk/id/eprint/1172

Request changes to a record

Actions (login required)

View Item