Non-polar phase selectively soluble polyisobutylene (PIB) is a useful polymer as a polymer support for homogeneous catalysts. Substitution of PIB onto other useful ligands alters the solubility properties of original ligands. However, such chemical modification of PIB polymers is challenging due to its limited synthetic availability. This dissertation describes the end functionalization of this terminal alkene functionalized PIB into variety of other functional groups via variety of chemistries such as electrophilic aromatic substitutions, nucleophilic aromatic substitution reactions and alkylation reactions. PIB-anilines and PIB-phenols can be prepared via electrophilic aromatic substitution reactions of anilines and phenols by PIB-alkene. Excellent oxidative and chemical resistance and nonpolar phase selective solubility of these modified PIB polymers allow these materials to be useful as soluble polymer supports for ligands and transition metal catalysts. This dissertation details immobilization of palladium and ruthenium catalysts on to these modified PIB ligands and their catalytic properties and catalyst recyclability. PIB-bound palladium catalyst was used as a recyclable homogeneous catalyst for cross coupling reactions in a thermomorphic liquid/liquid separation system- biphasic at a lower temperature and monophasic at a higher temperature. Application of a ‘solid solvent’-(Polywax) in place of a organic solvent is also described and improved metal sequestration of this liquid/solid catalyst/product separation compared to the thermomorphic liquid/liquid separation strategy is also investigated. A PIB-bound ruthenium visible light photo-redox catalyst was prepared and its catalytic activity and recyclability in free radical polymerization reactions of acrylates is also reported. At the end this dissertation details the extension of PIB’s utility as a nonpolar phase anchor to functionalize polyolefins with dyes. This is illustrated by preparing PIB-bound metallophthalocyanine dyes in a series of reactions starting with 4-nitro phthalonitrile. The non-polar solvent solubility of these dyes allowed their use in dyeing commercial polyethylene and polypropylene.

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Polymer-supported reagents and catalysts have been extensively studied in the past few decades as they not only facilitate separation and isolation of products after reactions but also enable reuse of reagents/catalysts. In particular, chemistry using polymer-supported organocatalysts has the advantage of avoiding the use of sometimes toxic transition metals. Since organocatalysts are often used at high mol% loading in catalytic reactions, immobilizing organocatalysts on polymers for recycling and reusing makes chemistry using organocatalysts attractive in larger scale syntheses. Chapter II of this dissertation focuses on using variable temperature 31P NMR spectroscopy to study and compare the dynamic behavior of silver complexes prepared from soluble polymer-supported phosphines and electronically similar low molecular weight phosphine ligands. The phosphine-silver complexes supported on terminally functionalized polyisobutylene (PIB) and poly(ethylene glycol) show similar kinetic behavior compared to their low molecular weight counterparts. However, the dynamic behavior of phosphine-silver complexes supported as pendent groups on a linear polystyrene is difficult to study because of significant line-broadening on 31P NMR spectra. Chapter III of this dissertation aims at examining the recyclability and reusability of PIB-supported phosphines as organocatalysts and reagents. PIB-supported alkyldiphenyl- and aryldiphenylphosphines were prepared and used as recyclable organocatalysts in addition and allylic amination reactions. The PIB-bound phosphines were useful reagents in aza-Wittig and Mitsunobu reactions. The PIB-bound phosphine oxides formed either from adventitious oxidation or during the course of reactions can be reduce to PIB-phosphines for reuse. Chapter IV of this dissertation describes preliminary studies on soluble polymer-supported N-heterocyclic carbene (NHC) organocatalysts. PIB- and polyethylene oligomer (PE_Olig)-supported NHC adducts were synthesized and the corresponding polymer-supported NHC catalysts were generated in situ in lactide polymerization and phenyl isocyanate trimerization reactions. The PIB-bound NHC catalyst generated in situ was not recyclable in a lactide polymerization. However, PIB- and PEOlig-bound NHC precatalysts showed modest recyclability in lactide polymerization and phenyl isocyanate trimerizations.

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Soluble polymer supports facilitate the recovery and recycling of expensive transition metal complexes. Recently, polyisobutylene (PIB) oligomers have been found to be suitable polymer supports for the recovery of a variety of transition metal catalysts using liquid/liquid biphasic separations after a homogeneous reaction. Our work has shown that PIB-supported Ni(II) and Co(II) β-diketonates prepared from commercially available vinyl terminated PIB oligomers possess catalytic activity like that of their low molecular weight analogs in Mukaiyama epoxidation of olefins. Carboxylic acid terminated PIB derivatives can act as carboxylate ligands for Rh(II) cyclopropanation catalysts. An achiral PIB-supported Rh(II) carboxylate catalyst showed good activity in cyclopropanation of styrene in hydrocarbon solvents, and could be easily recycled nine times by a post reaction extraction. Further application of PIB supports in asymmetric cyclopropanation reactions were investigated using PIBsupported arenesulfonyl Rh(II) prolinates derived from L-proline as examples. The PIBsupported chiral Rh carboxylates demonstrated moderate activity and were recovered and reused for four to five cycles. The prolinate catalyst prepared from PIB-anisole also showed encouraging enantioselectivity and about 8% ee and 13% ee were observed on trans- and cis-cyclopropanation product respectively. Finally, PIB oligomers can be modified in a multi step sequence to prepare PIBsupported chiral bisoxazolines that can in turn be used to prepare active, recyclable PIBsupported Cu(I) bisoxazoline complexes for olefin cyclopropanation. These chiral copper catalysts showed moderate catalytic activity and good stereoselectivity in cyclopropanation of styrene. A chiral ligand prepared from D-phenylglycinol provided the most effective stereo control and gave the trans- and cis-cyclopropanation product in 94% ee and 68% ee respectively. All three PIB-supported chiral bisoxazoline-Cu(I) catalysts could be reused five to six times.

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