Browsing by Author "Titinchi, Salam"
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Item 4-(Dimethylamino)pyridinium chlorosulfonate: A new ionic liquid exhibiting chlorosulfonic acid action as monoprotic Brönsted acid and no sulfonating reagent(Journal of Molecular Liquids, 2021) Titinchi, SalamMany papers considered chlorosulfonic acid as a sulfonating and sulfating agent, whereas our previous work and a few reports showed it acts as a monoprotic Brönsted acid. Therefore, in the present work, we decided to respond to this question by investigating the reaction between chlorosulfonic acid and DMAP. First, a new ionic liquid viz. 4-dimethylaminopyridinium chlorosulfonate was obtained, which its chemical structure was elucidated using different spectroscopic techniques. Another derivative, 4-dimethylaminopyridinium hydrogen sulfate, was also synthesized, which showed a similar NMR pattern. The NMR spectra analyses of reactants, the new ionic liquid, and 4 dimethylaminopyridinium hydrogen sulfate support the formation of 4-dimethylaminopyridinium chlorosulfonate. Therefore, the formation of N-sulfonic acid-4-dimethylaminopyridinium chloride or 4-dimethylaminopyridinium sulfate and the presence of an excess of chlorosulfonic acid and sulfuric acid were ruled out based on the spectroscopic results. Finally, the new ionic liquid's thermal behavior and thermal stability were investigated, and a possible mechanism was presented for its degradation based on a TGA/DTA analysis.Item Coordination polymers as heterogeneous catalysts for oxidation reactions(University of the Western Cape, 2014) Alarbi, Zohra; Titinchi, Salam; Abbo, HannaThis study describes the synthesis and characterisation of coordination polymers complexes of Cu(II) and VO(IV) with two polymeric ligands N,Nʹ -1,2-phenylene bis(5-methylenesalicylidenamine)(L1) and N,Nʹ -1,4-butylene bis(5 methylenesalicylidenamine) (L2). Ligands L1 and L2 formed by condensation of 5,5ʹ-methylene bis-(salicylaldehyde) with 1,2-phenylenediamine and 1,4-diaminobutane respectively. The ligands and the complexes were characterized by UV/Vis spectroscopy, proton and carbon nuclear magnetic resonance spectroscopy (1H and 13C-NMR), Fourier transform infrared spectroscopy (FTIR), high resolution scanning electron microscopy (SEM) and thermogravimetric Analysis (TGA)Item Geochemical evaluation of source rock potential and characterization of hydrocarbon occurrences in the Eastern Dahomey Basin, Nigeria(University of Western Cape, 2020) Mohammed, Saeed; Opuwari, Mimonitu; Titinchi, SalamNigeria is endowed with significant oil sand and heavy oil reserves. These reserves are found within the Cretaceous Afowo Formation in the Eastern Dahomey Basin. The petroleum systems and quality of these reserves are poorly understood. Harnessing these resources necessitate comprehensive deposit evaluation and characterization.Item Graphene based materials for carbon capture(University of Western Cape, 2020) Kelly, Gabrielle Enid; Titinchi, Salam; Abbo, HannaThe adverse effects of CO2 and greenhouse gas emissions into the atmosphere is believed to be one of the causes of climate change. The seriousness of global warming is encouraging the development of technologies designed to reduce CO2 emissions. Adsorption in the broadest context can be considered to be a promising method to address this due to the energy saving potential and regenerability, compared to other techniques. In this study, graphite was first oxidized to graphene oxide (GO) with concentrated acid. This was followed by formation of the aminosilanes viz. 3- aminopropyl-triethoxysilane (APTES), tris(2-aminoethyl)amine (TRIS) and guanidine being functionalized onto the surface of graphene oxide (GO). A second series involving the ordered mesoporous materials (OMS) was prepared employing cetyltrimethylammonium bromide (CTAB) and P123 triblock copolymer, as the structure directing agents for the organization of polymerizing silica species. Following the self-assembly of OMS onto GO, the so formed GO-OMS compound was modified with polyethylenimine (PEI). Several characterization techniques such as X-ray powder diffraction (XRD), Fourier Transform Infra-Red (FT-IR) spectroscopy, high resolution scanning microscopy (HRSEM), high resolution transmission electron microscopy (HRTEM) and N2 physisoprion employing the Brunauer-Emmett-Teller (BET) analysis to determine specific surface areas of porous solid materials were employed to study the structural, morphological and textural properties of the adsorbents.Item Graphene modified Salen ligands for the electrochemical determination of heavy metal ions(University of Western Cape, 2020) Naidoo, Fayyaadh; Titinchi, SalamEnvironmental pollution is a major threat to all life, which needs to be addressed. Heavy metals are well-known environmental pollutants due to their toxicity and, persistence in the environment toxicity for living organisms and having a bioaccumulative nature. Environmentally, the most common hazardous heavy metals are: Cr, Ni, Cu, Zn, Cd, Pb, Hg, and As. Remediation using conventional physical and chemical methods is uneconomical and generates waste chemicals in large quantities. This study focuses on the extraction and determination of heavy metals (Nickel, Copper and Cobalt) by chelating Schiff base ligands of the type [O,N,N,O] with these metal ions. Two Schiff base ligands [N,N’-ethylenebis(salicylimine)] (Salen) and ligand [1,3-bis(salicylideneamino)-2-propanol] (Sal-DAP) were synthesized and characterised using FTIR, 1H and 13C NMR spectrometry and GC-MS techniques. Electrochemical detection of heavy metal ions in this work was achieved via ligand-metal complexation via two approaches. The in-situ method in which the metal and ligands were added to the electrochemical cell and stirred to allow complexation to occur and monitored by square wave voltammetry. While the ex-situ approach involved modifying the electrode surface by depositing a thin film of Schiff base on the electrode surface and immersed into a heavy metal solution to allow the complexation. Three modified GCE were used viz. Salen coated GCE, reduced graphene oxide-Salen coated GCE and a nafion-Salen coated GCE. The two approaches used for the electrochemical detection were successful and effective. The ex-situ approach was selected for the modification of the electrode surface since it demonstrated a higher capacity for heavy metal ion extraction.Item Metal–metal correlation of biodegraded crude oil and associated economic crops from the Eastern Dahomey Basin, Nigeria(MDPI, 2022) Mohammed, Saeed; Opuwari, Mimonitu; Titinchi, SalamThe presence of heavy metals in plants from oil sand deposits may reflect mineralization resulting from petroleum biodegradation. Petroleum composition and heavy metal analyses were performed using thermal desorption gas chromatography and atomic absorption spectrophotometry on oil sand and plant root samples from the same localities in the Dahomey Basin. The results from the oil sand showed mainly heavy-end hydrocarbon components, humps of unresolved complex mixtures (UCM), absences of C6-C12 hydrocarbon chains, pristane, and phytane, indicating severe biodegradation. In addition, they showed varying concentrations of vanadium (2.699–7.708 ppm), nickel (4.005–11.716 ppm), chromium (1.686–5.733 ppm), cobalt (0.953–3.223 ppm), lead (0.649–0.978 ppm), and cadmium (0.188–0.461 ppm). Furthermore, these heavy metals were present in Citrus, Theobroma Cacao, Elaeis guineensis, and Cola.Item New protocols for the synthesis of 5-amino-7-(4-phenyl)-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate esters using an efficient additive(TUBITAK, 2020) Titinchi, Salam; Ghaffari Khaligh, Nader; Mihankhah, TaranehThis work introduces a new additive named 4,4’-trimethylenedipiperidine for the practical and ecofriendly preparation of ethyl 5-amino-7-(4-phenyl)-4,7-dihydro-[1,2,4]triazolo[1,5-a]pyrimidine-6-carboxylate derivatives. This chemical is commercially available and easy to handle. It also possesses a low melting point and a broad liquid range temperature, high thermal stability, and good solubility in water. Based on green chemistry principles, the reaction was performed in a) a mixture of green solvents i.e. water and ethanol (1:1 v/v) at reflux temperature, and b) the additive was liquefied at 65 ◦ C and the reaction was conducted in the liquid state of the additive. High yields of the desired triazolo-pyrimidines were obtained under both aforementioned conditions. Our results demonstrated that this additive, containing 2 Lewis base sites and able to act as an acceptor-donor hydrogen bonding group, is a novel and efficient alternative to piperidine, owing to its unique properties such as its reduced toxicity, nonflammable nature, nonvolatile state, broad liquid range temperature, high thermal stability, and ability to be safely handled. Furthermore, this additive could be completely recovered and exhibited high recyclability without any change in its chemical structure and no significant reduction in its activity.Item Novel nanostructure electrocatalysts for oxygen reduction and hydrogen evolution reactions(University of the Western Cape, 2020) Luo, Lin; Titinchi, SalamThe widespread use of fossil energy has been most convenient to the world, while they also cause environmental pollution and global warming. Therefore, it is necessary to develop clean and renewable energy sources, among which, hydrogen is considered to be the most ideal choice, which forms the foundation of the hydrogen energy economy, and the research on hydrogen production and fuel cells involved in its production and utilization are naturally a vital research endeavor in the world.Item Novel Nanostructure Electrocatalysts for Oxygen Reduction and Hydrogen Evolution Reactions(University of Western Cape, 2020) Lou, Lin; Titinchi, Salam; Abbo, Hannawidespread use of fossil energy has been most convenient to the world, while they also cause environmental pollution and global warming. Therefore, it is necessary to develop clean and renewable energy sources, among which, hydrogen is considered to be the most ideal choice, which forms the foundation of the hydrogen energy economy, and the research on hydrogen production and fuel cells involved in its production and utilization are naturally a vital research endeavor in the world. Electrocatalysts are one of the key materials for proton exchange member fuel cells (PEMFCs) and water splitting. The use of electrocatalysts can effectively reduce the reaction energy barriers and improve the energy conversion efficiency. This thesis mainly focuses on development novel nanostructure electrocatalysts with low-cost, high activity and good durability used for oxygen reduction reaction (ORR) and hydrogen evolution. (1) Nitrogen-doped PtNiMo ternary alloys were synthesized by impregnation reduction followed by annealing at high temperatures.Item Photocatalytic degradation of organic pollutants using Ag-Fe₃O₄/SiO₂/TiO₂ nanocomposite(University of the Western Cape, 2015) Noganta, Siyasanga; Titinchi, Salam; Abbo, HannaThe global lack of clean water for human sanitation and other purposes has become an emerging dilemma for human beings. The presence of organic pollutants in wastewater produced by textile industries, leather manufacturing and chemical industries is an alarming matter for a safe environment and human health. For the last decades, conventional methods have been applied for the purification of water but due to industrialization these methods fall short. Advanced oxidation processes and their reliable application in degradation of many contaminants have been reported as a potential method to reduce and/or alleviate this problem. Lately, it has been assumed that incorporation of some metal nanoparticles such as magnetite nanoparticles as photocatalyst for Fenton reaction could improve the degradation efficiency of contaminants. Core/shell nanoparticles, are extensively studied because of their wide applications in the biomedical, drug delivery, electronics fields and water treatment. The current study is centred on the synthesis of silver-doped Fe₃O₄/SiO₂/TiO₂ photocatalyst. Magnetically separable Fe₃O₄/SiO₂/TiO₂ composite with core–shell structure were synthesized by the deposition of uniform anatase TiO₂ NPs on Fe₃O₄/SiO₂ by using titanium butoxide (TBOT) as titanium source. Then, the silver is doped on TiO₂ layer by hydrothermal method. Integration of magnetic nanoparticles was suggested to avoid the post separation difficulties associated with the powder form of the TiO₂ catalyst, increase of the surface area and adsorption properties. Lastly and most importantly magnetic nanoparticles upsurge the production of hydroxyl groups or reduced charge recombination. The a synthesized catalysts were characterized using Transmission Electron Microscopy, X-ray Diffraction; Infra-red Spectroscopy, Scanning Electron Microscope and Energy Dispersive Spectroscopy. Other characterization techniques includeVibrating Sample Magnetometry, Brunauer Emmett Teller analysis and Thermogravimetric analysis. The average size of the particles size is 72 nm. Furthermore the photocatalytic performances of the magnetic catalysts were assessed in comparison with that commercial titanium dioxide for the degradation of methylene blue using photochemical reactor under ultra violet light. The results showed that the photocatalytic activity was enhanced using Fe₃O₄/SiO₂/TiO₂ and Ag-Fe₃O₄/SiO₂/TiO₂ compared with that for Fe₃O₄, commercial titanium dioxide powder.Item Porous metal complexes for CO2 capturing(University of the Western Cape, 2017) Ndamyabera, Christophe Adrien; Titinchi, SalamThe need in energy has resulted in the burning of fossil fuels at an increasingly high level. The consequence is a release of high volumes of carbon dioxide gas (CO2) in the atmosphere. This gas is a major greenhouse gas which causes global warming. There is therefore a great need to efficiently sequestrate this gas (CO2) for a sustainable economic development and environment. A new class of metal organic frameworks (MOFs) is a promising high potential application in carbon dioxide capture. In the current study, synthetic methods were developed for the design of porous cobalt succinates and nickel hydroxy-terephthalates for CO2 adsorption. The methods developed and interrogated include, sonication, hydrothermal synthesis (at room temperature, reflux and Parr reactor), and microwave synthesis. The conventional cobalt chloride hexahydrate was substituted by cobalt acetate for synthesis at room temperature. Cobalt acetate was used to replace cobalt chloride in the synthesis of cobalt succinate at room temperature and led to a new cobalt succinate complex (CoS-Ac). The complexe CoS-Ac differs from CoS synthesized from cobalt chloride hexahydrate. Synthesis of cobalt succinate via sonication (CoS-sn) was achieved in 45 min and the structure of the complex was different when synthesized via the hydrothermal route (under reflux) abbreviated CoS-th.Item Source rock evaluation of Afowo clay type from the Eastern Dahomey Basin, Nigeria: Insights from different measurements(Springer Nature, 2020) Mohammed, Saeed; Opuwari, Mimonitu; Titinchi, SalamThe Cretaceous Afowo Formation in the Eastern Dohamey Basin is characterized by an admixture of lithofacies ranging from sandstones, claystones, shales, clays, sand/shale, and sand/clay intercalations. The sandy facies, a mix of sandstone, clay, shale, and intercalations, contain biodegraded hydrocarbons while the shales and claystones that underlie it are rich in organic matter. The hydrocarbon-bearing interval is commonly referred to as the oil sand or tar sand. In this study, Afowo clay type underlying an outcrop of the oil sand was appraised for its hydrocarbon potential with loss on ignition, thermogravimetry, and rock evaluation pyrolysis.Item Supported catalysts for CO2 cycloaddition reactions(University of the Western Cape, 2022) Mba, Rigobert Axel Engo; Titinchi, SalamCarbon dioxide (CO2) is a major greenhouse gas (GHG) released into the environment due to increasing human activities. Cyclic carbonates on the other hand, are valuable compounds with several functions such as, polar aprotic solvent, and intermediate in chemical synthesis. The cycloaddition reaction of CO2 and epoxides was found to be a promising method for the synthesis of cyclic carbonates, because it uses CO2 as a feed stock, contributing to the reduction of CO2 in the environment.Item Supported metal catalysts for friedel-crafts alkylation(2013) Hlatywayo, Tapiwa; Titinchi, Salam; Petrik, LeslieThe research focused on the synthesis, characterisation and activity of zeolite supported metal catalysts for the Friedel-Crafts alkylation of benzene with t-butyl chloride. Alkyl benzenes are traditionally produced via systems that employ the use of Lewis acids or strong mineral acids. There have been widespread concerns over these approaches based on their environmental impacts and separation difficulties. Recent approaches have endeavoured the much to use more environmentally eco-friendly systems and zeolites have proved to be versatile support materials. The use of zeolites has also shown to greatly improve product selectivity as well as easing separation constraints. However the adoption of zeolites on large scale Friedel-Crafts alkylation has been hampered by the high cost of zeolite production from commercial sources. On the other hand fly ash has been found to be a viable starting material for zeolite synthesis. Apart from that South Africa is faced with fly disposal challenges and there is continual accumulation of fly ash at the coal fired power stations, which provide about 77 % of the power produced in the country. In this light the use of fly ash will help to reduce the disposal constraints as well as providing a cheap starting material for zeolite synthesis. In this study the hierarchical Zeolite X has been successfully synthesised from fly ash via a hydrothermal treatment. The zeolite was then loaded with Fe/Mn via two approaches namely liquid phase ion exchange and incipient wetness impregnation. For comparison purposes seasoned commercial support materials namely HBEA and MCM- 41 were also loaded with the same metals and characterised with various techniques namely; HRSEM, EDS, HRTEM, XRD, SAED, ICP-OES and N2 adsorption analysis, It was found from the characterisation undertaken that the integrity of the respective supports was generally retained upon metal loading. Both the ICP-OES and the EDS proved that the desired metals were successfully introduced onto the zeolitic support materials. The calculated percentage metal loading for the catalysts prepared via incipient wetness impregnation was closely related to the actual values obtained from the ICP-OES analysis for both the monometallic and the bimetallic catalysts (Fe/Mn). It was observed that the amount of metal that can be introduced on a zeolite via liquid phase ion exchange is largely dependent on the cation exchange capacity of the zeolite Supported metal catalysts for FC alkylation Page v and of the catalysts prepared using 0.25 M Fe solution it was found that Zeolite X had the highest Fe wt% loading of 11.4 %, with the lowest loading of 2.2 % obtained with the MCM-41 supported catalyst. The XRD patterns for the both HBEA and the MCM-41 supported metal catalysts resembled the patterns of the respective prestine support materials except in the case of catalysts with anFe wt % of more than 10, which exhibited peaks due to the Fe2O3 crystallites. In the case of the hierarchical Zeolite X, the metal loaded support had a significant reduction in the XRD peak intensities. The prepared catalysts were tested for the alkylation of benzene with t-butyl chloride. The benzene was also used as the solvent. The alkylation reaction was carried out in a round bottomed flask under reflux conditions and stirring at a temperature of 45 oC over a period of 5 h. A total of 18 catalysts was tested and the highest percentage conversion of 100 % was obtained with the 10%FeH after a reaction time of 2 h. The general trend obtained with the majority of the catalysts was characterised with a rapid initial increase and then steady state was achieved. Generally after a reaction time of 3 h almost all the catalysts had reached steady state in terms of the percentage conversion obtained. The outcomes reflect that the inclusion of Mn does not enhance the conversion but rather decreases it. It was also found that the Mn was not active in the alkylation of benzene as shown by the inactivity of the 10%MnM, where 10% by weight Mn was loaded on MCM-41. However the other monometallic catalysts containing Mn supported on Zeolite X and HBEA were found to be active. The activity is attributed to the presence of Brønsted acid sites in these zeolites which are not present in MCM-41. The selectivity studies reflect that the inclusion of Mn does slightly improve the selectivity towards the formation of the monoalkylated product (t-butyl benzene). The highest selectivity of 91.1 % was obtained with the 10%FeMnM after a reaction time of 4 h. MCM-41 supported catalysts had a relatively higher selectivity compared to the other supports. Considering the Fe monometallic catalysts tested it generally can be said that the yield were in the order HBEA > MCM-41 > Zeolite X. It however should be noted that the percentage yield is calculated from the conversion and selectivity percentages, this implies that the factors affecting these parameters will consequently affect the percentage yield obtained. Supported metal catalysts for FC alkylation Page vi The alkylation reaction was found to be characterised by the formation of two intermediate products which could not be identified. These products were formed during the transient start up stages of the reaction and would disappear from the reaction mixture with longer reaction times, and after 3 h in almost all the reactions studied the intermediates were not detected in the reaction mixture. The main products found were the monoalkylated product (desired product) and the para isomer (1,4-t-di-butyl benzene). There were no other dialkylated isomers or trialkylated products detected. The formation of the para isomer was usually after a reaction time of 2 h in most reactions. The research managed to show that the hierarchical Zeolites X can be synthesised from fly ash and ion exchange and incipient wetness impregnation are appropriate approaches that can be used to introduce Fe/Mn onto the support materials studied. The catalysts prepared were active to varying degrees in the Friedel-Crafts alkylation of benzene with t-butylchloride, with the exception of the 10%MnM which was found to be inactive.Item Synthesis and characterization of new adsorbents for CO2 capturing(University of the Western Cape, 2014) Piet, Marvin; Titinchi, Salam; Abbo, HannaCarbon dioxide emissions have become a major concern as they are one of the contributing factors to the “green-house” effect. Recently, much effort has been put into separating carbon dioxide (CO2) from flue gases linked to the combustion processes at fixed point sources. The development of solid sorbents for adsorption based on CO2 capture has attracted much attention. Ordered Mesoporous Silica (OMS) materials have recently attracted much attention as solid adsorbents for capturing CO2. OMS have been investigated for this purpose owing to their high pore volume, large surface area and ease of functionalizationIn this work we report on the synthesis of OMS viz. MCM-41 and SBA-15 along with amorphous silica as adsorbents for CO2 capture. MCM-41 was prepared with surfactants having different alkyl chain lengths (C14TABr, C16TABr and C18TABr) where TABr is trimethylammonium bromide. SBA-15 was prepared using a Triblock copolymer as a structure directing agent for the organization of polymerizing silica species. Commercial amorphous silica gel was used for comparative purposes. Initial characterization OMS with powder X-Ray diffraction (XRD) and small angle diffraction (SAXS) yielded diffraction patterns which may be associated with well-ordered structures of hexagonal mesoporous material. Ease of preparation for MCM-41 materials allowed for convenient scale- up, obtaining highly ordered mesoporous silica MCM-41 at room temperature. SBA-15 was also found to be scaled up with considerable ease through increasing the volume of the autoclave during hydrothermal treatment. Structural, morphological and textural properties of the adsorbents were characterized by N2 physisorption measurements, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). TEM confirmed the hexagonal structure; SEM showed that C14MCM-41 had spheroidal particle morphology whereas SBA-15 displayed rod-like structures. High surface areas of up to 1302, 1186, 1211 and 1024 m2/g for C14MCM-41, C16MCM-41, C18MCM-41 and SBA-15, respectively were obtained. The pore size of MCM-41 materials was increased from 2.6 nm for C14MCM-41 to 4.4 nm in diameter for C18MCM-41 using surfactants with different alkyl chain lengths. CO2 adsorption characteristics of OMS were studied using CO2-temperature programmed desorption (TPD). The results showed that C14MCM-41, C16MCM- 41, C18MCM-41 and SBA-15 desorbed 0.19, 0.16, 0.11 and 0.26 mmol/g respectively. The synthesized OMS were then further modified by grafting various amine moieties on their surfaces in order to increase their CO2 adsorptive capabilities. 3-(Aminopropyl)triethoxysilane (APS), N-[3-(trimethoxysilyl)propyl]ethylene- diamine (TPED), 3-chloropropyl)-trimethoxysilane (CPS), ethyl 2-bromopropanoate, tris(2-aminoethyl)amine (TREN) and guanidine. Several characterization techniques such as XRD, SAXS, HRTEM, HRSEM, TGA, Fourier Transform Infra-Red (FT-IR) spectroscopy, CO2 isotherms and CO2-TPD were used to analyze amine grafted solid sorbents for CO2 capture. The results revealed that the structural integrity of the amine modified sorbents was not compromised during the grafting process. The structural properties of the supports, such as surface area and pore size, nature of amine and the number of amine groups, affected the loading and CO2 adsorption capacity of chemically grafted sorbents. APS grafted amorphous silica gel adsorbed 0.67 mmol/g CO2, which proved to be the highest compared to C18MCM-41 and SBA-15 grafted with APS and TPED. C18MCM-41, SBA-15 and amorphous silica gel were also grafted with TREN and adsorbed 0.42, 0.51 and 0.27 mmol/g of CO2, respectively. A systematic study of guanidine grafted on C14MCM-41, C16MCM-41 and C18MCM-41 was investigated, for the first time, to the best of our knowledge. Structural properties like variation in pore size, proved to enhance the adsorption capacity of the adsorbent, coupled with the guanidine molecules grafted on MCM-41 materials. C18MCM-41-guanidine showed the highest CO2 uptake of the guanidine grafted MCM-41 materials, adsorbing 0.30 mmol/g. A novel synthetic route to TPED-TREN grafted C18MCM-41 and SBA-15, using ethyl 2-bromopropanoate as a linker, was investigated as a potential adsorbent for CO2 capture, for the first time. C18MCM-41-TPED-TREN and SBA-15-TPED-TREN CO2 adsorption capacity were found to be 0.14 and 0.14 mmol/g, respectively.Item Synthesis and evaluation of metformin derivatives for anti-diabetes(University of the Western Cape, 2022) Parker, Amina; Titinchi, SalamType 2 diabetes mellitus (T2DM) is a significant public health crisis and is placed amongst the top ten leading causes of death worldwide. Metformin is the first-line drug used to treat T2DM, which is mainly attributed to its potent insulin sensitising properties and relatively low cost and side effects compared to other anti-diabetic drugs. However, metformin is associated with side effects such as gastrointestinal intolerance and reduced activity over time, while its variable pharmacokinetics, pharmacodynamics and pharmacogenomics leads to reduced effectiveness in some patients. In recent years, organic chemistry has been used to synthesise structural analogues of existing drugs, with more potent activity and target specificity than the parent drugs.Item Synthesis of new biguanide derivatives as potential antidiabetic drugs(University of the Western Cape, 2022) Salubi, Christiana Abimbola; Titinchi, SalamThe main purpose of this study was to synthesize biguanide compounds with potential as antidiabetic drugs. All biguanide compounds possess antidiabetic properties by decreasing the blood glucose level. Hence, we embarked on the synthesis of a series of biguanides in a threestep reaction which involves synthesis of a Schiff base, reduction of the Schiff base to a secondary amine using sodium borohydride and lastly formation of substituted biguanide derivatives with amines (primary or secondary) and dicyandiamide.Item Synthesis, characterization and physicochemical properties of platinum naboparticles on ordered mesoporous carbon(University of the Western Cape, 2011) Saban, Waheed; Petrik, Leslie F.; Titinchi, Salam; Dept. of Chemistry; Faculty of ScienceIn this study SBA-15 mesoporous silica template was synthesized and used as a sacrificial template in the preparation of ordered mesoporous carbon material. A chemical vapour deposition (CVD) technique using LPG or alternatively sucrose, pyrolyzed upon a mesoporous Si matrix were used to produce nanostructured ordered mesoporous carbon (OMC) with graphitic character after removing the Si template. The sucrose method was found to be a suitable route for preparing OMC. The OMC was used as a conductive three dimensional porous support for depositing catalytic nanophase Pt metal. Deposition of Pt nanoparticles on OMC was accomplished using a CVD method with Pt(acac)2 as a precursor. The synthesized nano-composite materials were characterized by several techniques such as, HRTEM, HRSEM, EDS, XRD, BET, TGA, FT-IR and CV.Item Zeolite encapsulated metal complexes as heterogeneous catalysts for oxidation reactions(University of the Western Cape, 2012) Willingh, Gavin Von; Titinchi, SalamThis study describes the synthesis and characterisation of Cu(II) and V(IV) complexes of tri- and quadridentate ligands L1 and L2 formed by condensation of ethylenediamine with acetylacetonate in 1:1 and 1:2 molar ratio, respectively. Encapsulation of these metal complexes in the nanocage of zoilite-Y generates new heterogeneous catalysts. These catalysts were synthesized employing the flexible ligand method encapsulation technique.The structures of these encapsulated complexes were established on the basis of various physico-chemical and spectroscopic studies. The results indicated that the complexes did not hinder or modify the framework or structure of the zeolite, confirming successful immobilization of Schiff-bases through the voids of zeolite Y.These encapsulated complexes were screened as heterogeneous catalysts for various oxidation reactions such as such as phenol, benzene, styrene and cyclohexene using a green oxidant (H2O2).For comparison, the corresponding neat complexes were screened as potential homogeneous catalysts for these oxidation reactions. The results proved that the corresponding homogeneous systems described here represent an efficient and inexpensive method for oxidation of phenol, benzene, styrene and cyclohexene, having advantages over heterogeneous catalysis are its high activity and selectivity and short reaction times. Its major problem is its industrial application regarding principally the separation of the catalyst from the products.The size of the substrate has a significant effect on the conversion by encapsulated complexes such as in styrene oxidation. Therefore, it was established that steric effects of the substrates play a critical role in the poor reactive nature of the encapsulated complexes.In general, the percentage conversion decreased upon encapsulation of complexes in zeolite Y. All catalysts studied proved to be potential catalysts for the various oxidation reactions.It has been shown in this study that encapsulation can effectively improve product selectivity but requires a longer reaction time in most cases for maximum activity.Furthermore,oxovanadium complexes were more reactive than copper-based catalysts in all oxidation reactions tested in this study.A reaction mechanism study revealed that the activity of the encapsulated and neat complexes occurs through either formation of peroxovanadium (V) or hydroperoxidecopper(II) intermediate species.The studies in this thesis, therefore, conclude that the Cu(II) and V(IV) complexes encapsulated in Y-zeolite are active heterogeneous catalysts for the selective oxidation of various substrates. Encapsulation of the metal complexes in the super cages (-cages) of the zeolite matrix has the advantages of solid heterogeneous catalysts of easy separation and handling, ruggedness, thermostability, reusability (regeneration of the deactivated catalysts) as well as share many advantageous features of homogeneous catalysts.Item Zeolite encapsulated metal complexes as heterogeneous catalysts for oxidation reactions(University of the Western Cape, 2012) Willingh, Gavin Von; Titinchi, SalamThis study describes the synthesis and characterisation of Cu(II) and V(IV) complexes of tri- and quadridentate ligands L1 and L2 formed by condensation of ethylenediamine with acetylacetonate in 1:1 and 1:2 molar ratio, respectively. Encapsulation of these metal complexes in the nanocage of zoilite-Y generates new heterogeneous catalysts. These catalysts were synthesized employing the flexible ligand method encapsulation technique.The structures of these encapsulated complexes were established on the basis of various physico-chemical and spectroscopic studies. The results indicated that the complexes did not hinder or modify the framework or structure of the zeolite, confirming successful immobilization of Schiff-bases through the voids of zeolite Y.These encapsulated complexes were screened as heterogeneous catalysts for various oxidation reactions such as such as phenol, benzene, styrene and cyclohexene using a green oxidant (H2O2). For comparison, the corresponding neat complexes were screened as potential homogeneous catalysts for these oxidation reactions. The results proved that the corresponding homogeneous systems described here represent an efficient and inexpensive method for oxidation of phenol, benzene, styrene and cyclohexene, having advantages over heterogeneous catalysis are its high activity and selectivity and short reaction times. Its major problem is its industrial application regarding principally the separation of the catalyst from the products.The size of the substrate has a significant effect on the conversion by encapsulated complexes such as in styrene oxidation. Therefore, it was established that steric effects of the substrates play a critical role in the poor reactive nature of the encapsulated complexes.In general, the percentage conversion decreased upon encapsulation of complexes in zeolite Y. All catalysts studied proved to be potential catalysts for the various oxidation reactions.It has been shown in this study that encapsulation can effectively improve product selectivity but requires a longer reaction time in most cases for maximum activity. Furthermore, oxovanadium complexes were more reactive than copper-based catalysts in all oxidation reactions tested in this study.A reaction mechanism study revealed that the activity of the encapsulated and neat complexes occurs through either formation of peroxovanadium (V) or hydroperoxidecopper(II) intermediate species.The studies in this thesis, therefore, conclude that the Cu(II) and V(IV) complexes encapsulated in Y-zeolite are active heterogeneous catalysts for the selective oxidation of various substrates. Encapsulation of the metal complexes in the super cages (-cages) of the zeolite matrix has the advantages of solid heterogeneous catalysts of easy separation and handling, ruggedness, thermostability, reusability (regeneration of the deactivated catalysts) as well as share many advantageous features of homogeneous catalysts.