A dissertation submitted to the Faculty of Science for the degree of Master of Science University of the Witwatersrand, Johannesburg / It is well known that chlorinated organic compounds behave as highly toxic substances in the environment. Catalytic hydrodechlorination .... one of the more convenient approaches used to treat chlorinated organic substances with the aim of obtaining compounds with lower or null toxiciy. Further, the selective cleavage of the C-Cl bond plays a key role in processes related to the manufacture of fine chemicals. These reactions can be performed over noble-metal catalysts, either in the gas or liquid phase. (Abbreviation abstract) / Andrew Chakane 2018

Versatile polyelectrolytes with tunable physical properties have the potential to be transformative in applications ranging from medicine to energy storage. To expand the design space for innovative cationic polymeric materials, I describe herein the development of a new class of functional polyelectrolyte based on the aromatic trisaminocyclopropenium (TAC) ion. The facile synthesis of a series of cyclopropeniumbased macromolecules via either the direct polymerization of functional monomers or a post-polymerization click reaction is demonstrated. To probe fundamental structureproperty relationships and understand technological implications of cyclopropenium polymers, a variety of materials were evaluated as gene delivery agents for cellular transfection and as ion conducting membranes. It was found that certain cyclopropenium polymers are biocompatible and efficient transfection agents, and that post polymerization functionalization chemistry enabled the straightforward screening of polymeric TAC derivatives. Furthermore, the thermal properties, local morphology, and dielectric response of a series of monomeric and polymeric TAC ionic liquids with different counter ions were characterized. It was found that the mechanism for ion transport depends on the nature of the ion pair, which can promote anomalously high conductivity at the calorimetric glass transition temperature. Finally, the synthesis of a new class of polyelectrolyte based on the cyclopentadienyl aromatic anion is described.

Petroleum hydrocarbons are emitted into the environment via natural and anthropogenic activities. Once emitted, these hydrocarbons can be transported globally, persisting and accumulating in aquatic ecosystems. In the Alberta oil sands region (AOSR), mining activities have significantly altered and polluted the surrounding aquatic and terrestrial environments with heavy metals and various petroleum hydrocarbons including polycyclic aromatic hydrocarbons (PACs). Though PACs have been tracked through time using dated lake sediment cores, separating natural and anthropogenic PACs can be difficult. In the Peace Athabasca Delta (PAD) this task is especially difficult as this region has been receiving annual inputs of naturally eroded bitumen throughout history. Petroleum biomarkers are unique petrogenic compounds (i.e. derived from petroleum) which may provide a secondary proxy to track mining impacts. This thesis investigated the impacts of mining activities on the AOSR and the PAD using two different proxies, PAC and petroleum biomarkers. These two regions were compared to reference lakes to the south and northwest of the Athabasca oil sands formation, in order to provide a natural signal, with minimal oil sands mining contamination. Historically deposited PACs and petroleum biomarkers were analysed in radiometrically dated lake sediment cores from the AOSR and the PAD, Alberta. Sediment profiles in the AOSR (Saline Lake) showed increases in PAC fluxes for both alkylated and parent compounds coeval with mining activities. Alkylated PAC fluxes in reference lakes (Mariana Lake and BM11) increased at the height of oil sands development (1990s). PAD lakes showed no statistical increase in PAC flux through time due to high levels of naturally eroded bitumen entering the system. Parent PAC diagnostic ratios, however, showed clear shifts from pyrogenic (primarily wood burning) in pre-development sediments to petrogenically derived PACs in modern sediments, in both AOSR and PAD lakes, coeval with oil sands development. Petroleum biomarker diagnostic ratios in Saline Lake and PAD lakes remained stable through time, indicating a clear current and historical petroleum signal originating from the AOSR. Reference lakes (Mariana Lake and BM11) showed the greatest change in petroleum biomarkers. Historically, these lakes had signatures uncommon of petroleum sources, however, in recent years petroleum inputs from mining development were revealed by these petroleum biomarkers. This study compared the historical trends of several petroleum hydrocarbons in lake sediment to the historical emissions of these petroleum hydrocarbons from oil sands mining operations. Notably, we show the potential for petroleum biomarkers to trace petroleum hydrocarbon contamination in the environment.

The photodebromination of selected bromoarenes has been studied at 300 nm to determine the the possible mechanistic pathways leading to product. Irradiation of 4-bromobiphenyl (BpBr) at this wavelength leads to the product biphenyl. The quantum yield of intersystem crossing (0.98) and quenching studies with cis-1 ,3-pentadiene suggest that the reaction occurs only via the triplet state. The observed increase of quantum yield of reaction with increasing concentration of BpBr suggests formation of a triplet excimer between the triplet state and ground state of BpBr as the key reactive intermediate. The log of the rate constant for excimer formation showed a linear increase with solvent polarity. The correlation of rate constants for excimer formation with linear solvation energy parameters indicates only a weak polarization of the excimer species. In order to understand the extent of radical anion character in the excimer, the regiochemistry of the photo-debromination of 3,4-dibromobiphenyl (3,4-BpBr) was studied. 3,4-BpBr was irradiated with and without an electron donor (triethylamine). 3,4-BpBr was also chemically reduced with lithium biphenylide (LiDBB). The difference in the regiochemistries under these conditions has been interpreted in terms of reaction via a free radical anion in the case of reactions with triethylamine and LiDBB and a weakly polarized excimer in the case of direct irradiation. In order to understand the extent of polarization in the excimers and their conformation, it was decided to study systems where the structure of the molecule would fix the geometry of potential intramolecular charge-transfer complexes. Towards this goal, brominated [2.2]paracyclophanes, 4-bromo[2.2]para-cylophane (CpBr), pseudo-para-dibromo[2.2]cyclophane (ps-p-CpBr) and pseudo-ortho-dibromo[2.2]cyclophane (ps-o-CpBr), were studied. The effect of substitution pattern of the bromines on the efficiency of excimer formation was also investigated. The brominated [2.2]para-cyclophanes showed varying efficiencies of formation of intermolecular excimer and intramolecular charge-transfer. A probable conformation for the excimer from BpBr has been proposed based on these results. / Graduation date: 1991

No description available.

Thesis (M.Sc.)--Memorial University of Newfoundland, 2000. / Bibliography: leaves 105-119.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 173-178). Available also in a digital version from Dissertation Abstracts.

Thesis (Ph. D.)--University of Missouri-Columbia, 2001. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (M. Sc.)--University of Hong Kong, 1964. / Typewritten.