Polyisobutylene as a Polymer Support for Homogeneous Catalysis

Abstract

Phase selective soluble polymers are useful in organic synthesis because they simplify purification and separation processes. Such selective soluble polymers enable the use of Green chemistry principles to be utilized as ways to simplify catalyst, reagent, and product recovery. Polyisobutylene oligomers serve as examples of such polymers. Vinyl terminated polyisobutylene (PIB) oligomers can be easily transformed into a variety of end-functionalized PIB oligomers. Previous work has shown that PIB oligomers possess nonpolar phase selective solubility that allows them to be used as polymer supports for ligands and catalysts in liquid/liquid biphasic systems. This dissertation focuses on the use of PIB oligomers as supports for a salen Cr(III) complex, a Hoveyda-Grubbs 2nd generation catalyst, and a N-heterocyclic carbene. The syntheses of these PIB-supported ligands and catalysts are simple and straightforward. The synthetic products and the intermediates in these syntheses can all be readily analyzed and monitored by conventional spectroscopic methods. The activity of the PIBsupported catalysts is shown to be analogous to that of other soluble polymer supported catalysts or their non-supported analogs. The PIB-bound catalysts can be separated from products by a latent biphasic, liquid/liquid extractions, or product self-separation systems. The recovered PIB-bound catalysts can then be recycled multiple times.