Much work has been done towards the hydrogenolysis of glycerol to 1,2-PDO and 1,3-PDO using various heterogeneous systems including Rh, Ru, Pt, PtRu, copper systems and Raney Ni in batch systems. However, routes to lower alcohols, such as 1-propanol and ethanol have been less discussed. From an industry point of view, the production of lower alcohols, such as propanol and ethanol, is very interesting. Different ruthenium, palladium and platinum catalysts were employed to study the effect of the support on the catalytic performance in batch mode. These catalysts were evaluated for their production of lower alcohols, especially 1-propanol using concentrated glycerol solutions. Among the other solid acids tested in combination with Ru/C, Amberlyst DT gave the most promising results from a 1-PO point of view, achieving a 34.9 mol% glycerol conversion with a selectivity of 38 mol% selectivity to 1-propanol. Despite the low glycerol conversion (1.3 mol%), Pd/C gave a promising 1-PO selectivity (> 85 mol%). The use of supported Ni catalysts, an inexpensive system, towards the chemical transformation of glycerol to lower alcohols, has appeared less frequently in the literature. The activity of Ni supported catalysts on silica and alumina was studied for the transformation of glycerol to lower alcohols, primarily 1-propanol and ethanol in a fixed bed continuous flow reactor. Several characterisation techniques were performed on the fresh and used catalyst, such as BET, XRD, TPD, TPR, TGA and electron microscopy. The objective was also to continue the development of a more detailed mechanistic understanding of the formation of lower alcohols from glycerol. In an endeavour to understand the process better, the role of proposed intermediates, 1,2-propanediol, 1,3- propanediol, ethylene glycol and ethanol was investigated, as well as the influence of the hydrogen partial pressure. Under the reaction conditions employed, it was clear that the hydrogenolysis of C-C and C-O bonds of glycerol took place to a lesser extent when compared to dehydrogenation and dehydration which are seen as the dominating initial steps. Ethanol was produced in high selectivities with 1,2-propanediol as feed and 1-propanol was the main product obtained when 1,3-propanediol was used as feed. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.

The influence of the form of the ZSM-5 zeolite, vanadium content and the elimination of the exterior surface acidity on the activity and selectivity of n-hexane oxidation was studied using a fixed bed reactor. Blank reactor studies (carborundum packed reactor) showed no conversion below 450°C with the highest conversion (8%) at 500°C. The dominant products were found to be carbon oxides (Sel./% = 90) with minor selectivities to the hexene isomers (7%) and the remainder being cracked products, THF and benzene. H-ZSM-5 with different SiO2/Al2O3 ratios (100 and 320) and Na-ZSM-5 (SiO2/Al2O3 ratio of 100) were tested under non-oxidative and oxidative conditions. Under oxidative conditions as the ratio of the SiO2/Al2O3 increased, the aluminium content decreased and so too did the cracking ability of the zeolite (i.e. yield of cracked products dropped from 36% to 8%). However, the use of the Na- form of ZSM-5 completely eliminated acid cracking. Under oxidative conditions H-ZSM-5 (100) was found to be more active and resulted in higher formation of cyclic and aromatic compounds. With increasing time on-stream and higher temperatures the catalyst was found to deactivate. Evidence of this was seen by a decrease in surface area and pore volumes of the spent catalyst. The Na-ZSM-5 (100) showed lower activity, but deactivation was shown to be lower. These findings led to the investigation of vanadium ion-exchanged Na-ZSM-5 catalyst for n-hexane activation. Catalysts with different vanadium loadings were prepared using the solid state ion-exchange method. Catalysts were characterised using various methods. These techniques showed that vanadium was successful loaded onto the catalyst and that the highest vanadium loading that could be achieved was 2.5%. The lower loadings were not found to alter the catalyst structure while the highest loading of 2.5% was found to show some pore blockage and to possibly alter the structural environment of the zeolite. Time on stream experiments were conducted and temperature (350, 400 and 450°C), contact time (0.5, 0.8, 1.1 and 1.5 s) and fuel-air ratios (0.7, 1.3 and 2) were varied. The optimum conditions (Conv./% = 39) for terminally activated products were found using the Na-V-ZSM-5 (0.9%) at a temperature of 400°C, a contact time of 1.1 s and fuel-air ratio of 1.3. With the lower fuel-air ratio of 0.7 (oxygen rich conditions), hexanal formation was favoured. The Na-V-ZSM-5 catalyst could be regenerated with initial activity and selectivity being regained. Silanisation was found to be possible, however, the extent and degree of silanisation was difficult to control. Pore blockage was possibly responsible for the lower activity and selectivity obtained using the silanised Na-V-ZSM-5. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.

The alkylation of 2-methylcyclohexanone imines using methyl acrylate has been investigated with a view to optimising the reaction conditions. The mechanism of this alkylation reaction has been investigated and it has been shown that the alkylation does not proceed via a 2,6-intermediate which subsequently undergoes a rearrangement to the 2,2-product, but rather proceeds directly to the 2,2-product. As it had been shown that the alkylation of 2-substituted cyclohexanone imines in dry methanol occurred at the more substituted position, it was decided, in the light of certain apparently anomolous patent work, to investigate the alkylation of unsubstituted cyclohexanone imines using a variety of electrophilic alkenes. The results show that in certain instances, 2,2-bis-alkylation occurs and in others, mono-alkylation and that it is the strength of the electron-withdrawing group attached to the alkene which determines whether 2,2-bis-alkylation occurs or not. The reasons for this are discussed in the text. The preparation of a number of novel 2,2-bis-eyclohexanones and an octahydroquinoline are described. The reaction of I-phenyl-2-propen-l-one (phenyl vinyl ketone) with the benzylaluine imines of 2-butanone and I-phenyl-2-propanone in methanol gave gave two novel bicyclic diones, whereas the reaction between the benzylamine imine of 3-pentanone with I-phenyl-2-propen-l-one gave only mono-eyclic products only even though there appeared to be no impediment to the formation of the bicyclic compound. The structures were determined using nuclear magnetic resonance and confirmed by X-ray crystallography. The reaction between I-phenyl-2-propen-l-one and N-(l-phenyl-l-ethylidene)benzylamine gave after hydrolysis only the mono-substituted product, 1,5-diphenyl-l ,5-pentandione. / Thesis (Ph.D.)-University of Natal, Durban, 1990.

Reaction of the pyrrolidine dienamines of ~1,8a-2-octalones with methyl vinyl ketone is complex. In methanol as solvent, the reaction occurs primarily with the linear dienamine isomer and results in annulation of the 8,8a-positions and, to a lesser extent, the 1,2-positions to give the corresponding octahydro-1 Hbenzo[d]naphthalene-2,10(3H,111-1)-dione and 3,4,5,6,7,8,8a,9-ctahydrophenanthren-2(10H)-one respectively. In toluene the dienamines react mainly in their cross-conjugated form. Diels-Alder addition of methyl vinyl ketone occurs across the 3,8a-positions to give the corresponding 9-acetylperhydro-2,4aethanonaphthalen-3-one and annulation of the 2,3-positions gives the 4,4a,5,5a,6,7,8,9-octahydroanthracen-2(3H)-one. The reaction of methyl vinyl ketone with the pyrrolidine dienamine of 4amethyl- 5-oxo-~ 1,8a-2-octalone is reported to give the aromatic product 3a, 7dimethyl- 2,3,3a,4,5,6-hexahydrophenalen-3,6-dionearisingfromp,o-annulation and in a related investigation with dienamines derived from isophorone it was reported that only products of Stork alkylation and Diels-Alder cycloaddition were isolated, there being no evidence for the reaction of methyl vinyl ketone with either the endo- or exocyclic o-positions of the dienamines. In an attempt to ascertain the reason for the apparently random changes in the regioselectivity of these related reactions some of this work was repeated and the reaction of methyl vinyl ketone applied to two other dienamines derived from 5,6,7,7a-tetrahydroindan-5-one and 4a,6-dimethyl-5-oxo-~1,8a-2-octalone. The reactions proved to be more complex than reported and several additional products have been isolated. Finally, reaction of phenyl vinyl ketone with dienamines derived from a1,8a_2-octalone was investigated. With the exception of the reaction of the 4amethyl dienamine, the main products isolated were those arising from addition of p.henyl vinyl ketone across the 3,8a-position to give the corresponding 9-benzoylperhydro-,4a-ethanonaphthalen-3-one. Reaction of the 4a-methyl dienamine with two equivalents of phenyl vinyl ketone gave a product tentatively assigned as the octahydrophenalenone. The mechanism of formation and spectral properties of the various products are discussed. / Thesis (Ph.D.)-University of Natal, 1991.

The high temperature transformations of trialkylboranes were investigated in the range: 50- 200 ºC. The extent of dealkylation was found to be linked to temperature with ca. 10% octene liberation from tri-n-octylborane at 150 ºC in the absence of bulk solvent. Analysis of the oxidised samples from the dealkylation investigation shows that, whereas the control experiment shows no back-isomerisation of tri-n-octylborane at 150 ºC, the addition of 10 mol% of DMF, DMSO, HMPA and trimethoxyphosphate results in back-isomerisation of the alkyl chain. In general, the addition of Lewis base catalyst was found to enhance the extent of dealkylation. In a supporting 11B NMR spectroscopy study to understand the interaction of trialkylboranes and Lewis bases, the interactions of a series of oxygen and phosphorous donor Lewis bases with tri-n-butylborane were found to be favourable, as indicated by large negative binding enthalpy ( HBIND) and entropy ( SBIND) values. Only the trialkylamine Lewis bases were found to have unfavourable interactions with tri-nbutylborane, as indicated by positive HBIND and SBIND values. The results also show that the chemical shift of the adduct at infinite dilution ( 11 B = ) is not as reliable a measure of the interaction between the two species and that correlation of binding constant (logKBIND) at 25.0 ºC to GBIND defines a linear trend that orders the Lewis bases according to spontaneity of the interaction with the strength of the dative bond formed. The applicability of 11B NMR spectroscopy to the study of the reactions of boranes and alkylboranes was extended to the investigation of the reduction of nitriles by BH3.SMe2 in dichloromethane (15-30 ºC). Results from the kinetic study indicate that the overall reduction with BH3.SMe2 is associative ( Sactivation = -71 ± 10 J K-1 mol-1), with the dependence of kobs data on SMe2 concentration highlighting the importance of the dissociation of the SMe2 from BH3 to the reduction process. The lack of reaction with propionitrile and benzonitrile at 25 ºC can be attributed to lack of stability of their adducts with BH3 as demonstrated by the small equilibrium constants for the formation of their adducts with borane; as determined by 1H NMR spectroscopy and further illustrated by computational calculation of their energies at the B3LYP/6-31G* level of theory. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

Chiral monoterpenes such as camphor have been widely used in the development of asymmetric catalysts with varying degrees of success. Pyridyl N-donor ligands derived from camphor have been extensively studied and have proven to be very successful. C3 pendant pyridyl alcohol ligands have been neglected until this study. Herein the synthesis of a series of six novel C3 pendant ligands is described. The ligands were synthesised in six steps (seven for ligand 4) using R-(+)-camphor as the starting material. Two alternative methods for the synthesis were investigated with the second method (Method B) proving to be superior. Several difficulties with regards to regioisomers and diastereomers were overcome in establishing the procedure for the synthesis of the ligands. The final compounds were successfully synthesised in moderate yields with absolute regio- and stereo-control. The ligands were evaluated as chiral catalysts in a series of different reactions. The first of these was the alkylation of a series of aldehydes using diethylzinc. This reaction was investigated in order to compare the efficacy of the novel compounds to previous camphor derived pyridyl alcohol ligands. All previous molecules of this type have been evaluated as catalysts in this reaction with varying degrees of success. The novel ligands successfully catalysed this reaction with moderate to good enantioselectivity (up to 85% ee). The results obtained showed these compounds to be significantly superior to a previous analogous C2 pendant β-amino alcohol reported in literature. The results were also comparable to other camphor derived pyridyl alcohol ligands reported previously. The synthesis of ligands 1-4 as well as their evaluation as catalysts in the alkylation of aldehydes with diethylzinc is discussed in detail in chapter 2 (Paper 1). The second reaction in which the ligands were evaluated was the Henry (Nitroaldol) reaction. This reaction has not seen many camphor derived ligands applied as catalysts. Two additional derivatives (5-6) were synthesized and all the compounds were screened as catalysts in this reaction. The ligands successfully catalyzed the reaction with good to excellent yields but only moderate selectivity (up to 56% ee). The details of this evaluation are discussed in chapter 3 (Paper 2). The final reaction in which the ligands were evaluated was the Diels-Alder reaction of 2- acrolyloxazolidinone with cyclopentadiene. The reaction was again successfully catalysed in moderate to good yields with good endo:exo selectivity but fairly poor stereoselectivity (up to 43% ee). Computational models of the proposed complexes were developed in order to explain the poor observed selectivity. The details of this study are reported in chapter 4 (Paper 3). Chapter 5 (Paper 4) involves a NMR and computational investigation of some of the ligands. Complete NMR elucidation using 2D NMR techniques were carried out for the selected ligands. Optimisation of the ligands using high level DFT calculations was carried out in order to aid in the visualisation of potential through space interactions within each molecule. / Thesis (Ph.D.)-University of KwaZulu-Natal, 2009.

The objectives of this project were to investigate the application of new methodologies for the preparation of benzyltetrahydroisoquinoline monomers and secondly, to synthesise the bisbenzyltetrahydroisoquinoline neferine and its analogues. Neferine was isolated from the roots of Nelumbo nucifera. This compound has been reported to exhibit important biological activities, which include anti-arrhymia, anti-platelet aggregation, anti-thrombosis, anti-cancer as well as anti-HIV activities. Moreover, neferine showed lower cytotoxicity compared to other isoquinolines. However, the total synthesis of this compound has not been reported. Two methodolologies based on the intramolecular hydroamination of aminostilbenes and aminoalkynes were investigated for the preparation of benzyltetrahydroisoquinolines with different oxygenation patterns. In these strategies, the aminostilbene and aminoalkyne precursors were successfully synthesised by the Heck and Sonogashira coupling reactions, respectively. The attempts to cyclise the aminostilbenes into the corresponding tetrahydroisoquinolines under base-catalysed, metal-catalysed and acid-catalysed conditions were unsuccessful. On the other hand, cyclisation of aminoalkynes into dihydroisoquinolines was achieved with the aid of titanium catalysts. Different titanium catalysts were tested for this hydroaminationation reaction. Optimum results were obtained with bis-(cyclopentadienyl)dimethyl titanium(IV) catalyst, albeit the yields were inconsistent when the reaction was performed on a larger scale. Induction of the desired stereochemistry on the dihydroisoquinolines prepared by the hydroamination of aminoalkynes was attempted with the chiral BINOL phosphoric acid catalyst without success. The catalyst was prepared in good yields and high enantiomeric excess from cheap and readily-available starting materials. Had this reaction been successful, this would have been a breakthrough in the stereoselective reduction of dihydroisoquinolines as most chiral catalysts, which are currently employed are expensive, difficult to prepare and some are air and moisture-sensitive. Although the first objectives of this project are not fully met, the results obtained in the synthesis of benzyltetrahydroisoquinolines by the hydroamination of aminostilbenes and aminoalkynes contribute greatly to the prevailing literature on the synthesis of benzyltetrahydroisoquinolines by these reactions. Presently, there is limited literature on the synthesis of benzyltetrahydroisoquinolines by these methods. Moreover, there is a need for the development of new synthetic strategies that would render benzyltetrahydroisoquinolines in minimum steps and good yields. It was planned that, upon successful synthesis of benzyltetrahydroisoquinolines from aminostilbene and aminoalkyne precursors, these modern methodologies would be applied in the synthesis of the two benzyltetrahydroisoquinoline scaffolds of neferine. However, these routes could not be pursued due to failure to ringclose the aminostilbenes and irreproducibility of results in the preparation of dihydroisoquinolines from aminoalkynes. Therefore, classical procedures were employed for the preparation of benzylisoquinoline nuclei of neferine. Three different synthetic routes were followed for the synthesis of neferine and its analogues. The first two methods were based on the Ullmann coupling reaction for the formation of the diaryl ether bond. The first method entailed an early construction of the ether link and late construction of the two isoquinoline rings on the ether bridge. The second method involved synthesis of the two isoquinoline nuclei, and coupling of the two units by the Ullmann reaction in the late stages of the synthesis. In the last synthetic strategy, the diaryl ether bridge was constructed by the nucleophilic aromatic substitution reaction. In all the three methods, the two isoquinoline rings were formed by the Bischler-Napieralski cyclisation reaction. In the first route, we succeeded in preparing the two major building blocks, which were N-(3,4-dimethoxyphenylethyl)-4-benzyloxy-3-iodophenylacetamide and [2- (4’-hydroxy-3’-methoxyphenyl)ethyl]carbamic acid tert-butyl ester. The Ullmann coupling of the two compounds afforded the diphenyl ether N-(3,4- dimethoxyphenylethyl)-4-benzyloxy-3-(4-(3-methoxyphenoxy)ethyl-tertbutylcarbamate) phenylacetamide, albeit in low yields. Although N-(3,4- dimethoxyphenylethyl)-4-benzyloxy-3-(4-(3-methoxyphenoxy)ethyl-tertbutylcarbamate) phenylacetamide was obtained in low yields, the successful formation of the diaryl ether bond from electron-rich haloacetamide and hydroxyphenethylamine is a great advancement in the synthesis of bisbenzyltetrahydroisoquinolines. In the second approach, the two benzyltetrahydroisoquinoline precursors for the Ullmann coupling reaction were successfully synthesised. These were the 7-hydroxybenzyltetrahydroisoquinoline and the 3’-iodobenzyltetrahydroisoquinoline. The Ullmann coupling reaction of the two isoquinolines did not give any fruitful results. In the last synthetic strategy, the formation of the diaryl ether bridge was based on the nucleophilic aromatic substitution reaction. In this route, we managed to synthesise the two coupling partners for the nucleophilic aromatic substitution reaction leading to Omethylneferine. One of the building blocks was the natural benzyltetrahydroisoquinoline, hydroxylaudanidine, and its coupling partner was N- [2-(4-fluoro-3-nitrophenyl)ethyl]-2-(4-methoxyphenyl)-N-methylacetamide. The major challenges in this route were encountered in the preparation the fluoroacetamide, which involved several low-yielding synthetic steps and tedious chromatographic purifications. The nucleophilic aromatic substitution reaction of the two precursors was attempted in vain. Even though the total synthesis of neferine could not be accomplished, it is strongly believed that the developed synthetic routes will enable us to complete the synthesis of the targeted compound and other naturally-occurring bisbenzyltetrahydroisoquinolines. The results obtained herein represent a significant advance considering the importance of the bisbenzyltetrahydroisoquinolines as biologically active compounds. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

African traditional medicine relies largely on the abundant African flora estimated at several tens of thousands of species. These plants, like other living organisms, produce natural products which are organic molecules exhibiting a remarkable wide range of chemical diversity and a multiplicity of biological properties. Over the past 20 years, interest in drugs of plants origin has been reviving and growing steadily. Among the broad spectrum of natural products that are showing promise as possible leads to useful therapeutic agents are the terpenoids. In the present study, selected African medicinal plants were investigated for the presence of extractable and exploitable terpenoids as leads or raw materials for producing more potent bioactive compounds for pre-clinical drugs discovery programme for chemoprotective agents against cancer, HIV/AIDS, diabetes, hypertension, malaria and other chronic diseases. The plants investigated in this study included Callistemon salignus, C. viminalis, Melaleuca bracteata var. revolution gold, M. bracteata var. revolution green, M. trichostachya var. compata, Syzygium aromaticum and Tectona grandis. These plants were subjected to two separate regimes of phytochemical extraction protocols namely volatile and non-volatile-extraction protocol. The Callistemon species and Melaleuca species upon hydrodistillation afforded essential oils. The gas chromatographic and mass spectrometric (GC-MS) analysis of these essential oils reveals that 1,8-cineole was the major constituent of the Callistemon oils. Similarly, 1,8-cineole was the major constituents of the essential oil of M. trichostachya var. compata, while methyl eugenol was the predominant constituent of the oils of Melaleuca bracteata var. revolution gold, and M. bracteata var. revolution green. Antibacterial investigation of the essential oils showed that they possess strong to moderate inhibitory effect against selected bacteria. In the non-volatile extraction protocol, various parts of the plants were sequentially extracted with organic solvents to obtain crude extracts which were subjected to fractionation and purification protocols (chromatographic techniques and re-crystallization). The crude extracts from the leaves of the Callistemon and Melaleuca species gave a crystalline mixture of betulinic acid and oleanolic acid in an appreciable yield. The crude extract from the cloves of Syzygium aromaticum yielded oleanolic acid as the major extractive and maslinic acid as minor extractive. The crude extracts from Tectona grandis afforded betulinic acid in an appreciable yield. The elucidation of the structures of the pure extractives was achieved by extensive 1D and 2D nuclear magnetic resonance (NMR) spectroscopy as well as infra-red spectroscopy (FT-IR) and mass spectrometry (MS). Betulinic acid and oleanolic acid were chosen as seed molecules for making known and unknown derivatives for lead optimization study. The semi-synthesized compounds were 3- acetoxyoleanolic acid, 3-acetoxyoleanolic hydrazide, 3-acetoxyloleanolic hydrazone, 3-succinyl oleanolic acid, 3-acetoxybetulinic acid, 3-succinylbetulinic acid and maslinic acid di-acetate. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2010.

Solar ultraviolet radiation is known to have deleterious effects on human skin and is a major cause of skin cancer. Therefore, the topical application of sunscreen preparations has gained wide usage for skin protection. These preparations typically contain a variety of chemical absorbers that absorb ultraviolet (UV) radiation and physical blockers that scatter, absorb and reflect UV light. The efficacy of sunscreens can be estimated by the Sun Protection Factor (SPF) which depends on the UV filters present in the formulations. However, although some of these commercial sunscreens have beneficial effects, they can also have undesirable results. It is known that the sunscreens undergo electronic excitation when exposed to UV light which may make them susceptible to photochemical modification. The production of reactive intermediates (e.g. free radicals) and stable photoproducts, either due to photoisomerisation or photofragmentation is a major concern because these species may be toxic and may lead to a reduction in efficacy. Hence a study of the photochemistry of these chemical absorbers found in commercial sunscreens is of great importance. Photostability and broad-spectrum studies of some Australian commercial sunscreen products were undertaken by means of spectrophotometric and chromatographic methods. The sunscreen products dissolved in methanol solutions were irradiated using simulated solar radiation. High performance liquid chromatography (HPLC) was used to identify and quantify the active chemical ingredients. UV spectrophotometry was used to monitor the spectral absorbance before and after UV exposure of the formulations. Our results show that some of the evaluated photoactive chemical absorbers currently used in sunscreens are unstable upon UV radiation. This was mainly due to either photoisomerisation and/or photofragmentation of some active chemical ingredients. An examination of the photochemistry of 2-ethylhexyl-p-methoxycinnamate (2- EHMC), an ultraviolet B absorber that was found in all the suncare products investigated in this study was undertaken. Irradiation of dilute (~ 10-6 M) solutions of EHMC with wavelengths of light greater than 300 nm results in trans - cis photoisomerisation leading to a photostationary equilibrium mixture. However, pure or concentrated solutions of 2-EHMC upon prolonged irradiation showed additional photoproducts. These were isolated by preparative high performance liquid chromatography (HPLC) and characterised by nuclear magnetic resonance (1H NMR) spectroscopy, which was used to identify them as [2 +2] cycloadducts of 2-EHMC. There are 13 possible dimers formed via a [2+2] cycloaddition reaction mechanism across the ethylenic double bond, however only the stable and energetically favoured isomers were isolated. In addition, ab initio molecular orbital calculations have been used to investigate the structures and the transition states of the various dimers resulting from the cycloaddition reactions. Geometry optimizations and energy calculations were performed with the Gaussian 98 program, using the B3LYP density functional and 6-31+G (d) basis set. GaussView was used to visualize the transition state structures. The theoretical calculations predicted the most stable dimer forms. The trans-trans configuration at the cyclobutane ring of the 2-EHMC adduct gave relatively more stable photoproducts. The theoretical results have been confirmed by HPLC isolation experiments, which together with the UV spectra of the different products; verify the presence of the different conformers of 2-EHMC. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2009.

Nickel molybdenum oxide catalysts with different chemical compositions have been synthesized and tested for the oxidative dehydrogenation of n-hexane. The co-precipitation method was used for the synthesis and several methods were used to characterize these catalysts. These include inductively-coupled plasma optical emission spectroscopy, Raman spectroscopy, infrared spectroscopy, energy dispersive X-ray spectroscopy, scanning electron microscopy, temperature programmed reduction, temperature programmed desorption, X-ray photo-electron spectroscopy and X-ray diffraction spectroscopy techniques as well as the Brauner-Emmet-Teller technique for surface area determination. The phase composition of the catalysts was largely dependent on the chemical composition. Catalyst testing on n-hexane feed was done with a fixed bed continuous flow reactor and experiments were performed with feed/air ratios above and below the flammability limit. Varied reaction conditions were used for the catalytic testing. Prior to the catalytic testing, blank experiments were performed. Analysis of the products were done both online and offline in conjunction with gas chromatography employing FID and TCD detectors. The influence of the catalyst on the conversion of n-hexane and selectivity to dehydrogenation products is reported. Products observed were the carbon oxides (CO and CO2), isomers of hexene (1-hexene, 2-hexene and 3-hexene), cyclic C6 products (cyclohexene and benzene), cracked products: alkanes/alkenes (propane/ene, butane/ene) and oxygenates (ethanal, acetic acid and propanoic acid). B-NiMoO4 was most selective to the hexenes, especially, 1-hexene and a reaction scheme is proposed. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2009.