The project was concerned with studying the capability of a micellar-enhanced ultrafiltration system (MEUF) to remove platinum group metal ions namely Pt (lV) and Pd (ll) chloro anions from aqueous industrial waste effluents. South Africa has the world’s largest reserves of platinum group metals (PGMs) and other valuable metals such as manganese, chrome ores, titanium minerals etc. which are required for new automotive and other technologies, including fuel cells, catalytic converters and lighter components. The consistent loss with the industrial waste stream and the toxicological effects of these precious metals led to the need to develop new and effective methods to recover them from industrial waste effluents. With such a wide variety of fields where these PGMs are used and the failure of the traditional techniques namely sedimentation, fermentation etc. to effectively reduce or recover these highly toxic and precious metal ions prior to discharging industrial waste effluents, it is necessary to explore other techniques such as membrane technology that can be used to recover these valuable species from industrial waste streams. The present study involved the use of a cationic surfactant, viz cetylpyridinium chloride, which was introduced into an aqueous solution containing palladium and platinum metal anions. The surfactant forms charged micelles above a certain critical concentration value. The metal anions adsorb onto the available oppositely charged sites on the micelle surfaces and are then able to be retained by a suitable membrane. Hollow fibre ultrafiltration membranes with the MWCO of +/- 10 kD and +/-30nm pore size were used as a filter component in this study. For this MEUF system to be effective, it was vital that the anionic metal ion species adsorbed sufficiently onto the available oppositely charged sites of the micelles and that the micelles were retained efficiently by the membrane. Results obtained during the investigation made it possible to make certain predictions about the micellisation process. It was also found that, it was not only the metal ion: surfactant (M:S) ratio that was critical, but the presence of other electrolytes in the aqueous stream proved to have a huge impact on the capability of the MEUF system. Findings of this research study showed that the MEUF system using cetylpyridinium chloride (CPC) can be used to recover or retain Pt (lV) and Pd (ll) anions from industrial waste effluents. It was also found that PtCl6 2-, due to its greater adsorption capabilities onto the micelle surface than PdCl4 2- or PdCl3(H2O)-, was preferentially retained in neutral medium. This may be exploited as a possible means of separating the two metal ions. The developed system offers the following advantages over some traditional and current methods: simplified unit operation line flow process, smaller amounts of chemical usage and no solid toxic sludge to be disposed of. Applications of this work could be of vital importance in catalytic converter recycling, especially in Port Elizabeth where extensive automobile parts manufacturing occurs.

The preparation, characterization, and catalytic properties of some soluble and polymer-bound palladium and platinum complexes of ferrocene derivatives are described. Special emphasis has been placed on studies of the mixed "hard-soft" ligands such as PPFA and ISOPFA. [Formula Omitted] The soluble complexes (L-L)MC1₂ (L-L = BPPF, PPFA, ISOPFA, BPPFA; M = Pd, Pt) and [(L-L)PdS₂][C10₄]₂ (L-L = BPPF, PPFA; S = DMF, py) have been characterized by microanalyses, NMR and IR spectroscopic techniques. The cationic palladium(II) complex [(L-L)PdS₂][C10₄]₂ (L-L = PPFA, S = DMF) is an effective catalyst precursor for the hydrogenation of simple olefins at 30°C and 1 atm pressure. The rate of styrene hydrogenation depends on the substrate concentration, catalyst concentration and the solvent. The results are consistent with a homogeneous catalytic system. Platinum(II) complexes (L-L)PtCl₂ (L-L = (S,R)-PPFA, (S,R)-ISOPFA) are effective catalyst precursors for the hydrosilylation of aromatic ketones with Ph₂SiH₂. The complexes with mixed "hard-soft" ligands are better catalyst precursors than those with di(tertiary phosphine) ligands. Under the same conditions the hydrosilylation of ferrocenyl ketones results in further reduction and affords mainly the alkylferrocene products. The stable carbonium ion FcC⁺HCH₃ (Fc = Fe-(C₅H₅)(C₅H₄)-) is reduced by Ph₂SiH₂ to FcCH₂CH₃ in a thermal reaction which is catalyzed by the complex (PPFA)PtCl₂. The reaction of Ph₂SiH₂ with (L-L)PtCl₂ (L-L = PPFA, ISOPFA) yields a stable platinum(IV) hydride, which eliminates Ph₂SiHCl in solution to afford (L-L)PtHCl. The mechanistic implications of these observations are discussed. Polymers functionalized with ferrocene and ferrocene derivatives have been prepared. Mossbauer spectroscopic techniques and microanalyses are used to characterize these polymers and their palladium and platinum complexes. In a number of cases these results are confirmed by the cross-polarization/magic-angle spinning ¹³C NMR spectroscopic technique. The palladium(II) and platinum(II) derivatives of the ferrocenyl-amine and -phosphine containing polymers are effective catalysts for the hydrogenation and hydrosilylation of olefins. All the catalysts can be easily separated from the reaction mixture and can be recycled with no loss of activity. The pronounced effect of the attached ligand in the palladium based polymers indicates that free metal is not involved. However, in the case of platinum based catalysts, it is likely that reduction to platinum metal takes place. / Science, Faculty of / Chemistry, Department of / Graduate

D.Sc. (Chemistry) / Please refer to full text to view abstract

Ph.D. / The intramolecular insertion of allylpalladium species into alkene and alkyne bonds ('metalloene' cyclisation) of acetoxy-2,7-dienes and acetoxy-2-en-7-ynes has evolved into a synthetically powerful process. Proceeding from the favourable results obtained with achiral analogues, the palladium-catalysed 'metallo-ene' reactions of acyclic carbohydrate-derived 1,1-diacetoxy-2,7-diene and 1,1-diacetoxy-2-en-7-yne compounds proceeded in a stereospecific fashion to furnish chiral, multi-functionalised five-membered carbo- and heterocyclic products. A valuable consequence of the reactions of these geminal diacetate starting materials is that the products contain enolacetate, or latent aldehyde moieties. Further elaboration of these functionalities enables the facile entry to an array of substituted five-membered ring compounds, some of which have been identified as synthons or substructures of important natural products. In the presence of carbon monoxide (1 atm) the corresponding cyclic carboxylic acid products were obtained under mild 'metallo-ene' reaction conditions. Cyclised chloro componds were obtained by exposure of the 1,1-diacetoxy-2-en-7-yne substrates to Wacker-like conditions in the presence of an excess of LiC1. The highly atom economical Trost-type cycloisomerisation ensued when these enyne starting materials were stirred in acetic acid in the presence of a palladium(0) catalyst. The mechanism of the palladium-catalysed 'metallo-ene' transformations is discussed with respect to the enantioselectivity of carbopalladation of prochiral alkenes as well as the transition states. The topological influence of pre-existing centres over developing stereogenic centres is evaluated. Following indications that n-allylpalladium complexes can be prepared by the oxidative addition of Pd(0) to an a,13-unsaturated acetal, our next strategy was based on the use of suitably substituted A 2'3-pyranoside rings as chiral templates for the construction of multi-functionalised fivemembered ring systems via Pd-catalysed 'metallo-ene' cyclisations. Enantiomerically pure bi- and/or tricyclic products of carbonyl insertion were obtained in fair to good yields when these 'metallo-ene' reactions were conducted in the presence of CO under mild reaction conditions. Subsequently, bicyclic diene products were prepared via the palladium-catalysed cyclisation of Az3-C-glycoside derivatives. Important revelations concerning the relative stereochemistry of substrates for palladium-catalysed 'metallo-ene' cyclisation/carbonylation of unsaturated C-glycoside derivatives were made. The consecutive introduction of unsaturated C-alkyl side-chains at C-4 and C-1 of selected pseudoglycals via palladium-catalysed nucleophilic allylic substitution reactions accomplished the formation of chiral dienyne compounds. Palladium-catalysed cascade cycloisomerisation of these substrates effected the smooth synthesis of enantiopure tricyclic products. Cascade cyclisation of these highly unsaturated starting materials under Wacker-like conditions afforded [5,6,6]-tricyclic dichloro compounds. A mechanism to account for the stereospecific incorporation of two chlorine atoms into, and the ring expansion of the substrate carbon framework, is proposed. Finally, the readily accessible tert-butyl 6-0-acety1-4-[bis(ethoxycarbonyl)but-3-eny1]-2,3,4- trideoxy-a-D-erythro-hex-2-enopyranoside was converted, via a domino process, into a chiral substituted dihydropyran in the presence of a Pd(II)-catalyst in acetic acid/acetonitrile. By conducting the reaction under an atmosphere of CO, a tetrahydropyran compound containing a carboxylic acid side-chain was obtained, while the corresponding chloro product was prepared when the pseudoglucal starting material was exposed to an excess of LiC1 and CuC1 2 under Wacker-like conditions.

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The main objective of this investigation was to study palladium-catalyzed coupling of 2-aryl-4-chloro-3-iodoquinolines with phenyl boronic acid in order to assess the regioselectivity of carbon-carbon bond formation at either C3 or C4. The 2-aryl-4- chloro-3-iodoquinolines were subjected to Pd(PPh3)4-catalyzed coupling reaction with phenyl boronic acid in DMF in the presence of 2M sodium carbonate (aq) to afford 2,3-diaryl-4-chloroquinolines. Reaction of 2,3-diaryl-4-chloroquinolines with sodium methoxide in MeOH-DMF mixture under reflux afforded the corresponding 2,3-diaryl-4-methoxyquinoline. An alternative route to the latter involving palladiumcatalyzed cross-coupling reaction of 2-aryl-3-iodo-4-methoxyquinolines derived from the reaction of 2-aryl-4-chloro-3-iodoquinolines with sodium methoxide in refluxing methanol-THF mixture was also investigated. The 2,3-diaryl-4-methoxyquinolines were subjected to further studies of chemical transformation with boron tribromide to afford the corresponding 2,3-diarylquinolin-4(1H)-ones. All new compounds were characterized using a combination of NMR (1H and 13C), IR and mass spectroscopic techniques as well as elemental analysis. / Chemistry / M. Sc. (Chemistry)

M.Sc. (Chemistry) / Please refer to full text to view abstract

Yu Michael. / Thesis submitted in: July 2003. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 57-63). / Abstracts in English and Chinese. / Table of Contents --- p.i / Acknowledgments --- p.iii / Abbreviations --- p.iv / Abstract --- p.v / Chapter Part I - --- Optimization of Palladium Catalyzed Phosphination / Chapter Chapter 1 --- General Introduction / Chapter 1.1 --- Background of Phosphine Synthesis --- p.1 / Chapter 1.2 --- Preparation of Phosphines --- p.4 / Chapter Chapter 2 --- Optimization of Phosphination of Aryl Bromides / Chapter 2.1 --- Additive Effect in Phosphination of Aryl Bromides --- p.14 / Chapter 2.2 --- Iodide Effect in Phosphination of Aryl Triflate --- p.25 / Chapter 2.3 --- Low Temperature Phosphination --- p.27 / Chapter 2.4 --- Conclusion --- p.29 / Chapter Part II - --- Synthesis of Optically Active As，N Ligands and Their Metal Complexes / Chapter Chapter 1 --- 3.1 Introduction --- p.30 / Chapter Chapter 2 --- Synthesis of Optically Active As，N Ligands and Their Metal Complexes / Chapter 4.1 --- "Synthesis of As,N Oxazolines" --- p.39 / Chapter 4.2 --- "Synthesis of As,N Oxazoline Transition Metal Complexes" --- p.41 / Chapter 4.3 --- Conclusion --- p.44 / Experimental --- p.45 / References --- p.57 / Appendix --- p.64

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xii, 218 p. : ill. Includes abstract. Includes bibliographical references (p. 118-123).

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