I. Catalytic Conjugate Allylation of Alkylidene Malonates Nucleophilic conjugate addition of allylsilanes and allylstannanes to alkylidene malonates under the action of ytterbium catalysis in the presence of hexafluoro-isopropanol has been developed. Enantioselective conjugate allylation of alkylidene malonates under ytterbium or scandium catalysis using chiral bis(oxazoline) ligands allows access to the conjugate addition products in an enantiomerically-enriched form. Furthermore, elaboration of the allylated substrates via decarboxylation and an oxidative cleavage was demonstrated. II. Catalytic Enantioselective Conjugate Addition of Azaarylacetates and Acetamides to Nitroalkenes An enantioselective nickel-catalysed Michael addition of azaarylacetates and acetamides to nitroalkenes has been developed. A range of azaaryl pronucleophiles were shown to react with a variety of nitroalkenes to generate highly functionalised Michael addition products with impressive diastereo- and enantiocontrol. A possible mechanism for this process is proposed and crystal structures of the addition products have also been attained, allowing determination of the absolute stereochemistry. Elaboration and further functionalisation of these products was also possible under a range of conditions.

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This thesis concerns the preparation and use of diaryliodonium salts. In Project I various unsymmetrical diaryliodonium salts were reacted with three different nucleophiles in order to study the chemoselectivity of the reactions of the salts. The main focus of this project was to gain a deeper understanding of the underlying factors that affect the chemoselectivity in transition metal-free arylation reactions. They were found to be very nucleophile-dependent. Some nucleophiles were very sensitive to electronic effects, whereas others were sensitive to steric factors. Ultimately, some arenes are never transferred. A very interesting scrambling reaction was also observed under the reaction conditions, where unsymmetrical diaryliodonium salts form symmetrical salts in situ. Project II details the preparation of N-heteroaryliodonium salts via a one-pot procedure. The salts were designed so that the N-heteroaryl moiety was selectively transferred in applications both with and without transition metals. The chemoselectivity was demonstrated by selective transfer of the pyridyl group onto two different nucleophiles. The third project in the thesis discusses the synthesis of alkynyl(aryl)iodonium salts and alkynylbenziodoxolones from arylsilanes. This protocol could potentially be a very useful complement to the existing procedures, in which boronic acids are used. The last part of the thesis (Project IV) describes a C-2 selective arylation of indoles where diaryliodonium salts were used in combination with hetero-geneous palladium catalysis. This transformation was performed in water at ambient temperature to 50 °C, and tolerated variations of both the indole and the diaryliodonium salt. Importantly, several N-H indoles could be arylated. The MCF-supported Pd-catalyst showed very little leaching and it was demonstrated that the main part of the reaction occurred via heterogeneous catalysis. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Accepted.</p>

The importance of alkyl methacrylates has been firmly established within the chemical industry. For example, free radical polymers, which contain the methacrylate backbone are more rigid than acrylate polymers. Several methods have been reported for the production of alkyl methacrylates. The aim of this project is focused on isolating a phase specific iron phosphate catalyst and thereafter testing its efficacy in oxidative reactions to form ethyl methacrylate in a one step process in the gas phase using a fixed bed continuous flow reactor. The catalyst was characterized by using Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), Brunauer-Emmett-Teller (BET) surface area measurements, Attenuated Total Reflection-Infrared (ATR-IR) Spectroscopy, Scanning Electron Microscopy (SEM), Temperature Programmed Reduction (TPR), Temperature Programmed Oxidation (TPO), Energy Dispersive X-ray (EDX) determination, Temperature Programmed Desorption (TPD), Room Temperature X-ray Diffraction (XRD), In situ X-ray Diffraction (In situ XRD), Thermogravimetric/Differential Thermal Analysis (TGA/DTA), Transmission Electron Microscopy (TEM), Mössbauer Spectroscopy and Raman Spectroscopy. A further venture included employing certain of the above techniques to characterize the cesium promoted iron phosphate catalyst as well as the spent catalysts. The catalytic activity of the iron phosphate based catalyst synthesized was investigated for the oxidative dehydrogenation (ODH) of ethyl isobutyrate (EIB) to ethyl methacrylate (EMA). Reaction conditions which were considered included variation in the contact time, co-feeding water at varying contact times, co-feeding ethanol at varying ratios, as well as co-feeding both ethanol and water and catalyst lifetime and regeneration studies. The cesium promoted iron phosphate catalyst was tested at optimal reaction conditions. The findings of the investigation showed that the tridymite-like FePO4 phase was the most suitable precursor to allow for the formation of the active α-phase during catalytic testing. It was found that the catalyst performed optimally at a contact time of 0.8 seconds and the beneficial effect of co-feeding water and ethanol primarily on conversion and selectivity towards EMA respectively, was demonstrated. Optimal results were obtained at a EIB:EtOH ratio of 1:5 with a conversion of 57 % and a yield of 34 mol %. The lifetime and regeneration studies showed that water had a significant effect on the regeneration of the catalyst after a specific time on stream and a shorter time on stream (i.e. 25 hours) prior to regeneration, minimized rapid deactivation of the catalyst. The characterization results obtained for the spent catalysts showed that under the reaction conditions considered with respect to co-feeds, the active α-phase and the Fe2P2O7 phase dominated. The cesium promoted iron phosphate catalyst was synthesized to favour stabilization of the tridymite-like structure. The results showed that a mixture of phases was observed for the synthesized promoted catalysts and there was an increase in EIB conversion as well as EMA selectivity with a decrease in cesium loading. However, the promoted catalyst with the lowest cesium loading (Cs/Fe = 0.10), showed a lower selectivity towards EMA relative to the unpromoted iron phosphate catalyst. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2012.

Nanomaterials have become a popular topic of research over the years because of their many important applications. It can be a challenge to stabilize the particles at a nanometer size, while having control over their surface features. Copper nanoparticles were synthesized photochemically using a photogenerated radical allowing spatial and temporal control over their formation. The synthesis was affected by the stabilizers used, which changed the size, dispersity, rate of formation, and oxidation rate. Copper nanoparticles suffer from their fast oxidation in air, so copper-silver bimetallic nanoparticles were synthesized in attempts to overcome the oxidation of copper nanoparticles. Bimetallic nanoparticles were synthesized, but preventing the oxidation of the copper nanoparticles proved difficult. One important application of nanoparticles that was explored here is in catalyzing organic reactions. Because of the fast oxidation of copper nanoparticles, silver nanoparticles were synthesized photochemically on different supports including TiO2 and hydrotalcite (HTC). Their catalytic efficiency was tested using alcohol oxidations. Different silver nanoparticle shapes (decahedra and plates) were compared with the spheres to see the different catalytic efficiencies.

Electrospray ionization mass spectrometry (ESI-MS) has been applied to the real time study of air-sensitive homogenous organometallic catalytic reactions due to its soft ionization properties. Therefore, fragile molecules and complexes in these reactions were characterized. The kinetic studies of these reactions have also been done by following the relative abundance of different species including starting material(s), products, by-product(s) as well as intermediates. Based on the results, reaction pathways and mechanisms were proposed and numerical models were built to accurately mimic the reactions under specific condition. In order to make the reactions detectable by ESI-MS, many charged ESI-MS friendly substrates were synthesized as tracking tags, including 1-allyl-1-(prop-2-yn-1-yl)piperidin-1-ium hexafluorophosphate(V), 1-allyl-1-(prop-2-yn-1-yl)pyrrolidin-1-ium hexafluorophosphate(V), (4-ethynylbenzyl)triphenylphosphonium hexafluorophosphate(V), hex-5-yn-1-yltriphenylphosphonium hexafluorophosphate(V) etc. The method for continuously monitoring water- and oxygen-sensitive reactions in real time named pressurized sample infusion (PSI) was developed, optimized and applied throughout all the projects in the thesis. These techniques were applied to detailed studies of the intramolecular Pauson-Khand reaction (PKR) with Co2CO8 under different temperatures. The kinetic study results gave the entropy and enthalpy of the reaction and evidence suggested that the ligand dissociation step was the rate-determining step of the reaction. Hydrogenation of alkynes with Wilkinson’s catalyst and Weller’s catalyst were also studied using PSI. The behaviour of starting materials and products were tracked, then various reactions were carried out by using different temperatures and concentrations. Furthermore, competition reaction and kinetic isotope effect study, mechanisms were proposed based on experimental results, numerical models were built, and rate constants for each step were estimated. Different Si-H activation reactions were studied including hydrolysis of silanes, hydrosilation, dehydrocoupling of silanes, alcoholysis of silane and silane redistribution by using (3-(methylsilyl)propyl)triphenylphosphonium hexafluorophosphate(V). A variety of collaborative projects were also carried out including hydroacylation, fast-activating Pd catalyst precursor, catalyst analysis for Cu-mediated fluorination, CdSe - NiDHLA analysis, Ru catalyzed propargylic amination reaction, Zn catalyzed lactide polymerization, and Fe4S4 clusters. / Graduate / jingwei@uvic.ca

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Reaction of unsymmetrical allylic electrophiles with amines gives rise to regioisomeric allylamines. It was found that linear products result from the thermodynamically controlled isomerization of the corresponding branched products, which form initially. The isomerization was found to be promoted by the presence of acid and active palladium catalyst. The use of base shut down the isomerization pathway and allowed for the preparation and isolation of branched allylamines. This methodology provides a powerful control element, which allows for the installation of quaternary and chiral centres next to nitrogen. Later, the isomerization was combined with ring-closing metathesis to afford the synthesis of exocyclic allylamines from their thermodynamically less-stable endocyclic precursors. This rearrangement became feasible as a result of the electrophilic nature of a C – N bond in allylamines. When compared to the conventional intramolecular allylic amination, such approach escapes chemoselectivity issues, which makes it attractive attractive for late-stage synthetic modifications.

The wettability of materials is important in many natural and industrial processes. In this thesis, the wettability of chemically heterogeneous surfaces was investigated with respect to the size, shape and orientation of individual defects. Heterogeneous surfaces were structured by photolithography, using self-assembled monolayers (SAMs) of diverse functionality and, thus, wettability. In order to maximise any possible departure from theory, the wettability of the high-and low-energy regions of these heterogenous surfaces was chosen to differ substantially. The purity of the defects was optimized by studying the SAM formation and the patterning processes, whilst the influence of roughness was minimized. The focus of this work is therefore on chemical heterogeneity. The Wilhelmy plate method was employed to ascertain the wetting behaviour of individual high- and low-energy defects. Simultaneous measurement of the capillary force and the plate position allowed full characterization of the wettability at the defect boundaries. In addition, integration of the Wilhelmy trace enabled the work associated with advancing or receding a liquid over these defects to be quantified. / The defect boundary orientation was of critical importance to the wetting behaviour. Wetting boundaries perpendicular to the liquid front did not result in any deviation from theoretical predictions. Wetting boundaries that were arranged parallel to the liquid front, however, caused contact line pinning which, in turn, caused contact angle hysteresis. Therefore these boundaries are directly responsible for the departure from wetting theory for heterogeneous surfaces (i.e. the Cassie Equation). These observations are consistent with earlier studies of wetting hysteresis by Johnson and Dettre (1964) and Neumann and Good (1972). Extending their work, this thesis examined the extent of wetting hysteresis at individual rectangular defects with respect to the defect dimensions. The nature of wetting hysteresis was studied quantitatively and, as a result, a simple model for hysteresis was proposed. This model predicts that, for a high-energy defect, the work associated with an advancing liquid will always be less than the theoretical value due to capillary rise within the effect. However, the work associated with a receding liquid will be equal to the theoretical prediction (the opposite is true for low-energy defects). The proposed model was validated for two different liquids (water and ethylene glycol) rectangular and circular defects of macroscopic dimensions. For these surfaces, the empirical data and the proposed model showed excellent agreement for both high- and low-energy defects. This agreement is strong evidence that high- and low-energy defects induce distinctly different wetting behaviour on heterogeneous surfaces. / The proposed model for hysteresis was qualitatively applied to heterogeneous surfaces containing micro- and nanoscopic defects. For micropatterns of high- and low-energy defects, of identical composition, the wettability was entirely different. High-energy defects induced a deviation from theory for only the advancing contact angles, whilst low-energy defects only influenced the receding angles. These observations were qualitatively consistent with the outcomes predicted by the proposed model for hysteresis. For nanoscopic defects, however, the advancing contact angles were consistent with Cassie's law within reasonable error. The derivation of Cassie's equation assumes that there is no capillary rise within the chemical defects. The capillary rise within a nanoscopic defect must be extremely small, according to extrapolation of measurements performed on macro and microscopic defects. Therefore, consistency between the wettability of nanoscopic defects and Cassie equation predictions might be expected. The hysteresis mechanism outlined within this thesis can be quantitatively applied to macroscopic defects, whereas its application to micro and nanoscopic defects is qualitative. / Finally, several applications of this fundamental research, which are directly related to real systems, have been outlined. These include mineral flotation, oil recovery, liquid movement, directed crystallization, Secondary Ion Mass Spectrometry for flotation analysis and patterning of inorganic surfaces. / Thesis (PhDApSc(MineralsandMaterials))--University of South Australia, 2004.