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The production of biodiesel from a butter factory effluent was the main focus of the study. The alkali transesterification reaction was used to produce the biodiesel. The effect of the temperature, alcohol to oil molar ratio, catalyst concentration and the reaction time was investigated to determine the optimal reaction conditions. The reaction temperature varied from 45 °C to 65 °C with a 5 °C increment. The alcohol to oil molar ratio varied from 3:1 to 8:1 with an increment of 1:1. The experiments with varying catalyst load were carried out at 0.8 wt%, 1.0 wt% and 1.2wt%. The reaction time was kept constant at 120 minutes, but samples of the reaction mixture were taken at 10 minute intervals. The optimal reaction conditions according to the results were 50 °C, 6:1 alcohol to oil molar ratio, 1.0 to 1.2 wt% catalyst loads and a reaction time of 60 to 90 minutes. The optimal temperature was also the maximum temperature since a further increase in temperature lowered the ester content. Increasing the alcohol to oil molar ratio above 6:1 had no effect on the ester content. The increase in catalyst load decreased the time needed for the reaction to reach equilibrium. The purification process was also investigated. The biodiesel was washed with water, Magnesol® DSOLTM and Purolite® PD-206. The Magnesol® D-SOLTM was the best method for lowering the water content and the acid value of the fuel. A Magnesol® D-SOLTM content of 1.0 wt% was mixed with the biodiesel for 30 minutes in order to lower the water content and the acid value to below the maximum limit. A kinetic model for the biodiesel reaction was developed. The model was based on the second order reversible reaction. The temperature range for the model is from 45 °C to 55 °C. The forward reaction was found to be exothermic with an endothermic reverse reaction. The activation energy for the exothermic forward reaction varied between 9.478 and 26.937 kJ/mol while the activation energy for the endothermic reverse reaction varied between 74.161 and 136.433 kJ/mol for the reactions with a catalyst load of 1.2 wt%. The biodiesel was tested according to the SANS 1935:2011 standard. The biodiesel did not meet all the requirements of the standard. The flash point, sulphur content, carbon residue, oxidation stability, free glycerol, total glycerol and cold filter plugging point did not meet the specification of SANS 1935:2011. The biodiesel should be blended with mineral diesel if it is to be used commercially. The butter factory effluent can be used as a feedstock for the production of biodiesel. / Thesis (MIng (Chemical Engineering))--North-West University, Potchefstroom Campus, 2013.

The production of biodiesel from a butter factory effluent was the main focus of the study. The alkali transesterification reaction was used to produce the biodiesel. The effect of the temperature, alcohol to oil molar ratio, catalyst concentration and the reaction time was investigated to determine the optimal reaction conditions. The reaction temperature varied from 45 °C to 65 °C with a 5 °C increment. The alcohol to oil molar ratio varied from 3:1 to 8:1 with an increment of 1:1. The experiments with varying catalyst load were carried out at 0.8 wt%, 1.0 wt% and 1.2wt%. The reaction time was kept constant at 120 minutes, but samples of the reaction mixture were taken at 10 minute intervals. The optimal reaction conditions according to the results were 50 °C, 6:1 alcohol to oil molar ratio, 1.0 to 1.2 wt% catalyst loads and a reaction time of 60 to 90 minutes. The optimal temperature was also the maximum temperature since a further increase in temperature lowered the ester content. Increasing the alcohol to oil molar ratio above 6:1 had no effect on the ester content. The increase in catalyst load decreased the time needed for the reaction to reach equilibrium. The purification process was also investigated. The biodiesel was washed with water, Magnesol® DSOLTM and Purolite® PD-206. The Magnesol® D-SOLTM was the best method for lowering the water content and the acid value of the fuel. A Magnesol® D-SOLTM content of 1.0 wt% was mixed with the biodiesel for 30 minutes in order to lower the water content and the acid value to below the maximum limit. A kinetic model for the biodiesel reaction was developed. The model was based on the second order reversible reaction. The temperature range for the model is from 45 °C to 55 °C. The forward reaction was found to be exothermic with an endothermic reverse reaction. The activation energy for the exothermic forward reaction varied between 9.478 and 26.937 kJ/mol while the activation energy for the endothermic reverse reaction varied between 74.161 and 136.433 kJ/mol for the reactions with a catalyst load of 1.2 wt%. The biodiesel was tested according to the SANS 1935:2011 standard. The biodiesel did not meet all the requirements of the standard. The flash point, sulphur content, carbon residue, oxidation stability, free glycerol, total glycerol and cold filter plugging point did not meet the specification of SANS 1935:2011. The biodiesel should be blended with mineral diesel if it is to be used commercially. The butter factory effluent can be used as a feedstock for the production of biodiesel. / Thesis (MIng (Chemical Engineering))--North-West University, Potchefstroom Campus, 2013.

Among the new hydrogen storage materials, ammonia borane (AB) appears to be the most promising one as it has high hydrogen content, high stability, and being environmentally benign. Dehydrogenation of AB can be achieved via hydrolysis, thermolysis or methanolysis. Methanolysis of AB eliminates some drawbacks of other dehydrogenation reactions of AB. The use of colloidal and supported particles as more active catalyst than their bulky counterparts for the hydrolysis of AB implies that reducing the particle size can cause an increase in the catalytic activity as the fraction of the surface atoms increases by decreasing the particle size. Similarly, transition metal nanoclusters can be utilized as catalyst for the methanolysis of AB as well. For this purpose transition metal nanoclusters need to be stabilized to a certain extent. Actually in the catalytic application of transition metal nanoclusters one of the most important problems is the aggregation of nanoclusters into bulk metal, despite of using the best stabilizers. In this regards, the use of metal nanoclusters as catalysts in systems with confined void spaces such as inside mesoporous and microporous solids appears to be an efficient way of preventing aggregation. In this dissertation we report for the first time the use of intrazeolite rhodium(0) nanoclusters as a catalyst in the methanolysis of ammonia borane. Rhodium(0) nanoclusters could be generated in zeolite-Y by a two-step procedure: (i) incorporation of rhodium(III) cations into the zeolite-Y by ion-exchange, (ii) reduction of rhodium(III) ions within the zeolite cages by sodium borohydride in aqueous solution, followed by filtration and dehydration by heating to 550 &deg / C under 10-4 Torr. Zeolite confined rhodium(0) nanoclusters are stable enough to be isolated as solid materials and characterized by ICP-OES, XRD, SEM, EDX, HRTEM, XPS and N2 adsorption-desorption technique. The zeolite confined rhodium(0) nanoclusters are isolable, bottleable, redispersible and reusable. They are active catalyst in the methanolysis of ammonia-borane even at low temperatures. They provide exceptional catalytic activity with an average value of TOF = 380 h-1 and unprecedented lifetime with 74300 turnovers in the methanolysis of ammonia-borane at 25 &plusmn / 0.1 &deg / C. The work reported here also includes the full experimental details of previously unavailable kinetic data to determine the rate law, and activation parameters (Ea, &amp / #916 / H&amp / #8800 / and &amp / #916 / S&amp / #8800 / ) for the catalytic methanolysis of ammonia-borane.

More attention has been paid to find new type renewable energy sources because of increasing concern about the environmental problems arising from the combustion of fossil fuels as energy sources. The development of new storage materials will facilitate the use of hydrogen as a major energy carrier. Several possibilities exist for &lsquo / &lsquo / solid-state&rsquo / &rsquo / storage: the hydrogen can be trapped in metal organic frameworks, carbon nanotubes and certain alloys / or one can use materials in which hydrogen is already present in the composition (e.g., chemical hydrides). The latter option seems to be the most promising since it permits a higher mass ratio of hydrogen. Recently, ammonia-borane complex (NH3BH3, AB) has been considered as solid hydrogen storage material since it possess one of the highest hydrogen contents (19.6 wt. %) and high stability under the moderate conditions. Hydrolysis and methanolysis are the two reactions liberating hydrogen from AB. However, a catalyst is needed for hydrogen generation from methanolysis of AB. In this context, we aim to develop PVP-stabilized palladium(0) and ruthenium(0) nanoclusters as catalyst for the methanolysis of AB. The PVP-stabilized palladium(0) and ruthenium(0) nanoclusters were prepared from the in-situ reduction of palladium(II) acetylacetonate and ruthenium(III) chloride respectively in the methanolysis of AB. The prepared palladium(0) nanoclusters were isolated as solid materials by removing the volatile in vacuum and characterized by using TEM, SAED, XPS, FT-IR, XRD and UV-visible electronic absorption spectroscopy techniques while and ruthenium(0) nanoclusters were characterized by TEM, XPS, XRD, FT-IR and UV-visible electronic absorption spectroscopy techniques. The kinetics of methanolysis of AB catalyzed by palladium(0) and ruthenium(0) nanoclusters were studied depending on the catalyst concentration, substrate concentration and temperature. The activation parameters of the catalytic methanolysis reaction obtained from the evaluation of kinetic data.

Os objetivos do presente trabalho foram: i) aprimorar o procedimento alternativo de mediação por íons metálicos da alcoólise da ligação peptidil-resina com vistas à obtenção de ésteres metílicos de peptídeos protegidos (Nα-acil-peptídeo protegido-OMe) em condição reacional branda e com alta eficiência; ii) investigar a aplicabilidade do procedimento para a preparação de Nα-acil-peptídeo protegido-SR e de Nα-acil-aminoácido-OR; iii) verificar se os Nα-acil-peptídeo-OMe obtidos atuariam como doadores de acila em reações de formação de ligação peptídica catalisadas por lipases. Para tanto, na busca da melhor condição de metanólise e comparação com os procedimentos usuais de alcoólise de ligação peptidil-resina, foram usados: o fragmento 22-24 da colecistocinina-33 humana (tripeptídeo modelo), Ca2+, Zn+2, Co+2 e Cu+2 (mediadores), as resinas oxima de Kaiser (KOR), p-hidroximetilfenil acetamidometil, ácido p-hidroximetilbenzóico e álcool p-benziloxibenzil (suportes poliméricos), misturas de MeOH com DCM, DMSO, NMP, THF ou DMF (solventes) e 25, 37, 50 ou 60°C. A condição ótima encontrada [KOR, Ca+2 (1 eq./eq. de peptídeo), 50% MeOH/DMF, 50°C] foi empregada com sucesso na preparação do Nα--acil-heptapeptídeo protegido-OMe, fragmento do peptídeo quimiotático M de Vespa mandarinia. Variações dessa condição foram usadas com sucesso nas preparações dos Nα-acil-tripeptídeo protegido-S(CH2)2COOEt e Nα-acil-Ala-OR (R: Me; Bzl), pois eles foram gerados com boas qualidades e rendimentos similares ou superiores aos obtidos via procedimentos usuais. Após desproteção de cadeias laterais, os Nα-acil-tripeptídeo-OMe e Nα-acil-heptapeptídeo-OMe foram usados em reações de acoplamento com Gly-NH2 em presença de preparações lipásicas comerciais. Estes ensaios inéditos também foram bem sucedidos, pois após adequação das condições reacionais, os Nα-acil-tetrapeptídeo-NH2 e Nα-acil-octapeptídeo-NH2 foram obtidos com boas qualidades e rendimentos de 65% (1 h) e 55% (24 h), respectivamente. / The present work aimed to: i) improve the alternative procedure based on mediation by metal ions of peptide-resin linkage alcoholysis to obtain fully protected peptide methyl esters (Nα-acyl-protected peptide-OMe) under mild reaction condition and with high efficiency; ii) investigate the usefulness of the alternative procedure for preparing Nα-acyl-protected peptide-SR and Nα-acyl-amino acid-OR; iii) verify whether the resulting Nα-acyl-peptide-OMe would act as acyl donors in peptide bond formation catalyzed by lipases. Thus, in the search for the best methanolysis condition and comparison with the usual procedures for that, we used: fragment 22-24 of human cholecystokinin-33 (model tripeptide), Ca+2, Zn+2, Co+2 and Cu+2 (mediators), Kaiser oxime resin (KOR), p-hydroxymethylphenylacetamido methyl resin, p-hydroxymethylbenzoic acid resin and p-benzyloxy benzyl alcohol resin (polymeric supports), mixtures of MeOH and DCM, DMSO, NMP, THF or DMF (solvents) and 25, 37, 50 or 60°C. The optimal condition found [KOR, Ca+2 (1 eq./eq. of peptide), 50% MeOH/DMF, 50°C] was used successfully for preparing Nα-acyl-protected heptapeptide-OMe, fragment 1-7 of the chemotactic peptide M produced by Vespa mandarinia. Variations of this condition were employed successfully for preparing Nα-acyl-protected tripeptide-SR and Nα-acyl-Ala-OR (R: Me, Bzl): indeed, these compounds were obtained in good quality and with similar or superior yields than those provided by usual procedures. After side chain deprotections, the Nα-acyl-tripeptide and Nα-acyl-heptapeptide methyl esters obtained were used in coupling reactions with Gly-NH2 in the presence of commercial lipase preparations. Those pioneer reactions were also successful, since after optimizing the conditions, Nalfa-acyl-tetrapeptide-NH2 and Nα-acyl-octapeptide-NH2 were obtained in good qualities with yields of 65% (1 h) and 55% (24 h), respectively.

Os objetivos do presente trabalho foram: i) aprimorar o procedimento alternativo de mediação por íons metálicos da alcoólise da ligação peptidil-resina com vistas à obtenção de ésteres metílicos de peptídeos protegidos (Nα-acil-peptídeo protegido-OMe) em condição reacional branda e com alta eficiência; ii) investigar a aplicabilidade do procedimento para a preparação de Nα-acil-peptídeo protegido-SR e de Nα-acil-aminoácido-OR; iii) verificar se os Nα-acil-peptídeo-OMe obtidos atuariam como doadores de acila em reações de formação de ligação peptídica catalisadas por lipases. Para tanto, na busca da melhor condição de metanólise e comparação com os procedimentos usuais de alcoólise de ligação peptidil-resina, foram usados: o fragmento 22-24 da colecistocinina-33 humana (tripeptídeo modelo), Ca2+, Zn+2, Co+2 e Cu+2 (mediadores), as resinas oxima de Kaiser (KOR), p-hidroximetilfenil acetamidometil, ácido p-hidroximetilbenzóico e álcool p-benziloxibenzil (suportes poliméricos), misturas de MeOH com DCM, DMSO, NMP, THF ou DMF (solventes) e 25, 37, 50 ou 60°C. A condição ótima encontrada [KOR, Ca+2 (1 eq./eq. de peptídeo), 50% MeOH/DMF, 50°C] foi empregada com sucesso na preparação do Nα--acil-heptapeptídeo protegido-OMe, fragmento do peptídeo quimiotático M de Vespa mandarinia. Variações dessa condição foram usadas com sucesso nas preparações dos Nα-acil-tripeptídeo protegido-S(CH2)2COOEt e Nα-acil-Ala-OR (R: Me; Bzl), pois eles foram gerados com boas qualidades e rendimentos similares ou superiores aos obtidos via procedimentos usuais. Após desproteção de cadeias laterais, os Nα-acil-tripeptídeo-OMe e Nα-acil-heptapeptídeo-OMe foram usados em reações de acoplamento com Gly-NH2 em presença de preparações lipásicas comerciais. Estes ensaios inéditos também foram bem sucedidos, pois após adequação das condições reacionais, os Nα-acil-tetrapeptídeo-NH2 e Nα-acil-octapeptídeo-NH2 foram obtidos com boas qualidades e rendimentos de 65% (1 h) e 55% (24 h), respectivamente. / The present work aimed to: i) improve the alternative procedure based on mediation by metal ions of peptide-resin linkage alcoholysis to obtain fully protected peptide methyl esters (Nα-acyl-protected peptide-OMe) under mild reaction condition and with high efficiency; ii) investigate the usefulness of the alternative procedure for preparing Nα-acyl-protected peptide-SR and Nα-acyl-amino acid-OR; iii) verify whether the resulting Nα-acyl-peptide-OMe would act as acyl donors in peptide bond formation catalyzed by lipases. Thus, in the search for the best methanolysis condition and comparison with the usual procedures for that, we used: fragment 22-24 of human cholecystokinin-33 (model tripeptide), Ca+2, Zn+2, Co+2 and Cu+2 (mediators), Kaiser oxime resin (KOR), p-hydroxymethylphenylacetamido methyl resin, p-hydroxymethylbenzoic acid resin and p-benzyloxy benzyl alcohol resin (polymeric supports), mixtures of MeOH and DCM, DMSO, NMP, THF or DMF (solvents) and 25, 37, 50 or 60°C. The optimal condition found [KOR, Ca+2 (1 eq./eq. of peptide), 50% MeOH/DMF, 50°C] was used successfully for preparing Nα-acyl-protected heptapeptide-OMe, fragment 1-7 of the chemotactic peptide M produced by Vespa mandarinia. Variations of this condition were employed successfully for preparing Nα-acyl-protected tripeptide-SR and Nα-acyl-Ala-OR (R: Me, Bzl): indeed, these compounds were obtained in good quality and with similar or superior yields than those provided by usual procedures. After side chain deprotections, the Nα-acyl-tripeptide and Nα-acyl-heptapeptide methyl esters obtained were used in coupling reactions with Gly-NH2 in the presence of commercial lipase preparations. Those pioneer reactions were also successful, since after optimizing the conditions, Nalfa-acyl-tetrapeptide-NH2 and Nα-acyl-octapeptide-NH2 were obtained in good qualities with yields of 65% (1 h) and 55% (24 h), respectively.

Orientador: Prof. Dr. Fernando Heering Bartoloni / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Ciência e Tecnologia/Química, Santo André, 2018. / No presente trabalho estudou-se a aplicabilidade de fluorescencia (FL) e quimiluminescencia (CL) para a determinacao de mecanismos de reacao envolvendo esteres, um deles um ester derivado de lofina. A lofina e seus derivados, em geral, apresentam rendimentos quanticos de fluorescencia (¿³FL) com valores relativamente altos (¿³FL > 0,1), tornando essas moleculas amplamente utilizadas em estudos CL e FL. A decomposicao do ester de lofina (acetato de 4-(4,5-difenil-1H-imidazol-2-il)fenila, 1) foi estudada em meio alcalino alcoolico utilizando como solventes MeOH e iPrOH, e como bases HO., tBuO., DBU e TEA. Duas metodologias de acompanhamento de cinetica por emissao foram comparadas: observando a formacao do produto (¿Éex = 350 nm e ¿Éem = 475 nm) e o consumo do ester 1 (¿Éex = 300 nm e ¿Éem = 400 nm). Ambas apresentaram resultados equivalentes para as constantes de velocidade observadas. Tanto em MeOH quanto em iPrOH, o possivel mecanismo ocorre por uma via classica BAC2, envolvendo a base conjugada do solvente (i.e., MeO. ou iPrO.) como nucleofilo, gerada por CBE quando HO., tBuO. e DBU foram empregados como catalisadores (kbim = 4,5.6,5 L mmol.1 s.1). Para TEA, uma constante kbim tres ordens de grandeza inferior foi obtida, representando uma possivel mudanca no mecanismo de reacao, provavelmente, para catalise nucleofilica. A solvolise neutra do ester se mostrou particularmente significativa quando baixas concentracoes de catalisador foram utilizadas. Na segunda parte deste trabalho, referente a reacao peroxioxalato, a degradacao do oxalato de bis(2,4,6-triclorofenila) (TCPO) foi estudada em MeOH e comparada ao sistema classico (em EtOAc, com catalise por imidazol). Ensaios cineticos de emissao e absorcao permitiram verificar que a metanolise se mostrou proeminente frente a peridrolise. Por ensaios de absorcao, foi possivel determinar que a primeira eliminacao de um residuo fenolico ocorre mais rapidamente que a segunda (kABS1 > kABS2), contrariamente ao observado no sistema classico, tanto para metanolise quanto peridrolise. Observou-se que a adicao de EtOAc ao meio protico polar muda o comportamento cinetico da reacao, aproximando-o ao do sistema classico. Propos-se um modelo cinetico final, indicando quais etapas sao lentas, rapidas e muito rapidas, dentro do processo estudado. / The use of fluorescence (CL) and chemiluminescence (FL) for the determination of reaction mechanisms involving esters was studied in this work, one of them is a lophine derived ester. Lophine and its derivatives generally have quantum fluorescence yields (ÖFL) with relatively high values (ÖFL> 0.1), making these molecules widely used in CL and FL studies. The decomposition of a lophine derived ester (4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl acetate, 1) was studied in basic alcoholic media using MeOH and iPrOH as solvents, and HO¿, tBuO¿, DBU and TEA as bases. Two methodologies for tracking emission kinetics were compared: observing product formation (ëex = 350 nm and ëem = 475 nm) and ester 1 consumption (ëex = 300 nm and ëem = 400 nm). Both methods showed equivalent results for the obtained observed rate constants. Possibly the reaction mechanism follows a BAC2 pathway, in both MeOH and iPrOH, involving the solvent conjugate base (i.e., MeO¿ or iPrO¿) as nucleophile, generated by SBC when HO¿, tBuO¿ and DBU were used as catalysts (kbim = 4.5¿6.5 L mmol¿1 s¿1). For TEA, the obtained kbim was three orders of magnitude smaller, indicating a possible change in reaction mechanism, probably to nucleophilic catalysis. The ester¿s neutral solvolysis showed to be particularly significant when low concentrations of catalyst were used. At the second section of this work, regarding the peroxyoxalate reaction, the degradation of bis(2,4,6-trichlorophenyl)oxalate (TCPO) was studied in MeOH and compared to the classical system (in EtOAc, with imidazole catalysis). Emission and absorption kinetic assays allowed to conclude that methanolysis overcomes perhydrolysis. Through absorption measurements, it was possible to verify that the elimination of the first phenolic residue occurs faster than the second (kABS1 > kABS2), contrarily to the observation in the classical system, for both methanolysis and perhydrolysis. It was observed that the addition of EtOAc to the protic polar media changes the kinetical behavior of the reaction, approximating it to the classical system. A final kinetic model was proposed, stating which are the slow, fast and very fast steps, within the studied process.

Ce travail décrit la synthèse, les propriétés et la réactivité de cages moléculaires covalentes composées de deux porphyrines, synthétisées avec succès par effet template du DABCO, par CuAAC introduisant des sites périphériques triazoles permettant de contrôler la taille de la cavité grâce à différents stimuli chimiques. Ces cages se composent de porphyrines base libre ou métallées au zinc(II), à l’aluminium(III) ou au cobalt(III). La coordination réversible d’ions Ag(I) ou Cu(I) aux triazoles des cages moléculaires permet de passer d’une conformation aplatie à une conformation ouverte. La protonation des sites basiques permet l’ouverture maximale de la cage. Concernant leur réactivité, les cages aux porphyrines d’Al(III) permettent de catalyser la méthanolyse d’un triester de phosphate. Les cages aux porphyrines de Co(III) catalysent la synthèse de carbonates cycliques à partir d’époxyde et de CO2, sans formation de polycarbonates et avec une conversion totale en présence de pyridine comme co-catalyseur. Les cages bis-porphyriniques ont démontré dans ces réactions, une activité catalytique supérieure à celle des métalloporphyrines de référence. / This work describes the synthesis, properties and reactivity of porphyrinic molecular cages. The successful synthesis of these covalent cages relies on a DABCO-CuAAC templated reaction, which enables to introduce triazole as peripheral binding sites. These cages incorporate either two free base porphyrins or zinc(II), aluminium(III) or cobalt(III) metalloporphyrins. Reversible coordination of Ag(I) or Cu(I) ions to the triazoles of the cages allows to control the cavity size and to switch between a flattened and an opened conformation. Protonation of the basic sites of the cage leads to its maximal expansion. Cages with Al(III) porphyrins have shown to act as catalyst in the phosphate triester methanolysis reaction. Cages with Co(III) porphyrins catalyze the synthesis of cyclic carbonates from CO2 and epoxide without formation of polycarbonate and with total conversion upon addition of pyridine as co-catalyst. In these reactions, the bis-porphyrinic cages have shown to behave as more efficient catalysts than the metalloporphyrin monomers used as reference.