http://hdl.handle.net/10500/2738 2013-05-24T13:02:57Z 2013-05-24T13:02:57Z Oyeyiola, Felix Adetunji http://hdl.handle.net/10500/5842 2013-03-26T08:04:56Z 2011-11-01T00:00:00Z

Synthesis and transformation of the 2,6,8-triaryl-2,3-dihydroquinolin-4(1H)-ones Oyeyiola, Felix Adetunji The 2-aryl-2,3-dihydroquinolin-4(1H)-ones were prepared via acid-catalyzed cyclization of the corresponding 2-aminochalcones, which were in turn, prepared by base-promoted Claisen-Schmidt aldol condensation of 2-aminoacetophenone and benzaldehyde derivatives. The 2-aryl-6,8-dibromo-2,3-dihydroquinolin-4(1H)-ones were prepared by reacting 2-aryl-2,3-dihydroquinolin-4(1H)-ones with N-bromosuccinimide (NBS) in carbon tetrachloride-chloroform mixture at room temperature. The 2-aryl-6,8-dibromo-2,3-dihydroquinolin-4(1H)-ones were subjected to palladium-catalyzed Suzuki-Miyaura cross-coupling reaction with arylboronic acid using dichlorobis(triphenylphosphine)palladium(II)-tricycohexylphosphine as catalyst mixture and potassium carbonate as a base in dioxane-water under reflux to afford the corresponding novel 2,6,8-triaryl-2,3-dihydroquinolin-4(1H)-ones in a single-pot operation. The latter were subjected to thallium(III) p-tolylsulfonate in dimethoxyethane under reflux to yield the 2,6,8-triarylquinolin-4(1H)-ones. The 2,6,8-triaryl-2,3-dihydroquinolin-4(1H)-ones were treated with molecular iodine in refluxing methanol to afford the corresponding 2,6,8-triaryl-4-methoxyquinolines. All the new compounds were characterized using a combination of 1H NMR & 13C NMR spectroscopy, IR and mass spectroscopic techniques.

2011-11-01T00:00:00Z Baratta, Antonio http://hdl.handle.net/10500/5101 2013-03-26T09:38:25Z 2010-11-01T00:00:00Z

The application of experimental design to investigate the solvent matrix effects observed during the Determination of Rhodium (Rh) in organic media by Graphite Furnace Atomic Absorption Spectrometry (GFAAS) Baratta, Antonio In an industrial application a GFAAS method for monitoring the Rh concentration in process streams is being used. Matrix effects are known to exist with the application of this technique; in fact, it was observed that different solvents lead to different results. Therefore, standard additions have to be employed for quantitative determinations, resulting in high costs and long analysis times. In an attempt to understand these interfering effects, fractional factorial designs were proposed to determine whether any GFAAS parameter was responsible for, or related to, the matrix effects. Seven GFAAS parameters were investigated: final temperature, ramp time and hold time of the transitions step (from the dry step); final temperature, ramp time and hold time of the ashing/pyrolysis step; ramp time of the atomisation step. The results showed that the matrix effects were not related to any specific parameter. A complete factorial design was implemented to demonstrate the fundamental role of the atomisation temperature. SEM analysis showed that the surface of the graphite tubes might be affected in different ways by different solvents. A Principal Component Analysis demonstrated that the matrix effects may be related to the viscosity and melting point of the solvents and may be independent of their molar mass. To identify the origins of these effects, an investigation on the link between the tube surface-sample matrix interactions and the physical properties of the matrices is recommended. Since GFAAS parameters cannot compensate for the matrix effects, standard additions remain the preferred mode of operation as it accounts for the effects in-situ.

2010-11-01T00:00:00Z Lesenyeho, Lehlogonolo Godfrey http://hdl.handle.net/10500/3970 2013-05-10T09:11:39Z 2010-09-01T00:00:00Z

Palladium-catalyzed heteroannulation of 2-ARYL- 3-IODO-4-(Phenylamino)quinolines and 4-(N,N-allylphenylamino)-2-ARYL-3-iodoquinolines Lesenyeho, Lehlogonolo Godfrey The previously described 2-aryl-4-chloro-3-iodoquinolines were prepared following literature procedure and in turn converted to the corresponding hitherto unknown 2-aryl-3-iodo-4-(phenylamino)quinoline derivatives using aniline in refluxing ethanol. These 2-aryl-3-iodo-4-(phenylamino)quinolines were reacted with allybromide in ethanol at room temperature to afford 4-(N,N-allylphenylamino)-2-aryl-3-iodoquinoline derivatives. The 2-aryl-3-iodo-4-(phenylamino)quinoline and 4-(N,N-allylphenylamino)-2-aryl-3-iodoquinoline derivatives were subjected to metal-catalysed carbon-carbon bond formations. Palladium(0)-copper iodide catalysed Sonogashira cross-coupling of 2-aryl-3-iodo-4-(phenylamino)quinoline with terminal alkynes afforded series of 1,2,4-trisubstituted 1H-pyrrolo[3,2-c]quinolines in a single step operation. On the other hand, the 4-(N,N-allylphenylamino)-2-aryl-3-iodoquinoline derivatives were found to undergo palladium-catalysed intramolecular Heck reaction to yield the corresponding 1,3,4-trisubstituted 1H-pyrrolo[3,2-c]quinolines. All new compounds were characterized by using a combination of NMR (1H and 13C), IR, mass spectroscopic techniques as well as elemental analysis.

2010-09-01T00:00:00Z Mputumana, Nomfusi Augusta http://hdl.handle.net/10500/3927 2012-06-14T16:59:55Z 2010-06-01T00:00:00Z

Siloxyl and Hydroxyl functionalized polymers by atom transfer radical polymerization Mputumana, Nomfusi Augusta The syntheses of siloxyl and hydroxyl chain end functionalized polystyrene and poly(methyl methacrylate) by Atom Transfer Radical Polymerization (ATRP) were effected by the following methods: (a) α-Siloxyl functionalized polymers were prepared in quantitative yields via a one-pot ATRP synthesis method for the polymerization of styrene or methyl methacrylate using a new siloxyl functionalized initiator adduct, formed in situ by the reaction of (1-bromoethyl)benzene with 1-(4-t-butyldimethylsiloxyphenyl)-1- phenylethylene in the presence of CuBr/bpy or CuBr/PMDETA as catalysts in diphenyl ether at 90 -110 oC. The polymerizations proceeded via controlled living radical polymerization methods and α-siloxyl functionalized polymers with predictable number average molecular weights (Mn = 1.8 x 103 - 17.40 x 103 g/mol), narrow molecular weight distributions (Mw /Mn = 1.03 - 1.41) and regiospecificity of the functional groups were obtained in quantitative yields. Similarly, the one-pot ATRP synthesis method for the preparation of α-bis(siloxyl) functionalized polymers were effected by the initiation of styrene or methyl methacrylate polymerization with a new bis(siloxyl) functionalized initiator adduct, formed by the in situ reaction of 1,1-bis(4-t-butyldimethylsiloxylphenyl)- ethylene with (1-bromoethyl)benzene in the presence of CuBr/bpy or CuBr/ PMDETA as catalytic systems in diphenyl ether at 90 -110 oC. Each polymerization reaction proceeded via a controlled living fashion to afford quantitative yields of the corresponding α-bis(siloxyl) functionalized polymers with predictable number average molecular weights (Mn = 1.7 X 103 - 15.00 x 103 g/mol), narrow molecular weight distributions (Mw /Mn = 1.03 - 1.35) and good control of chain end functionality. The acid catalyzed hydrolysis of α-siloxyl and α-bis(siloxyl) chain end functionalized polymers afforded the corresponding α-hydroxyl and α-bis(hydroxyl) chain end functionalized polymers, respectively. Polymerization kinetic data was employed to determine the controlled/living character of each ATRP reaction leading to the formation of different siloxyl functionalized chain end functionalized polymers. Polymerization kinetic measurements show that the polymerization follows first order rate kinetics with respect to monomer consumption and the number average molecular weight increases with percentage monomer conversion, resulting in the formation of polymers with narrow molecular weight distributions. Thin layer chromatography (TLC), 1H and 13C Nuclear Magnetic Resonance Spectrometry (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Size Exclusion Chromatography (SEC), Gas Chromatography (GC) and non - aqueous titrations were used to determine the structures and purity of the siloxyl functionalized initiator precursors as well as the siloxyl and hydroxyl functionalized polymers.

2010-06-01T00:00:00Z