The Fischer-Tropsch process in South Africa, used for producing chemicals from synthesis gas, which is mostly derived from the gasification of coal, gives a large amount of medium chain length alkanes (C4-C8), which have little commercial value. Internationally, industry has recently placed more focus on the conversion of alkanes to value-added products. Two important routes to achieving this are dehydrogenation and oxidative dehydrogenation. The latter is an economically feasible route, in which there is growing interest by the international research community, and was investigated in this study. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2007.

No abstract available. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2006.

In this study, two plant species, Schefflera umbellifera (Araliaceae) and / Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2007.

The ability to construct C-N bonds is of great importance to organic chemists as exemplified by the vast number of natural products, pharmaceutical agents and fine chemicals that contain such linkages. An atom efficient C-N bond forming reaction namely hydroamination has attracted much interest to date due to its ability in forming amine, imine and enamine functionality. The scope of this project involved the attempted synthesis of a biologically active and nitrogen containing pyrrolizidine alkaloid isolated from cryptic thief ants and poison dart frogs namely 223H (xenovenine). The method of hydroamination was utilized as the pivotal ring forming step and was established as being a valuable synthetic tool towards the construction of 223H (xenovenine). The stereoselective synthesis resulted in the successful formation of ethyl (3R)-5-heptyl-3-methyl-2,3-dihydro-lH-pyrrolizine-7-carboxylate 74, a novel, and structurally analogous precursor to 223H (xenovenine) over 10 synthetic steps from (S)-pyroglutamic acid. The following research also resulted in the synthesis of two other novel compounds namely ethyl 3-[(2R)-2-methyl-5-thioxotetrahydro-lH-pyrrol-l-yl]propanoate 86 and ethyl 3-{(5R)-2-[(E)-2-ethoxy-2-oxoethylidene]-5-methyltetrahydro-lH-pyrrol-l-yl}propanoate 87. A catalytic hydroamination study on the conversion of C-propargyl vinylogous amides into pyrroles demonstrated that transition metal salts of groups 11 and 12 serve as effective hydroamination catalysts. The oxide, acetate, chloride and nitrate derivatives of group 11 and 12 metals namely Cu(II), Ag(I), Zn(II), Cd(II) and Hg(II) were employed as potential hydroamination catalysts in the oxidation states provided. The Zn(II) catalyst series with the exception ZnO provided the greatest hydroamination yields under mild reaction conditions owing to their high Lewis acidities however the Ag(I) and Hg(II) catalyst series also provided excellent yields of product under more forcing reaction conditions. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Computational studies have shown that cage skeletons (7) have the tendency to impose a 310-helix as well as an áL-helix on the polypepeptide chain. Residues such as 7 are the useful tools for study of the conformational preferences of peptide models, the design of peptide analogues with improved pharmacokinetics profiles and the development of pharmacophore models. Synthesis of pentacycloundecane amino acid analogue suitable for peptide synthesis would enable us to verify the computational predictions and to contribute to this very active field of research. The sterically hindered 8-amino-pentacyclo[5.4.0.02,6.03,10.05,9]undecane-8-carboxylic acid (7) was synthesised by hydrolysis of the novel bis-Boc protected pentacycloundecane-hydantoin (30). Progress to incorporate 7 into a non-natural peptides is reported. A computational investigation on the regioselective acetylation of hydantoin derivatives which includes PCU hydantoin, 5.5-dimethylhydantoin and 5-methylhydantoin is also reported. The results of the computational investigation initiated the regioselective synthesis of the mono-Boc and bis-Boc derivatives of 5,5-dimethylhydantoin and 5-methylhydantoin. These compounds have not been reported before. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2005.

No abstract available. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Chapter One serves as an introduction to, and background information, on the thermal decomposition of metal oxalates and homonucleus carbonyl clusters. Emphasis is placed on the compounds under investigation, namely the oxalates of iron(II), cobalt(lI) and nickel(ll) oxalate dihydrate and their corresponding binary and ternary compounds, as well as triiron dodecacarbonyl and tetracobalt dodecacarbonyl. Topics specifically addressed are their structures as well as the thermodynamics of the dehydration and decomposition of compounds of this type. Given this background, the overall aims of the work are presented. These include finding the reaction conditions to form metal powders from metal oxalates, and a preliminary study of carbonyl clusters to see if they too may be used in the production of metal powders. Chapter Two gives the results of the dehydration and decomposition of the metal oxalates, characterised by way of infrared, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. The compounds under investigation are those of the single oxalates of iron, cobalt and nickel; the binary systems of Fe-Co, Fe-Ni and Co-Ni, in the molar ratios of 3:1, 1:1 and 1:3 for each system; and the ternary oxalate system in the molar ratios of Fe1 :Co1 :Ni1, Fe8:Co1 :Ni1, Fe1 :Co8:Ni1 and Fe1 :Co1 :Ni8. It was found that under certain reaction conditions all these compounds, excluding the ferrous oxalate dihydrate, decompose to the metal. It was found through experiments to modify the morphology of the crystals under investigation that the decomposition product is controlled by the crystal lattice system the starting material is synthesised in. When in the cobalt/nickel oxalate a-crystal system, decomposition is to the metal, or in the case of the binary and ternary systems, to the alloy. If the oxalate is synthesised in the crystal system of the iron oxalate, the resultant decomposition product is the respective oxide. Experiments were carried out on the iron/cobalt binary system to prove this hypothesis. Depending on the conditions of synthesis, the iron/cobalt binary system can form in either the crystal system analogous to iron (1), or analogous to cobalt (2). The products of pyrolysis for each case differs, with (1) decomposing to the oxide and (2) decomposing to the alloy. iii Chapter Three is a brief, preliminary study describing the thermal decomposition of triiron dodecacarbonyl and tetracobalt dodecacarbonyl. Characterisation of the pyrolysis products is given by infrared, scanning electron microscopy, X-ray diffraction and thermogravimetric analysis. A tentative theory for their decomposition route under an atmosphere of nitrogen is given. It was found that neither compound decomposed fully to the central metal, but that a mixture of oxide and metal were left. The conclusion reached from this study was that neither carbonyl under investigation was particularly successful. Although in both instances metal was produced, both contained large amounts of the respective oxide. This makes them unsuitable for an industrial application to form metal powders. Chapter Four describes in detail the all the experimental, materials, methods, techniques and equipment used in this study. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2001.

The aim of this study was to investigate the electrochemical and electrocatalytic properties of a selection of glassy alloys for the hydrogen evolution reaction in base. The glassy alloy compositions tested included the known alloys Fe67Co18B14Si1, Co66Fe4Si16B12Mo2, Fe40Ni40B20 and Fe40Ni40P14B6 and an entirely new alloy Zr74Ti19Cu2Fe5. The electrochemical techniques employed were cyclic voltammetry and slow sweep polarisation. Electrochemical techniques were used in conjunction with the surface analysis techniques of scanning electron microscopy (SEM) and energy dispersive x-ray spectrometry (EDS) to gain insight into the morphology and chemical compositions of the electrode surfaces after various treatments. The aims included: 1) To obtain an understanding of the field of electrochemistry of glassy alloys. 2) To develop systems, techniques and procedures to enable the testing of a new alloy to be performed with confidence. 3) To this end, techniques were firstly developed and then compared with published data on the known alloys. Once the handling techniques were satisfactory the new and previously untested Zr74Ti19Cu2Fe5 glassy alloy was characterised, in particular its catalytic properties and its corrosion resistant properties were investigated. The physical properties of the Zr74Ti19Cu2Fe5 alloy are under investigation by another group in the School of Physics. My findings are presented here. The corrosion resistance of the alloys was determined in their as-polished state and after surface pretreatment from slow sweep anodic polarisation studies and cyclic voltammetry. Glassy Fe67Co18Bl4Si1 and Co66Fe4Si16B12Mo2 displayed the poorest corrosion resistance of the alloy compositions tested. The anodic polarisation curve of the Zr74Ti19Cu2Fe5 alloy produced no active region and displayed potentially excellent anticorrosive properties in the basic media which was attributed to highly passivating Zr oxide and Ti oxide surface films. The electrocatalytic activity of the glassy alloys for hydrogen evolution was evaluated in 1MKOH. Cathodic polarisation curves were used to construct Tafel plots from which the kinetic Tafel parameters, i0 and b, were calculated. The least corrosion resistant glassy alloy compositions, Fe67Co18B14Sil and Co66Fe4Si16B12Mo2, displayed the highest catalytic activity for hydrogen evolution in the as-polished state. The most corrosion resistant alloy, Zr74Ti19Cu2Fe5, showed the poorest catalytic activity for the reaction in the as-polished state and only a slight improvement was obtained by increasing the electrolyte temperature in comparison to the other alloys tested. This was again attributed to passivating Zr oxide and Ti oxide surface layers that inhibited the HER. It was found that the Zr-based alloy displayed no substantial advantages over the other glassy alloys or more expensive noble metal surfaces in basic media, unless pre-treated as described in this thesis. The influence of ex situ chemical pretreatment on the electrocataytic activity of the glassy alloys for the HER was determined using pure HF and HF/HNo3 mixtures. Acid pretreatment of glassy C066Fe4SiI6B12M02 and Fe40Ni40Pl4B6 with IM HF/lM HN03 (10 minutes) and Zr74Til9Cu2Fe5 with 1M HF (10 seconds) resulted in a significant improvement in the activity of the alloys in comparison to their as-polished state. SEM/EDS analysis indicated that preferential dissolution of a P-enriched surface region on the Fe40Ni40P14B6 electrode created a porous structure with a greatly enlarged surface area at which the HER could occur. In comparison, the P-free, Fe40Ni40B20, composition displayed a much lower improvement in activity after acid pretreatment with only slight surface roughening observed. The Zr component of glassy Zr74Ti19Cu2Fes was selectively leached by acid pretreatment to produce a porous surface, however, the corrosion resistance of the alloy was also reduced, as indicated from anodic polarisation curve that showed an active and passive region of greater current density than the as-polished electrode. Hence the beneficial effect of acid pretreatment in activating the alloy surface for the HER was countered by a reduction in the general corrosion resistance of the alloy. In view of the dramatic effect on the HER shown by prior ex situ (acidic) oxidation of the glassy alloy surface, the influence of in situ (anodic) oxidation in the basic medium was investigated for comparison. For all the glassy alloy compositions tested, anodic activation was found to be less effective than acidic activation. Anodic pretreatment of glassy Zr74Ti19Cu2Fe5 (3000µA.cm-2) resulted in the greatest improvement in activity in comparison to the as-polished state out of the alloy compositions tested. In addition, the corrosion resistance of the alloy was not reduced by anodic pretreatment and consequently formed a less destructive activation procedure than acidic pretreatment. In this regard, anodic pretreatment would produce a more durable electrocatalyst and is the preferred technique for activating the glassy alloy surfaces for the HER. Initial characterisation of the surface deposits formed by anodic oxidation, using SEM and EDS techniques, indicates that the composition of these deposits and the mechanism by which anodic activation activates the glassy alloy surfaces requires further investigation. / Thesis (M.Sc.)-University of Natal, Durban, 1999.

Amino acids are important building blocks for the synthesis of a large number of biologically active compounds and drugs. Amino acids with the pentacyclo-undecane (1) and trishomocubane (2) frameworks fall into the class of conformationally constrained non-natural amino acids. Conformationally constrained amino acids are found in many naturally occurring, biologically active compounds. It was found that incorporating cage structures into drugs induces a range of positive effects: promotes transport across the cell membrane, drugs can be designed to target the central nervous system, increased receptor site specificity, and retards metabolic degradation. In the light of this, it was decided to investigate the incorporation of cage amino acids into peptides. A synthetic route has been established for the efficient synthesis of amino acids 1 and 2, and for their incorporation into peptides. Several chiral macrocyclic crown ethers and related analogues have been shown to be capable of forming complexes enantioselectively with chiral organic ammonium salts. The design and synthesis of host chiral macrocycles which are able to distinguish between the enantiomers of guest organic ammonium salts is of interest in the areas that include synthesis of enzymes, electrodes for specific ions or molecules, drugs targeted for specific sites, and enantiomer separation. A synthetic procedure has been established for the synthesis of cage annulated chiral crown ethers derived from amino acids. The advantage of using cage compounds in crown ethers is due to increased rigidity, increased solubility in non-polar solvents and increased chirality. Various techniques for the determination of enantiomeric recognition have been studied and include NMR spectroscopy, fluorescence emission spectroscopy and computational methods. The cage crown ether 3 represents a typical example of these new cage annulated, chiral crown ethers. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

This work is aimed at elucidating the structures and spectroscopic properties of phosphine and b phosphonite complexes of Mn(III), Co(III) and Rh(III) porphyrins, a class of coordination compounds that has been little reported on in the literature to date. In this work, a range of novel bis(phosphine) and bis(phosphonite) complexes of the three aforementioned metals have been synthesized, crystalized and analysed by means of X-ray structure determination, 1H NMR, 13C NMR, 31P NMR as well as electronic and IR spectroscopy. [Mn(TPP)(PPh3)2](SbF6) crystallizes in the monoclinic space group P21/c and displays an extraordinarily long Mn-P bond length of 3.088(2) A. Moderate ruffling of the porphyrin ligand is observed. This complex is paramagnetic with fast proton relaxation times, and thus did not yield any useful 1H NMR data. In an attempt to crystallize [Mn(TPP){P(OPh)3}2](SbF6), a complex bearing an O-donor contamination product, [Mn(TPP){(O)PH(OPh)2} ](SbF6), was isolated and its solid state structure determined by X-ray diffraction methods. The structure of this complex has been included in this work as it displays interesting structural features and is the very first phosphonate complex of a metalloporphyrin. This compound crystallizes in the monoclinic space group P21/n and shows a significantly saddled conformation. The axial Mn-O bond length measures 2.122(3) A. The Mn-Nporph bond lengths are 1.998(6) and 2.002(3) A for the bis(phosphine) and phosphonate complexes, respectively. Since the diethyl phosphonate complex was an unintended reaction product, no further characterisation of it was undertaken. [Co(TPP)(depp)2](SbF6), where depp = diethylphenylphosphine, crystallizes in the monoclinic space group P21/c. This complex displays inversion symmetry at the metal center and the porphyrin core is effectively planar. However, [Co(TPP)(edpp)2](SbF6), where edpp = ethyldiphenylphosphine, crystallizes in the· monoclinic space group P21/n and shows a significantly ruffled conformation of the porphyrin core and displays no inversion symmetry. [Co(TPP)(deppt)2](SbF6), where deppt = diethylphenylphosphonite, also crystallizes in the monoclinic space group P21/n, but displays inversion symmetry through the central cobalt ion. As a result, this complex does not display any significant conformational deviations of the porphyrin core from planarity. The axial Co-P bond lengths are significantly shorter than that of . the equivalentbond in the manganese bis(triphenylphosphine) complex at 2.312(1) A, 2.323(10) A and 2.258(2) A for [Co(TPP)(depp)2](SbF6), [Co(TPP)(edpp)2](SbF6) and [Co(TPP)(deppt)2](SbF6), respectively. The Co-Nporph bond lengths average to 1.980(3) A, 1.972(7) A and 1.980(4) A for these three complexes, respectively. I03Rh NMR measurements of three rhodium bis(phosphine)/bis(phosphonite) porphyrins have been performed by the indirect probing of the rhodium metal center by means of the phosphorus nucleus of the coordinated axial ligand. The resulting I03Rh NMR shifts for [Rh(TPP)(edpp)2](SbF6), [Rh(TPP)(edppt)2](SbF6), where edppt = ethyldiphenylphosphonite, and [Rh(TPP)(deppt)2](SbF6) are 2558, 2413 and 2365 ppm, respectively. [Rh(TPP)(edpP)2](SbF6) crystallizes in the monoclinic space group P21/n and shows moderate ruffling of the porphyrin core. The axial Rh-P bond length is 2.401(2) A. [Rh(TPP)(edppt)2](SbF6) and [Rh(TPP)(deppt)2](SbF6) both crystallize in the monoclinic space group P21/c. The porphyrin core of [Rh(TPP)(edppt)2](SbF6) displays a moderate degree of ruffling, as observed in [Rh(TPP)(edpp)2](SbF6), yet the axial Rh-P bond length is substantially shorter at 2.361(9) A. [Rh(TPP)(deppt)2](SbF6) exhibits the shortest Rh-P bond length of the three complexes at 2.332(2) A. The porphyrin core is mostly planar. The Rh-Nporph distances average 2.034(1) A for the S4-ruffled complexes and 2.044(3) A for the planar complex, the shorter distance in the ruffled derivatives being consistent with a distortion-induced compression of the Rh(III) ion. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2003