This thesis encompasses the successful synthesis, characterization (NMR, IR, TGA) and electrochemical testing of novel, potentially redox-active organic materials. These were destined as electrodes for Li-organic cells and/or as catalysts for Li–O2 cells. The electrochemical performance of the dilithiated and tetralithiated salts of 2,5-dialkylamide hydroquinones (with ethyl, isopropyl or benzyl as the alkyl group) and of a partially lithiated polymer with a backbone of alternating 2,5-dicarbonylhydroquinone and 1,4-benzyl diaminophenylene units was evaluated. The small organicsalts exhibited redox-activity around 1.0 V vs Li/Li+ (the terephthaloyl redox system) and 2.8 V vs Li/Li+ (the quinone redox system). These values drifted depending on lithiation degree and alkyl substituent. Redox irreversibility featured these materials which decomposed and dissolved. The polymer exhibited multiple redox-activity in the region of 2.5-3.6 V vs Li/Li+, which was however also irreversible. Further on, the small organic salts were tested as to their impact on the dischargeproduct (Li2O2) yield in Li-O2 cells. Discharge profiles of cells with and without the inclusion of the salts were contrasted to each other; the former having a jagged appearance, indicative of side-reactions. The O2 electrode was studied by XRD todetect the formed products and the amount of Li2O2 present was quantified throug htitration and UV-vis spectroscopy. Organic salt inclusion was found to negatively affect the Li2O2 formation and also attack the Li-electrode.

The goal of this research was to develop alternate economic routes for the synthesis of functionalised triarylphosphines. Such species are employed as catalysts ligands in chemical synthesis and can be incorporated into designed-ylides for olefination reactions. The synthesis of the SHOP ligand, the key constituent of the Shell Higher Olefins Process for making linear alpha olefins via ethylene oligomerisation and olefin metathesis, is described using four totally new approaches. These include a Directed Ortho Metalation (DOM) approach, Copper iodide catalyzed cross-coupling, Halogen-Magnesium Exchange reaction and Diazonium salt approaches. The efficiency, in terms of overall yield and mild process conditions, make some of the routes potentially commercialisable. Additionally, a series of ortho-substitued triarylphosphines were derived to probe and modulate the reactivity of the Wittig reaction. We report that non-stabilized ortho-P-alkoxy-substituted ylides react with aromatic and aliphatic aldehydes providing (E)-olefins with high stereocontrol employing an intramolecular phenoxy and alkoxy substituent to promote (E)-olefination through betaine interconversion. In one particular case; removal of phosphoine oxide was also achieved. Extension of this methodology was also carried out on semi-stabilized benzylic ylides, which are known for producing 1:1 mixtures of (E):(Z) olefins under classical condition. Potential applications of the methodology are also described. / Thesis / Master of Science (MSc)

Aliphatic polyesters such as polycaprolactone and polylactide have received more attention in recent years for their use in biomedical applications because of their biodegradable nature. These polymers are often synthesized using homogeneous metal complexes. Unfortunately, using homogeneous metals as catalysts leads to metal contamination in the product polymer, a result which is highly undesirable in a polymer intended for biomedical use. More recent work has shown that these polymers can be synthesized using homogeneous metal-free complexes. These catatlysts are generally less active than metal catalysts, and although they do not contaminate the polymer with metal residue, they are still difficult to recover and hence recycle for further use. In this work, we attempted to create a metal-free, silica-supported catalyst for use in the synthesis of polycaprolactone or polylactide. Ultimately, n-propylsulfonic acid-functionalized porous and nonporous silica materials are evaluated in the ring-opening polymerization of epsilon-caprolactone. All catalysts allow for the controlled polymerization of the monomer, producing polymers with controlled molecular weights and narrow polydispersities. Polymerization rates are low, with site-time-yields generally one to three orders of magnitude lower than metal-based systems. The catalysts are easily recovered from the polymerization solution after use and are shown to contain significant residual adsorbed polymer. Solvent extraction techniques are useful for removing most of the polymer, although the extracted solids are not effective catalysts in recycle experiments. These new materials represent a green alternative to traditional metal-based catalysts, as they are recoverable and leave no metal residues in the polymer.

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