The development of cationic zinc complexes as a new class of lactide polymerization catalyst
Wheaton, Craig Andrew
Lethbridge, Alta. : University of Lethbridge, Dept. of Chemistry and Biochemistry, 2011
The thesis outlines the development of novel cationic zinc complexes for application in lactide polymerization catalysis. These complexes were characterized spectroscopically and crystallographically, and where appropriate their efficacy as catalysts for the polymerization of lactide was evaluated. The strongly donating, neutral chelating ligands employed in this study were prepared by installation of either one or two phosphinimine donors on a dibenzofuran backbone. An efficient synthetic methodology was then developed for the synthesis of cationic complexes of the formula [LZnE+][BAr4-], wherein E = C2H5, CH3, Ph, C6F5, OAc, OC6F5, or methyl-(D,L)-lactate, and AR = Ph, C6F5, or m-(CF3)2-C6H3. Only the cationic zinc-lactate species were found to be highly active polymerization catalysts. Tuning of the steric and electronic properties of the ligand resulted in the discovery of zinc-lactate systems that promote rapid and well-controlled polymerization of lactide under mild conditions, marking the first well-defined cationic metal catalysts to do so.
xxiv, 254 leaves : ill. ; 29 cm + 1 CD-ROM
Zinc compounds , Polymerization -- Research , Metal catalysts -- Research , Complex compounds , Coordination compounds , Dissertations, Academic