The aim of this research project was to investigate the oxidation reactions of olefins to ketones. Initial studies revolved around the oxidation reactions of terminal olefins to symmetrical dialkyl ketones. The inability to isolate pure products, and the consumption of large amounts of the expensive palladium catalyst for each run as well as the extremely low yields that resulted from these oxidation reactions, made it difficult to thoroughly investigate this oxidation system. It was then decided to embark on the investigation of oxidation reactions of a-olefins to methyl ketones. For these studies, six terminal olefins were oxidised to methyl ketones employing seven different oxidation reactions. One of the most important and pioneering reactions m this field is the system employing PdCl2 / CuCl2 / O2 for the oxidation of terminal olefins to methyl ketones, namely the Wacker oxidation reaction. Experimental results, however, indicated that high product contamination from by-products resulted from these oxidation reactions despite the fairly good yields of product from the Wacker oxidation system. Some reaction systems that have been developed from the Wacker oxidation system were also investigated. The oxidation system employing PdCl2 / p-benzoquinone for the oxidation of terminal olefins to ketones was studied. The oxidation reactions resulted in incomplete oxidation with higher olefins (l-decene, l-nonene and l-octene), and complete oxidation of lower olefins (l-heptene, l-hexene and l-pentene) under the same reaction conditions. The products from lower olefins oxidised under these reaction conditions were pure and high yielding Another system that proved efficient both with feasibility and good yields of products was the oxidation system employing Pd(OAc)2 / H202 catalyst to oxidise terminal olefins to methyl ketones. Phase transfer catalysis has been employed in organic chemistry to effect different reactions. In this case two types of phase transfer agents were employed to effect the oxidation of terminal olefins to ketones. The first oxidation system involved the use of a PdCl2 / CuCl2 / O2 catalyst with a quaternary ammonium salt, cetyltrimethylammonium bromide (CTAB), to govern the course of the reaction. Reasonable yields were obtained, and moderate purity of products was also observed. The second phase transfer catalysis system employed polyethylene glycol (PEG-200) as a phase transfer agent, and PdCl2 / CuCl2 / O2 as a catalyst for oxidation of olefins to ketones. This oxidation system resulted in different isomers of a ketone from a terminal olefin. Pure methyl ketones were not isolable from the mixture of methyl and ethyl ketones. The oxidation reactions of olefins to ketones employing Pd(OAc)2 / p-benzoquinone in combination with electrolysis were also investigated. The unique feature about these reactions was the fact that cyclic olefins could also be oxidised under these conditions. Good yields were obtained, and high product purity was observed. One of the important oxidation reactions investigated during the project was the reaction that used an alternative metal to the expensive palladium catalyst for the oxidation reactions to ketones. This oxidation system employs CuCl2 / 18-C-6 / acetaldehyde as a catalyst for the oxidation of hydrocarbons to ketones and alcohols. It was discovered during the investigation that olefins can also be used as substrates and are oxidised to the corresponding ketones. The use of olefins as substrates resulted in higher yields than the hydrocarbon oxidation reactions, and less contamination in the product mixture was also observed. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.

This thesis is presented in two parts. In part one, the excess molar volumes and the excess molar enthalpies have been determined for several binary systems at 298.15 K using an LKB flow microcalorimeter and/or a 2277 Thermal Activity Monitor and an Anton Paar Digital Densitometer. The excess molar volumes and excess molar enthalpies, V; and H; , have been determined for systems involving an alkanol (I-propanol, 2-propanol) mixed with a hydrocarbon (1hexene, I-heptene, l-octene, I-hexyne, I-heptyne, l-octyne). The results show trends relating to the degree of unsaturation of the hydrocarbon to the position of the hydroxyl group on the alkanol. The excess molar volumes and excess molar enthalpies, V; and H; of di-n-butylamine + diethyl ether or dipropyl ether or di-l-methylethyl ether or dibutyl ether or 1,1 dimethylethyl methyl ether or 1,1 dimethylpropyl methyl ether or tetrahydrofuran or tetrahydropyran or 1,4 dioxane have been measured over the whole composition range at the temperature 298.15 K in order to investigate di-n-butylamine - ether interactions. The V; values for each of the systems studied are negative with the exception of the mixtures of (di-n-butylamine + dibutyl ether or tetrahydrofuran or tetrahydropyran or 1,4 dioxane. The H; results over the whole mole fraction range are formed endothermically. Measurements were also made on mixtures involving (a cycloalkane + a pseudocycloalkane). The congruency theory was tested for the (cycloalkane + pseudo-cycloalkane) mixture. The cycloalkane mixtures studied here did not satisfy the null test of the congruency principle. In the second part of this thesis the main aim of the investigation was to apply ambient temperature hydrogen peroxide bleaching techniques to a novel non-woven fabric and to optimize the treatment conditions for this technique. Five cold-pad batch bleaching formulas were applied to the non-woven and the sample fabrics were analyzed for the following properties a) fluidity (measure of degree of degradation of the cotton fibre as a result of the bleaching process) b) wettability (absorbency) c) whiteness (using instrumental techniques) d) inherent fibre surface properties (SEM) A method was elucidated for the cold batch bleaching of the non-woven which produced a fabric with minimum fibre damage, an acceptable degree of whiteness and excellent absorbency properties. The treatment parameters of time (Xl), temperature(x2) and hydrogen peroxide concentration (x3) for this method were optimised using a multiple regression analysis for three variables and response surface plots. / Thesis (M.Sc.)-University of Natal, Durban, 1993.

The wood, leaf and seed extracts of Apodytes dimidiata, Turraea floribunda and Turraea obtusifolia were examined. Two new limonoids belonging to the Toonafolin group were isolated from the seeds, two known havanensin-type limonoids were isolated from the leaves and both stigmasterol and sitosterol were isolated from the wood of Turraeafloribunda. Sitosterol as well as a limonoid which could not be characterised were isolated from the seeds, phytol, melianone and a protolimonoid similar to sapelin-F were isolated from the leaves and three protolimonoids: melianodiol, melianotriol and 7,8-dihydroturraeanthin 3-acetate were isolated from the wood of Turraea obtusifolia. An ester was isolated from the seeds of Apodytes dimidiata. Appropriate reactions were performed, where possible, on the compounds isolated. / Thesis (M.Sc.)-University of Natal, Durban, 1990.

An investigation has been carried out to determine the effects of the dissolved solids in process cooling water (pcw) and mine water (mw) on concrete corrosion. An experimental set up was designed to simulate the process in the cooling towers of Sasol (Pty) Ltd at Secunda. The investigation was carried out using Ordinary Portland Cement (OPC) and Portland Blastfurnace Cement (PBFC). The corrosion process was monitored as a function of time by determining the concentrations of the ions left in solution. This was done using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) and Ion Chromatography (lC). The observation, identification and characterization of the secondary phases formed during the corrosion process were analyzed using the Scanning Electron Microscopy(SEM). Energy Dispersive X-ray Microanalysis (EDX) made it possible to identify the various microstructures and quantify their elemental composition. This made it possible to monitor the penetration of sulphate ions in the mortar. Powder X-ray Diffraction (XRD) qualitative analysis was also performed on the test mortar specimens. The organic constituents in process cooling water were determined using Gas Chromatography coupled with a Mass Spectrometer (GC-MS). The corrosion indices which measures the aggressiveness of water solutions towards cement and concrete were calculated for both process cooling water and mine water. The results of the investigation showed that mine water is more corrosive than process cooling water. This observation has been linked to the presence of the organic compounds in process cooling water. The results also indicated that PBFC was mores resistant to chemical attack than ope. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

This work was undertaken to investigate the transpassive behaviour of the anodic film on two Fe-Cr alloys, namely Fe18Cr and Fe18Cr2Mo in acidic aqueous media in the pH range 0.5 to 3.8. Two electrochemical techniques were used, namely cyclic voltammetry and chronoamperometry. The two primary experimental variables in the cyclic voltammetric experiments were pH and sweep rate (2 - 800 mV/s). The main variables in the chronoamperometric experiments were the size of the potential step, the number of potential steps and the starting and ending potentials. Secondary experimental variables were temperature (25, 90°C), rotation rate (0, 150 rad/s), and the artificial addition of cations (Fe2+, Fe3+ and Cr3+) to some of the solutions. A voltammetric anodic peak, referred to as peak A, occurs in the transpassive region of the above Fe-Cr alloys, followed by a region of secondary passivity and then oxygen evolution. It was this peak that was investigated by cyclic voltammetric methods. The peak A current response was independent of rotation rate at pH 3.8 but was dependent on rotation rate at pH 0.5 with solutions of intermediate pH showing a gradual change in rotation rate dependence. This indicated a predominantly solid state process in less acidic solutions (pH 2.4 & 3.8) whereas in strongly acidic solutions (pH 0.5) the action of ions in solution must contribute significantly towards peak A processes. A method was developed to correct the peak A current response for the current due to oxygen evolution. The results of this method indirectly confirmed the hypothesis that more than one oxidation process contributes to the peak A current response. A diagnostic plot for diffusion control was applied to the peak height of peak A. The diagnostic involves plotting the peak height over the square root of the sweep rate versus the square root of the sweep rate. A process under diffusion control would give a horizontal line for this diagnostic plot. At pH 0.5 and at slow sweep rates (less than or equal to 60 mV/s) the diagnostic plot gave a positive deviation from the horizontal and this deviation was enhanced as the temperature was increased. As the pH was increased (towards pH 3.8), the deviation from the horizontal at slow sweep rates gradually became negative and this deviation was again enhanced when the temperature was increased. This phenomenon is explained in terms of the role of the hydronium ion. From the addition of Fe2+, Fe3+, and Cr3+ to pH 0.5 and pH 3.8 solutions it was noted that ferrous ions increased the peak A current response more than chromic ions of the same concentration. Ferric ions slightly decreased the peak A current response. Based on these results, reports in the literature, and the apparent role of the hydronium ion, a partial scheme was proposed in order to explain the role of Fe and Cr, from the alloy substrate, in the anodic film in the transpassive region. In chronoamperometric experiments, stepping to the transpassive region confirmed the phenomenon of the rising transient. A quantitative nucleation model - which was based on previous models from the literature - was generated. The model was successfully fitted to two rising transients, one from the pH 3.8, and the other from the pH 0.5 solution. The model also allows for the presence of a pre-existent laver at the starting potential of a chronoamperometric experiment after the electrochemical cleaning procedure. The model incorporates both diffusion controlled and charge transfer controlled steps. A key concept in the model is that of nucleation and "slow death" of corrosion pits growing into the electrode. "Death" of a pit occurs when it is covered by a nucleating and or growing passivating film. The rising transients were only obtained on Fe-Cr alloys (with one exception) when stepping to the transpassive region and also only in solutions where peak A was obtained in a cyclic voltammetric experiment. The exception to this was that in the pH 0.5 solution and at 90°C, rising transients were obtained when stepping to the passive region. This did not occur at 25°C. Rising transients were also obtained on pure iron when stepping to the passive region. In addition to the rising transient, a reverse rising transient was discovered. This reverse rising transient (which generated a cathodic current) was obtained when stepping the potential cathodically from the transpassive region. It was shown that the occurrence of the reverse rising transient was dependent on the presence of a stable, transpassive anodic film before the potential step. One indirect result from the discovery of the reverse rising transient was that it indicates that secondary passivity exists at least 200 mV into the oxygen evolution region. / Thesis (M.Sc.)-University of Natal, 1993.

Ledebouria zebrina and Scilla natalensis Planch were the two species investigated in this work. Ledebouria zebrina belongs to the Hyacinthaceae (Liliacea sensu lato) and to this date, the chemical composition of this species has not been investigated. Members of this family are found in southern Africa. The Ledebouria genus was formerly classified as part of the Scilla genus from which a large member of naturally occuring oxygen heterocycles known as homoisoflavanones have been isolated. In this work the bulbs of L. zebrina were investigated and five compounds were isolated. Three compounds were of the homoisoflavanone type while the remaining two belong to the eucosterol type triterpernoids. Scilla natalensis Planch also belongs to the Hyacinthaceae family. Previous chemical investigations of the bulbs of this plant yield two homoisoflavanones of the 3-benzyl-4- chromanone type. Members of this family are mostly found in the Eastern parts of the country, ranging from the Eastern Cape to Mpumalanga province including Lesotho and Swaziland. The bulbs of this plant were investigated and this yielded ten compounds. The structures of the isolated compounds were elucidated using spectroscopic methods. / Thesis (M.Sc.)-University of Natal, Durban, 2001.

Two species belonging to different families were investigated, Eucomis montana from the Hyacinthaceae and Agapanthus inapertus from the Agapanthaceae. To date no previous chemical investigation on Eucomis montana has been reported. Eucomis species are routinely harvested, processed and sold for the treatment of various ailments ranging from toothache, gastro-intestinal ailments, pain-producing ailments and venereal and urinary diseases. Members of the genus have shown to contain steroidal compounds and homoisoflavonoids. In this work one nortriterpenoid, a eucosterol type derivative and eleven homoisoflavonoids belonging to four classes, the 3-benzyl-4-chromanone, the 3-benzyl-3-hydroxy-4-chromanone, the 3-benzylidenyl-4-chromanone and the scillascillin type were found in the bulbs of Eucomis montana. Agapanthus species are also used by a number of African tribes medicinally. The bulbs and rhizomes of this family have been reported to contain steroidal saponins and sapogenins. In this work the roots of Agapanthus inapertus have been investigated and a tignan precursor and a lignan have been found. Structures of the compounds isolated were determined using spectroscopic techniques. / Thesis (M.Sc.)-University of Natal, Durban 2003.

A series of five, tetradentate Schiff-base ligands were synthesised and chelated to vanadyl to form oxovanadium(IV) complexes. The ligands, 4,4’-{benzene-1,2-diylbis[nitrilo(1E)phen-1-yl-1ylidene]}- dibenzene-1,3-diol (H2L1), 4,4’-{ethane-1,2-diylbis[nitrilo(1E)phenyl-1-yl-1-ylidene]}dibenzene-1,3-diol (H2L2), 4,4’-{propane-1,2-diylbis[nitrilo(1E)phen-1-yl-1-ylidene]}dibenzene-1,3-diol (H2L3), 4,4’-{(2- hydroxypropane-1,3-diyl)bis[nitrilo(1E)phen-1-yl-1-ylidene]}dibenzene-1,3-diol (H2L4) and 4,4’-{2,2- dimethylpropane-1,3-diyl)bis-[nitrilo(1E)phen-1-yl-1-ylidene]}-dibenzene-1,3-diol (H2L5), characterised by TOF-MS, IR, electronic absorption, 1H and 13C NMR spectroscopy. The ligand H2L5 was also characterised by XRD. The ligands were shown to have a bis-zwitterionic structure in the solid state, and possibly also in solution. Complexes were characterised by Elemental Analysis, TOF-MS, IR, electronic absorption spectra, EPR and 51V NMR spectroscopy. They form mononuclear complexes, with one ligand binding a single vanadyl ion. EPR spectroscopy was performed on both the powdered form and solutions of the complexes. All the complexes displayed axial symmetry, with increasing distortion from an ideal square pyramidal geometry as the size and bulk of the central chelate ring was increased. Isotropic g0 values suggest solvent interaction with the vanadium ion for the coordinating solvent DMSO. Additional distortion on the coordination geometry, presumably from the benzyl groups of the compounds, causes the isotropic hyperfine coupling constants to be greater than expected. Furthermore, the ability of the complexes to bind peroxide species was investigated by following the addition of H2O2 to the complexes using 51V NMR spectroscopy to observe shielding changes at the vanadium nucleus, and 1H NMR spectroscopy to monitor the bulk magnetic susceptibility, via a modified Evan’s NMR method. Similar experiments were done with sodium hydroxide for comparison. As expected, the oxoperoxovanadium(V) complexes were more stable than their progenitor oxovanadium(IV) complexes. Additionally, increasing the distortion from the ideal pseudo square-pyramidal coordination geometry for the vanadyl ion resulted in a greater increase in the apparent stability of the peroxocomplexes. This latter effect is further enhanced by the addition of a hydrogen-bonding group in close proximity to the vanadium nucleus. DFT calculations of the optimized geometries, natural bond orbitals, electronic absorption and infra-red frequencies were performed for both the ligands and the complexes; nuclear magnetic resonance calculations were performed for the ligands as well. The B3LYP/6-311G (d,p) and B3LYP/LANL2DZ level of theories were used for the ligands and complexes respectively, except for electronic transitions, which were calculated using TD-SCF methods for both ligands and complexes. Calculated and experimental results were compared where possible, and showed reasonable agreement for all calculations performed. The exception to this was for the NMR calculations for the ligands, which were poorly simulated. Finally, the in vitro biological activity of the complexes was evaluated for cytotoxicity against the human tumour cell lines: A549, U251, TK-10 and HT29, via an MTT assay. All complexes showed promising anticancer activity, as evidenced by their low IC50 values for the cell lines A549, U251 and TK-10, which are in general, lower than that observed for cisplatin. They did, however, express negligible activity against the HT29 colon adenocarcinoma cell line; showing an apparent selectivity for certain cell lines. These oxovanadium(IV) complexes, thus warrant further evaluation as chemotherapeutic agents. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

A series of novel Bis 2,2':6',2″-terpyridinyl ligands, linked through a flexible alkyl chain situated at the 4' position, were synthesised and characterised by microanalysis, FTIR, NMR, UV-Visible spectroscopy, and MS-ToF. Single crystals of all the ligands were obtained, of which one has been published, one has been submitted for publication and one is in preparation for publication. These ligands were then coordinated to platinum(II) and characterised, including ¹⁹⁵Pt NMR spectroscopy. A detailed kinetic study involving the substituting the chloride co-ligand with the following nucleophiles thiourea, 1,3-dimethyl-thiourea and 1,1,3,3-tetramethyl-thiourea was conducted using stopped-flow techniques. An associative reaction mechanism was suggested for the pendant ligand substitution and the following trend in reactivity was observed: L2-Ptα > L3-Ptβ > L1-Ptχ. UV-Visible absorption spectra were recorded on sequentially diluted solutions of the ligands (in chloroform), and the platinum complexes (in water). These spectra obeyed the Beer-Lambert law. The values of the molar absorption coefficients at the wavelengths of maximum absorption for the ligands followed the trend L1 < L2 < L3, whilst for the complexes the trend was L1-Pt < L3-Pt < L2-Pt. It has been concluded that at low concentrations L2-Pt and L3-Pt undergo intramolecular folding. Variable temperature and variable concentration NMR spectroscopic studies were performed on all three complexes. At higher complex concentrations intermolecular self-association takes place for L2-Pt and L3-Pt but not for L1-Pt. The reactivity of the complexes is predominately determined by their structural conformations in solution. At low concentrations the L1-Pt complex remains in its linear conformational state, whilst the L2-Pt and L3-Pt complexes undergo intramolecular folding with the formation of an axial Pt—Pt bonded and π—π stacked dinuclear platinum terpyridine centre. The latter is believed to be more active in the substitution reaction than the original mononuclear centre. The reasons for the folding and self-association in the L2-Pt and L3-Pt systems are related to the steric crowding and stress in the spacer region of the folded or self-associated complexes. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Actinomycetes are bacteria belonging to the order of Actinomyceteles and are / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2006.