Dissertations / Theses on the topic 'Basic catalysis'

En los últimos años, existe un creciente interés en la sustitución de viejas tecnologías por alternativas catalíticas más limpias para el desarrollo de procesos respetuosos con el medio ambiente para la industria química. De esta manera, es un desafío continuo encontrar nuevos catalizadores básicos capaces de realizar, con alta actividad y selectividad, las reacciones para la síntesis de productos de alto valor añadido tanto químicos como farmacéuticos. La investigación descrita en esta Tesis se ha centrado en el estudio de nuevos protocolos de síntesis para catalizadores básicos. Nuevos materiales con basicidad controlada, tipo hidrotalcita, se han sintetizado a lo largo de esta Tesis. Por otra parte, se ha desarrollado un nuevo protocolo de síntesis para líquidos iónicos alifáticos de cadena corta. Además, se presenta un amplio estudio de las propiedades físico-químicas de los líquidos iónicos sintetizados. Las propiedades básicas de los catalizadores desarrollados se han caracterizado por diversas técnicas y así como mediante el empleo de reacciones modelo. Por consiguiente, el trabajo realizado en esta Tesis permite avanzar en el diseño de nuevos sistemas catalíticos más activos y eficientes para su utilización en procesos de química fina.
In the last years, there is an increasing interest in substituting old technologies by cleaner catalytic alternatives to afford more environmental friendly processes in the chemical industry. In this way, it is a continuous challenge to find new base catalysts able to perform, with high activity and selectivity, reactions for the synthesis of pharmaceutical and fine chemicals.
The research described in this thesis has focused on the study of new synthesis protocols for base catalysts. New types of hydrotalcite-like materials with controlled basicity were obtained. Also, a new synthesis protocol for short aliphatic chain ionic liquids and an extensive study of their physico-chemical properties is presented. Their basic properties have been characterized by several techniques and by illustrative test reactions. The work done in this thesis can be regarded as a progress in the design of new catalytic systems, more active and efficient for use in fine chemical processes.

Como consecuencia de una demanda energética creciente, en los últimos años se ha incrementado la producción de biodiesel generándose un exceso de producción de glicerol y provocando que su precio disminuya considerablemente. Por este motivo, durante los últimos años la transformación del glicerol en otros compuestos de valor añadido es uno de los objetivos para la industria química y los grupos de investigación. En esta tesis se han desarrollado diferentes catalizadores basados en hidrotalcitas para la síntesis de glicerol carbonato a partir de la transesterificación del glicerol de una forma eficiente y en condiciones suaves de reacción
The valorisation of glycerol is nowadays an important target of scientific groups due to the great excess of glycerol by-product obtained as consequence of a growing biodiesel production. Catalytic processing of glycerol to more valuable chemicals is demonstrated by the large number of patents and articles reported until now. Glycerol carbonate is one of the most interesting chemicals obtained from catalytic modifications of glycerol. This work describes an approach for obtaining glycerol carbonate in a green and efficient form under soft conditions using layered double hydroxides as solid catalysts.

Transition-metal-catalyzed cross-coupling reactions are reliable tools for forging C–C bonds. The Engle Lab has previously pioneered the intermolecular difunctionalization of unactivated alkenes facilitated by nickel catalysis, where regioselectivity is controlled through the use of a bidentate directing group. A limitation of existing methods is that allyl groups have not yet been successfully incorporated, as the electrophile scope has been limited to alkyl and aryl species. Fundamentally, C–C p-bonds have served as key building blocks for the assembly of complex molecules, and the ability to introduce allyl moieties in a controlled manner enables diverse, downstream functionalization in multi-step synthesis. This work focuses on the use of diverse azaheterocycle directing groups connected to non-conjugated alkenes. Through the use of nickel catalysis, we have been able to successfully introduce and preserve allyl and cinnamyl species at the g-position and alkyl zinc nucleophiles at the b-position with high yield under mild conditions. This novel, 1,2-allylalkylation can accommodate a vast array of substituents with different electronic and steric properties (>20 examples). Our efforts have shifted to exploring different monodentate directing groups and to conduct mechanistic studies to shed light on the catalytic cycle. Interestingly, electron-rich electrophiles provide nearly quantitative NMR and isolated yields, whereas electron-poor electrophiles lead to lower yields. We report a competition experiment to further elucidate this mechanism. While isolated yields were generally higher for electron-rich groups, a competition between p-OMe and p-CF3 electrophiles led to preferential incorporation of the trifluoromethyl-substituted coupling partner, which supports oxidative addition as the product-determining step.

Environmental pollution by polychlorinated chlorinated organic wastes is of great concern. Catalytic hydrodechlorination is considered clean and efficient methodology for safe disposal of chlorinated organic wastes. This work aims at studying the catalytic hydrodechlorination reaction for the removal of environmentally polluting chlorinated organic wastes: 1,2,4-trichlorobenzene (1,2,4-TCB) and Trichloroethylene (TCE). The research has focused on evaluation of the activity, selectivity and stability of newly synthesized Pd based catalysts for hydrodechlorination of 1,2,4-trichlorobenzene and trichloroethylene. The first part, related to the HDC of 1,2,4-TCB, is to obtain active and stable catalyst for the hydrodechlorination of C-Cl bond of aromatic compounds to non chlorinated organic aromatic compound (benzene). While the second part aims at obtaining catalysts that allow high selectivity to ethylene formation during the HDC Trichloroethylene. Pd based hydrotalcite derived mixed oxides with different surface property were explored as catalysts for hydrodechlorination reaction. In addition, bimetallic and monometallic heterogeneous catalytic systems were investigated for selective hydrodechlorination reaction. Detailed characterization of the active centers of the newly synthesized catalysts by different techniques was achieved. This work presents original ideas, which could find a practical application, for the treatment of organo-halogenated pollutants.
La contaminación ambiental mediante compuestos policlorados aromáticos y alifáticos es de gran preocupación. La reacción de hidrodecloración catalítica selectiva (HDC) se presenta como una nueva tecnología eficaz para una eliminación segura de estos tipos de compuestos orgánicos clorados. Es por ello, que este trabajo de investigación se ha enfocado en el estudio de nuevos catalizadores activos, selectivos y estables en diferentes reacciones de hidrodecloración de dos familias de compuestos orgánicos clorados: 1,2,4-triclorobenceno (1,2,4-TCB-compuestos aromáticos clorados) y el tricloroetileno (representativo de un compuesto clorado alifático). La primera parte de la tesis relacionadas con el HDC de 1,2,4-TCB, tiene como objetivo la obtención de catalizadores activos y estables para la hidrogenación del enlace C-Cl en compuestos aromáticos y la obtención final del compuesto aromático orgánico declorado. Mientras que la segunda parte tiene por objeto la obtención de catalizadores que permitan una gran selectividad a etileno y no hacia etano (hidrogenación profunda del tricloroetileno) durante la HDC de tricloroetileno. Por otra parte se ha realizado un estudio profundo en la síntesis de estos nuevos catalizadores, así como en la caracterización de los centros activos de dichos catalizadores, para su correlación con la actividad, selectividad y estabilidad de dichos catalizadores. Presenta ideas originales, lo que podría encontrar una aplicación práctica, para el tratamiento de compuestos órgano-halogenados contaminantes.

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Universidade Federal de Sao Carlos
The investments in the biofuel production have increased a lot in the last years mainly because of smaller damages they cause to the environment in comparison with the derived conventional petroleum fuels. The reaction of biodiesel formation is denominated transesterification and, nowadays that reaction happens in the presence of homogeneous catalyst as the sodium methoxide, sodium hydroxide, (NaOH) or potassium hydroxide (KOH). However, those catalysts create problems such as the possibility of soap formation and they need stages such as the neutralization and washing of the biodiesel. Moreover, the residues of the hydroxides are aggressive to the environment. To eliminate these and other problems, the present work presents a new technology in heterogeneous catalysts with enough basic force to accomplish the transesterification of vegetable oil in tender conditions. For the first time, hybrid catalysts of the type molecular sieves of the family M41S ([CTA]Si-MCM-41, [CTA]Si-MCM-48 and [CTA]Si-MCM-50) were synthesized and used, without modification, in transesterification reactions with monoesters and vegetable oils. The results show that catalysts reach conversions around 96 % in the transesterification of canola oil (1:18) at 79 ºC, however the activity is reduced when the catalyst is reused, due, mainly, to the lixiviation of the CTA+ cation. However, new techniques are being developed in order to increase the catalyst stability.
Os investimentos na produção de biocombustíveis aumentaram significativamente nos últimos anos devido, principalmente, aos menores danos causados ao meio ambiente em comparação aos combustíveis convencionais derivados de petróleo. A reação de formação do biodiesel é denominada transesterificação e, atualmente, essa reação ocorre na presença de catalisador homogêneo como o metóxido de sódio, hidróxido de sódio (NaOH) ou de potássio (KOH). Entretanto, esses catalisadores possuem problemas como possibilidade de formação de sabões e necessitam de etapas como a neutralização e lavagem do biodiesel, além disso, os resíduos dos hidróxidos são agressivos ao meio ambiente. Para eliminar estes e outros problemas o presente trabalho apresenta uma nova tecnologia em catalisadores heterogêneos com força básica suficiente para realizar a transesterificação de óleos vegetais em condições amenas. Pela primeira vez, catalisadores híbridos do tipo peneiras moleculares da família M41s ([CTA]Si-MCM-41, [CTA]Si-MCM-48 e [CTA]Si-MCM-50) foram sintetizados e utilizados, sem modificação, em reações de transesterificação com monoésteres e óleos vegetais. Os resultados mostram que catalisadores atingem conversões em torno de 96 % na transesterificação de óleo de canola (1:18) a 79 ºC, porém a atividade é reduzida no reuso do catalisador, devido, principalmente, à lixiviação do cátion CTA+. Entretanto, novas técnicas estão em desenvolvimento para aumentar a estabilidade dos catalisadores.

Dans la présente étude, la compatibilité de molécules polyfonctionnelles a été évaluée en oxydation catalytique aérobie. L'oxydation du géraniol en citral a été réalisée dans un mélange t-BuOH/eau à 40°C en présence de Pt/C et Pt-Bi/C. A 90°C, l'oxydation sélective du 8-Chloro-1-Octanol en acide 8-Chlorooctanoïque a été réalisée. Par contre, d'autres substrats n'ont pas pu être transformés sélectivement en aldéhyde ou en acide à cause de leur sensibilité vis-À-Vis de l'oxygène (alcool-A) ou de leur réactivité particulière (5-Chloro-1-Pentanol qui est cyclisé en produits non désirés). En conditions anaérobies, le transfert d'H alcool / accepteur a été développé, à partir du géraniol (alcool allylique) comme substrat modèle : il convient de réaliser soit la déshydrogénation sélective de sa fonction alcool, soit son isomérisation lorsque la fonction alcool est déshydrogénée en même temps que la C=C allylique est hydrogénée. Les catalyseurs au Cu supporté ont montré un potentiel beaucoup plus prometteur que les métaux nobles, et de nombreux supports ont été évalués. Le styrène utilisé comme accepteur d'H ne permet pas d'obtenir sélectivement le produit de déshydrogénation du géraniol (citral), par contre l'utilisation d'un accepteur d'H confidentiel permet d'obtenir sélectivement le citral sans former de citronellal (produit d'isomérisation de la fonction alcool allylique) en présence de catalyseur au cuivre sur un support ex-Hydrotalcite. En l'absence d'accepteur, ce catalyseur permet l'isomérisation sélective de différents alcools allyliques avec des sélectivités jusqu'à 90 % en cétones saturées
In this study, we evaluated the compatibility of polyfunctional alcohols with catalytic aerobic oxidation systems. Geraniol dehydrogenation was carried out in mild conditions (t-BuOH / water mixture as solvent, 40°C) in the presence of Pt / C (promoted with Bi to avoid leaching). These catalysts are efficients for the oxidation of 8-Chloro-1-Octanol into corresponding acid at 90°C. However, other reactants were not selectively transformed into aldehyds or acids because of their oxygen sensivity (alcool-A) or their particular reactivity toward cyclization products (5-Chloro-1-Pentanol). In parallel, H transfer dehydrogenation was developed in anaerobic conditions. Geraniol was choosen as a model molecule since it can be selectively dehydrogenated or isomerizd (a reducible function on the substrate is hydrogenated when alcohol function is dehydrogenated). Some noble metals were evaluated for these reactions (Pd in the presence of alkene as H acceptor or Ag for acceptorless dehydrogenation), but performances and selectivities are quite low. Copper catalysts showed better results, and a lot of supports were evaluated. Selectivity toward dehydrogenation product (citral) is not total when styrene is used as hydrogen acceptor, but the use of another H acceptor (confidential) in the presence of copper supported on modified hydrotalcite catalyst allows selective dehydrogenation of geraniol without isomerization intro citronellal. Without H acceptor, this catalyst leads to selective isomerization of secondary allylic alcohols into saturated ketones (90 % selectivity)

Dans le contexte de la valorisation de la biomasse par catalyse hétérogène, la chimie théorique est essentielle pour guider la détermination de la nature des sites actifs en combinaison avec des caractérisations expérimentales. Ensuite, le mécanisme de réaction peut être étudié pour déterminer l’état de transition et intermédiaire déterminant la vitesse et ensuite concevoir de meilleurs catalyseurs in silico. Nous avons mis en œuvre cette approche dans plusieurs réactions impliquant des alcools qui jouent un rôle clé dans le passage du pétrole à la biomasse comme source de matière première pour les produits chimiques de commodités ou spécialités. Tout d'abord, nous nous sommes concentrés sur l'oxydation des alcools en phase liquide par l'oxygène, une réaction qui nécessite généralement un environnement alcalin, ce qui nuit à l'économie d’atomes du processus car il génère le sel carboxylate au lieu de l'acide carboxylique. Nous avons proposé un modèle d'interface métal / eau basique incluant l'adsorption d'anion hydroxyde. Cet anion charge la surface métallique et modifie son activité catalytique. Ce modèle a tout d’abord été validé en comparant l’activité prédite de Au et de Pt en présence et en l’absence de base, puis a été utilisé pour étudier l’oxydation d’éthoxylates d’alcool par des bimétalliques. Ensuite, nous sommes passés à la déshydratation en phase gazeuse d’alcools en C3 et C4 en utilisant des catalyseurs à base de phosphate. La modélisation des surfaces s’est basée sur des caractérisations expérimentales. La couverture moléculaire de l'eau à la surface en fonction de la pression et de la température a été établie à l'aide de la thermodynamique ab initio. Les simulations de spectres infrarouges d'adsorption de CO, NH3 et C2H2 nous ont permis d'identifier les sites acido-basiques qui jouent un rôle important dans l'investigation du mécanisme de réaction qui a suivi
In the context of biomass valorization by heterogeneous catalysis, computational chemistry is key to provide guidance to establish the nature of the active sites in combination with experimental characterizations. Then, the reaction mechanism can be studied to determine the rate determining transition state and intermediate and further design in silico better catalysts. We implemented this approach in several reactions involving alcohols that are key in the shift from a petroleum chemical feedstock to a biomass-based feedstock. Firstly, we focused on liquid phase alcohol oxidation by oxygen, a reaction that generally requires an alkaline environment, which is detrimental to the atom economy of the process since it generates the carboxylate salt instead of the carboxylic acid. We proposed a model of metal/basic water interface that includes the adsorption of hydroxide anion. It charges the metallic surface and modifies its catalytic activity. This model was first validated comparing the predicted activity of Au and Pt in presence and in absence of a base, and then used oxidation of alcohol ethoxylates by bimetals. Then, we switched to gas phase dehydration of C3 and C4 alcohols using phosphate-based catalysts. The modeling of the surfaces was based on experimental characterizations. The molecular coverage of water on the surface in function of the pressure and temperature was established using ab initio thermodynamic. The simulations of infrared spectra of CO, NH3 and C2H2 adsorption allowed us to identify the acido-basic sites which play an important role in the reaction mechanism investigation that followed

2009/2010
Nanosized inorganic particles constitute a field of rapidly growing interest and their tailored synthesis is currently subject of intense study. These particles may show unique properties that are not shared by bulk materials and therefore find a palette of innovative applications, e.g., as diagnostic means, or in drug and even gene delivery, offering the advantage over polymer nanoparticles because they are stable, biologically inert, biocompatible and it is easy to introduce functional groups by modification of the surface hydroxyls. Among various synthetic routes the most explored are the ones carried out in bulk, especially the Stöber synthesis, however the final product are mostly polydisperse particles whose size is difficult to control. On the other hand, w/o microemulsion is providing suitable environment for the control of the particle nucleation and growth kinetics, as the nanodroplets of water are nanoreactors for the synthesis. The main advantage is that the procedure does not require extreme conditions of temperature and pressure and the particle size and shape can be controlled simply by controlling the microemulsion parameters where the most important are the water-to-surfactant molar ratio, R, and water-to-TEOS molar ratio, h. The previous studies focused on the latter synthetic route, in base-catalyzed systems, concerned mainly the evolution of silica nanoparticles and the best results were achieved by SAXS. The volume fraction versus time data gave an insight into nucleation and growth and is in agreement with first order kinetics with respect to TEOS concentration. However, we wanted to understand better the environment in which the synthesis takes place and shed light on the evolution of the soluble species, both of the constituents of the microemulsion and of those taking part to reaction. The soluble species present in the reaction mixture that leads to silica nanoparticle production through the base catalyzed hydrolysis of tetraethyl orthosilicate (TEOS) and the successive condensation were investigated in situ, under the actual synthesis conditions, by means of 1H, 13C, and 29Si NMR spectroscopy. The two former nuclei, owing to higher sensitivity and their presence both in the reacting species and in the constituents of the w/o microemulsion (cyclohexane-Igepal CA520 (5 polyoxyethylene iso-octylphenyl ether)-concentrated ammonia solution) afforded insight into the inverse microemulsion and allowed us to assess the kinetic rate of the hydrolysis step. It was verified that the microemulsion microstructure is maintained during the reaction. Special attention was paid to the reaction medium, and an extended assignment of the 1H and 13C resonances of the surfactant head group was performed. These head group signals undergo some changes due to the environmental modifications induced by transition from cyclohexane solution to w/o microemulsion and further to NH3 containing w/o microemulsion. We followed the quantitative evolution of TEOS and EtOH and assessed their preferential distribution in the various environments provided by this, on the mesoscale heterogeneous, reaction medium. Most authors agree that TEOS is localized mainly in the oil however they argue whether EtOH is preferentially in the water-pools or in oil. The clarification was achieved by means of PGSTE NMR since the diffusion coefficients are commonly exploited to characterize microemulsions, to determine the connectivity of the phase and they can be used to obtain the size of water droplets. It was revealed that NH3 exchanges among the inverse micelles diffusing through cyclohexane and confirmed that the preferred localization for ethanol, a byproduct of the reaction, is the bulk oil. Moreover, it was confirmed that TEOS is localized mainly in the oil. The characterization of the final nanoparticles was carried out by means of transmission electron microscopy (TEM) and it was revealed that the final product were monodispersed particles with radius of 20 nm. The synthesis of SiO2 nanoparticles in an acid-catalyzed system is especially interesting from nanotechnological point of view, owing to the different physical nature of silica synthesized under acidic rather than basic conditions, and from an applicative point of view since intended guest species are not always base resistant. Unfortunately, the application of an acid-catalyzed sol-gel process seems less than straightforward. An inverse microemulsion looks like an optimal reaction medium able to limit the growth of silica particles within the nanometer range. However, relatively few studies have been reported to date, and to the best of our knowledge, only one involves the entire process conducted in an inverse microemulsion with a water core that remains stable throughout the course of the reaction. The cyclohexane-Igepal inverse microemulsion, comprehensively established for the synthesis of silica nanoparticles in NH3-catalyzed sol-gel process, was alternatively studied with an acid-catalyzed sol-gel process. TEOS was used as the silica precursor, while two different aqueous phases containing either HNO3 or HCl at two different concentrations, 0.1 and 0.05 M, were examined in the presence and in the absence of NaF, a catalyst of the condensation step. The evolution of the overall reacting system, specifically hydrolysis and polycondensation of reaction intermediates, was monitored in situ by SAXS. No size variation of the inverse micelles was detected throughout the sol-gel process. Conversely, the density of the micellar core increased after a certain time interval, indicating the presence of the polycondensation product. The IR spectra of the reacting mixture were in agreement with such a hypothesis. 1H and 13C NMR measurements provided information on the soluble species, the surfactant, and TEOS. The TEOS consumption was well fitted by means of an exponential decay, suggesting that a first-order kinetics for TEOS transpires in the various systems examined, with rate constants dependent not only on the acid concentration but also on its nature (anion specific effect), on the presence of NaF, and on the amount of water in the core of the inverse micelle. The self-diffusion coefficients, determined by means of PGSTE NMR, proved that a sizable amount of the byproduct ethanol was partitioned inside the inverse micelles. Moreover, the DOSY spectrum contributed to the assignment of the signals of various oligomeric species present in the commercial mixture of Igepal CA520, since the head group, which is a short polyoxyehtylene chain, is somewhat polydisperse. The embedment of Igepal CA520 in an acid-catalyzed inverse microemulsion led to the separation of 1H signals of the various oligomeric components. This ensued from the differential partitioning between the oil and the surface of the inverse micelles, which depends on the ethyleneoxide number (EON) of the head group and the partition degree, between the two environments, for each individual oligomeric species, and afforded further insight into nonionic inverse microemulsions. It was possible to ascertain that the length distribution of the polyethyleneoxide chains is in good agreement with the Poisson distribution theoretically predicted for the polymerization of ethylene oxide. Characterization of the final product was carried out by means of thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and TEM, which concurrently confirmed that the silica isolated from the inverse nonionic microemulsion is not significantly different from the product of a bulk acid-catalyzed sol-gel synthesis. TEM micrographs illustrated particles with diameters smaller than the diameter of the inverse micelles as determined by SAXS, due to a shrinkage effect, in addition to nanostructured aggregates in the range 20-100 nm. The metal doped silica systems are important for optical applications and if the metal ions are finely dispersed on silica matrix very efficient catalysators can be obtained. The synthesis of silica nanoparticles in HCl-catalyzed inverse microemulsion was carried out in the presence of both Cu2+ and Co2+ ions with the aim to get correspondingly doped nanoparticles. The systems were characterized by means of 1H and 13C NMR and the quantitative evolution of TEOS and EtOH was followed. The introduction of metals in the glass matrix strongly influences their optical visible absorption spectrum so the UV-Vis spectroscopy was applied in the study. The isolated nanoparticles were characterized by means of IR and Raman spectroscopy and their size was determined by TEM. It was demonstrated that inverse micelles can be used to produce Co2+ and Cu2+ doped SiO2 nanoparticles with diameter of about 3 and 4 nm, respectively. Spherical particles smaller than the micellar size and, in the case of Cu2+ doped system, larger, irregularly shaped aggregates with diameter up to 1 μm were observed. Lots of darker zones were observed in the TEM images of some larger particles and aggregates containing Cu and may be assigned to Cu metal particles encapsulated in silica matrix. Therefore, cobalt was successfully doped in silica nanoparticles while copper doping seemed less satisfactory.
Particelle inorganiche di grandezza nanometrica costituiscono un settore di interesse in rapida crescita e la loro sintesi è attualmente oggetto di intenso studio. Queste particelle possono presentare proprietà uniche non condivise da materiali bulk e quindi trovare una vasta gamma di applicazioni innovative, ad esempio, come mezzo diagnostico, o per drug delivery e anche gene delivery, offrendo il vantaggio rispetto nanoparticelle polimeriche di essere stabili, biologicamente inerti, biocompatibili e facilmente funzionalizzabili con gruppi funzionali modificando dei ossidrili superficiali. Tra le varie vie sintetiche più esplorate sono quelle effettuate in bulk, in particolare la sintesi di Stöber, ma il prodotto finale sono particelle per lo più polidisperse la cui dimensione è difficile da controllare. D'altra parte, la microemulsione a/o sta fornendo l'ambiente adatto per il controllo della cinetica di nucleazione e crescita delle particelle, siccome le nanogoccioline d'acqua sono i nanoreattori per la sintesi. Il vantaggio principale è che la procedura non richiede condizioni estreme di temperatura e pressione e la dimensione delle particelle e la forma possono essere controllati semplicemente attraverso il controllo dei parametri di microemulsione tra cui i più importanti sono il rapporto molare acqua-tensioattivo, R, e acqua-TEOS, h. Gli studi precedenti focalizzati su quest'ultima linea sintetica, nei sistemi base-catalizzati, riguardavano principalmente l'evoluzione delle nanoparticelle di silice ed i migliori risultati sono stati raggiunti con SAXS. I dati di frazione di volume in funzione del tempo hanno fornito informazioni sui processi di nucleazione e di crescita e sono in accordo con una cinetica di primo ordine rispetto alla concentrazione di TEOS. Tuttavia, era importante capire meglio l'ambiente in cui la sintesi accade e mettere in luce l'evoluzione della specie solubile, sia dei componenti della microemulsione che di coloro che prendono parte alla reazione. Le specie solubili presenti nella miscela di reazione che porta alla produzione di nanoparticelle di silice attraverso l’idrolisi base-catalizzata di tetraetile ortosilicato (TEOS) e la successiva condensazione sono state studiate in situ, alle condizioni effettive di sintesi, mediante spettroscopia NMR di 1H, 13C, e 29Si. I primi due nuclei, a causa di una maggiore sensibilità e la loro presenza sia nel reagente che nei componenti della microemulsione a/o (cicloesano-Igepal CA520 (5 poliossietilene iso-octilfenil etere)-soluzione di ammoniaca concentrata) hanno offerto una visione della microemulsione inversa e ci hanno permesso di valutare la velocità di idrolisi. È stato verificato che la microstruttura della microemulsione è mantenuta durante la reazione. L’attenzione è stata rivolta particolarmente verso il mezzo di reazione, ed è stata effettuata un’assegnazione estesa delle 1H e 13C risonanze della testa del tensioattivo. Questi segnali della testa subiscono variazioni a causa delle modificazioni ambientali indotte dal passaggio dalla soluzione di cicloesano a microemulsione a/o e in seguito alla microemulsione a/o contenente NH3. Abbiamo seguito l'evoluzione quantitativa del TEOS e EtOH e valutato la loro distribuzione preferenziale nei vari ambienti forniti da questo mezzo di reazione, eterogeneo sulla mesoscala. Molti autori concordano sul fatto che il TEOS è localizzato principalmente in olio. Tuttavia, si dibatte se EtOH si trova preferenzialmente nelle goccioline d'acqua o nell’olio. Il chiarimento è stato realizzato per mezzo di PGSTE NMR in quanto i coefficienti di diffusione sono comunemente sfruttati per caratterizzare le microemulsioni, per determinare la connettività delle fasi e possono essere utilizzati per ottenere le dimensioni delle goccioline d’acqua. È stato rivelato che NH3 scambia tra le micelle inverse diffondendo attraverso il cicloesano ed è stato confermato che la localizzazione preferita per l'etanolo, il sottoprodotto della reazione, è l'olio. Inoltre, è stato confermato che il TEOS è localizzato principalmente nell’olio. La caratterizzazione delle nanoparticelle finali è stata effettuata per mezzo di microscopia elettronica a trasmissione (TEM) ed è stato rivelato che il prodotto finale sono le particelle monodisperse con raggio di 20 nm. La sintesi di nanoparticelle di SiO2 in un sistema con catalisi acida è particolarmente interessante dal punto di vista nanotecnologico, a causa della diversa natura fisica di silice sintetizzata in condizioni acide, piuttosto che in quelle basiche, e da un punto di vista applicativo in quanto le specie ospite previste non sempre sono resistenti alle basi. Purtroppo, l'applicazione di un processo sol-gel catalizzato da acido è meno chiara. Una microemulsione inversa sembra un mezzo di reazione ottimale in grado di limitare la crescita delle particelle di silice alle grandezze nanometriche. Tuttavia, relativamente pochi studi sono stati riportati fino ad oggi, e al meglio delle nostre conoscenze, solo uno riguarda l'intero processo condotto in una microemulsione inversa con un nucleo d’acqua che rimane stabile durante tutto il corso della reazione. La microemulsione inversa cicloesano-Igepal, stabilita per la sintesi di nanoparticelle di silice in processo sol-gel NH3-catalizzato, in alternativa è stata studiata con il processo sol-gel catalizzato da acido. Il TEOS è stato utilizzato come precursore di silice, mentre diverse fasi acquose contenenti HNO3 o HCl a due differenti concentrazioni, 0.1 o 0.05 M, sono state esaminate in presenza ed in assenza di NaF, un catalizzatore della fase di condensazione. L'evoluzione del sistema reagente complessivo, in particolare l’idrolisi e la policondensazione dei intermedi di reazione, è stata monitorata in situ mediante SAXS. Nessuna variazione delle dimensioni delle micelle inverse è stata rilevata durante tutto il processo sol-gel. Al contrario, è aumentata la densità dell’interno micellare dopo un certo intervallo di tempo, indicando la presenza del prodotto di policondensazione. Gli spettri IR della miscela di reazione erano d'accordo con tale ipotesi. Misure NMR 1H e 13C hanno fornito le informazioni sulle specie solubili.. Il consumo di TEOS era in accordo con un decadimento esponenziale, suggerendo una cinetica di primo ordine in TEOS, con costante di velocità dipendente non solo dalla concentrazione di acido, ma anche dalla natura (effetto anione specifico), dalla presenza di NaF, e dalla quantità di acqua nel nucleo della micella inversa. I coefficienti di auto-diffusione, determinati mediante PGSTE NMR, hanno dimostrato che una quantità considerevole del sottoprodotto etanolo è presente all'interno delle micelle inverse. Inoltre, lo spettro DOSY ha contribuito alla assegnazione dei segnali delle varie specie oligomeriche presenti nella miscela commerciale di Igepal CA520, poiché la testa, che è una breve catena di poliossietilene, è un po’ polidispersa. L’inserimento di Igepal CA520 in una microemulsione inversa contenente acido ha portato alla separazione di segnali 1H dei vari componenti oligomerici. Questo risulterebbe dal partizione differenziale tra l'olio e la superficie delle micelle inverse, che dipende dal numero di ossido di etilene (EON) della testa e il grado di partizione, tra i due ambienti, per ogni singola specie oligomerica, offrendo una visione più completa sulle microemulsioni inverse non ioniche. È stato possibile accertare che la distribuzione della lunghezza delle catene poliossietileniche è in buon accordo con la distribuzione di Poisson teoricamente prevista per la polimerizzazione di ossido di etilene. La caratterizzazione del prodotto finale è stata effettuata mediante analisi termogravimetrica (TGA), calorimetria differenziale a scansione (DSC), e TEM, che contemporaneamente hanno confermato che la silice isolata dalla microemulsione inversa non ionica non è significativamente diversa dal prodotto di sintesi sol-gel da catalisi acida in bulk. Le micrografie TEM hanno illustrato, oltre ad aggregati nanostrutturati nel range 20-100 nm, le particelle con diametro inferiore al diametro delle micelle inverse ,determinato da SAXS, a causa di un effetto di contrazione. I sistemi di silice dopati con metalli sono importanti per le applicazioni ottiche, e se gli ioni metallici sono finemente dispersi in matrice di silice possono essere ottenuti catalizzatori molto efficienti. La sintesi di nanoparticelle di silice in microemulsione inversa catalizzata da HCl è stata effettuata in presenza di entrambi ioni, Cu2+ e Co2+, con l'obiettivo di ottenere le nanoparticelle conseguentemente dopate. I sistemi sono stati caratterizzati mediante 1H e 13C NMR ed è stata seguita l'evoluzione quantitativa di TEOS e EtOH. L'introduzione dei metalli nella matrice vetrosa influenza fortemente il loro spettro di assorbimento ottico visibile per cui nello studio è stata applicata la spettroscopia UV-Vis. Le nanoparticelle isolate sono state caratterizzati mediante spettroscopia IR e Raman e la loro dimensione è stata determinata mediante TEM. È stato dimostrato che le micelle inverse possono essere utilizzate per produrre le nanoparticelle di SiO2 dopate di Co2+ e Cu2+ con diametro di circa 3 e 4 nm, rispettivamente. Sono state osservate le particelle sferiche più piccole rispetto alle dimensioni micellari e, nel caso del sistema dopato di Cu2+, aggregati più grandi di forma irregolare con diametro fino a 1 micron. Nei immagini TEM di alcune particelle più grandi e aggregati contenenti Cu sono state osservate molte zone più scure che possono essere assegnate alle particelle di metallo Cu incapsulato in matrice di silice. Pertanto, il cobalto è stato dopato con successo nelle nanoparticelle di silice, mentre il doping con il rame sembrava meno soddisfacente.
XXIII Ciclo
1983

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In order to increase accessibility to catalytic sites, several studies currently aimed at reducing the diameter of the particles of zeolites to the nanometer scale. So, the increase in aging temperature caused a reduction in the size of the particle to 40 ° C, higher values for the phenomenon of crystal growth has become prevalent. At temperatures between 50 ° C and above, evidenced the formation of materials with relative crystallinity, even before the hydrothermal treatment step. On aging at 60 ° C for 24 h, according to the XRD patterns and the use of the Scherrer equation was obtained the smaller crystallite sizes of all the syntheses performed, those having dimensions of about 12 nm and particle of 300 nm. Thus, when the synthesis time compared to the literature, there obtained a reduction of 54 h and no more necessary to make the hydrothermal treatment step at 100 ° C. To evaluate the influence of the size of the zeolite crystals, when they apply the basic catalysis, using the commercial and nanometric zeolites synthesized. Both materials modified by ion exchange with ammonium cations and methylammonium, in order to generate catalytic sites with strong basic properties. Due to steric hindrance ion exchange not completely occurred, however the nanometric zeolite showed values of ion exchange higher for all cations used for commercial zeolite, except for the tetramethylammonium cation, where the results were equal. Among all exchangers used cations, zeolites containing methylammonium had better conversions. The catalytic evaluations conducted have shown overall prevalence of catalysts with nanosized front of commercial micrometric zeolite. The greater accessibility and better diffusion of the reactants and products through the pores of zeolites with nanosized crystallites provided better performance in catalytic studies on activity, kinetics, reaction rate, activation energy and TOF.
Com o objetivo de aumentar a acessibilidade aos sítios catalíticos, inúmeras pesquisas são realizadas atualmente visando a redução do diâmetro das partículas das zeólitas para a escala nanométrica. Assim, a fim de aperfeiçoar e reduzir o tempo de síntese da zeólita FAU nanométrica foram empregadas algumas modificações no método reportado na literatura sem a utilização de direcionadores orgânicos. O aumento da temperatura de envelhecimento proporcionou a redução do tamanho das partículas até 40°C, para valores superiores o fenômeno de crescimento tornou-se predominante. Na temperatura de 50°C e superiores, evidenciou-se a formação de materiais com relativa cristalinidade antes mesmo da etapa de tratamento hidrotérmico. No envelhecimento a 60°C por 24 h, de acordo com os difratogramas e com o emprego da equação de Scherrer foram obtidos os menores tamanhos de cristais dentre todas as sínteses realizadas, estes possuindo dimensões em torno de 12 nm. Em uma avaliação catalítica preliminar utilizando todas as zeólitas sintetizadas na forma sódica, na reação modelo de condensação de Knoevenagel, os melhores resultados foram obtidos pela zeólita constituída de cristais de 12 nm e partículas de 300 nm. Desse modo, quando comparado o tempo de síntese com a literatura, atingiu-se uma redução de 54 h, além de não ser mais necessária a etapa de tratamento hidrotérmico a 100°C. Para avaliar a influência do tamanho dos cristais zeolíticos quando estes aplicados à catálise básica, utilizou-se as zeólitas comercial e nanométrica sintetizada no trabalho. Ambos os materiais foram modificados por troca iônica com cátions de amônio e metilamônio, objetivando a geração de sítios catalíticos com propriedades básicas mais fortes. Devido a impedimentos estéricos a troca iônica não ocorreu totalmente, porém, a zeólita com cristais de 12 nm apresentou valores de troca iônica superiores para todos os cátions utilizados em relação a zeólita comercial, exceto para o cátion tetrametilamônio, em que os resultados foram similares. Dentre todos os cátions trocadores utilizados, as zeólitas contendo monometilamônio apresentaram melhores conversões. As avaliações catalíticas realizadas demostraram melhor desempenho dos catalisadores nanométricos frente a zeólita micrométrica comercial. A maior acessibilidade e a melhor difusão dos reagentes e produtos pelos poros da zeólita nanométrica, proporcionaram melhores resultados nos estudos catalíticos referentes a atividade, cinética, velocidade da reação, energia de ativação e TOF.

Neste trabalho foi sintetizado o corante (E)-2-[3-[4-(difenilamina)-fenil]-1-(p-tolil)- alilideno]-malononitrila (DFTAM), a partir da reação de condensação entre 4- (difenilamino)-benzaldeído e 2- [1- (4- metilfenil)-etilideno]-malononitrila, com catálise básica de piperidina. O produto obtido foi purificado por cromatografia líquida de alta eficiência (HPLC) e caracterizado pelas técnicas de espectrometria de massas, ressonância magnética nuclear de 13C e 1H e espectroscopia no infravermelho com transformada de Fourier. Para estudar suas propriedades fotofísicas, espectros de absorção e emissão de fluorescência, decaimento de fluorescência e espectro de absorção de transientes foram feitos em diferentes solventes, variando-se a polaridade e viscosidade do meio. Duas bandas de absorção foram observadas, uma em 303 nm e outra em cerca de 490 nm, a qual apresentou deslocamento batocrômico com o aumento da polaridade do solvente. Para essa região de excitação a banda de emissão variou entre 517 e 630 nm, com o aumento da polaridade do meio. Os decaimentos de fluorescência mostraram duas componentes, uma na ordem de picossegundos e a outra de nanossegundos. Os experimentos de absorção de transientes apresentaram três espécies, uma mais longa (maior que 10 ms) e duas outras de cerca 2 e 22 μs. Surfactantes catiônicos, não iônico, e aniônico também foram usados para produzir micelas e fazer os experimentos já citados. Pôde-se observar que o corante interagiu com as micelas, melhorando sua fluorescência e aumentando o tempo de vida do estado singleto. Por fim, acompanhou-se in situ, através da técnica de microscopia TIRF, a reação de formação de DFTAM a nível single molecule com catalise básica de nanopartículas de MgO e lamínulas de vidro funcionalizadas com piperazina. Através da intermitência de fluorescência dos filmes feitos de ambas as amostras, observou-se a formação de moléculas do corante através de ciclos de catálise da piperazina.
In this project the synthesis of (E) -2- [3- [4- (diphenylamine) phenyl] -1- (p-tolyl) - allylidene] -malononitrile (DFTAM) dye, from the condensation reaction between 4- (diphenylamino) benzaldehyde and 2- [1- (4-methylphenyl) ethylidene]-malononitrile using piperidine basic catalysis has been achieved. The dye was purified by high-performance liquid chromatography (HPLC) and characterized by mass spectrometry, nuclear magnetic resonance 13C and 1H and Fourier Transform infrared spectroscopy techniques. To study DFTAM photophysical properties, absorption and fluorescence emission spectra, fluorescence decay and transient absorption spectrum were recorded in solvents with different polarity and viscosity. Two absorption bands of DFTAM were observed, the first one at 303 nm was solvent independent while the second one at about 490 nm, had bathochromic shift with increasing polarity of the medium. In the visible region of excitation the maximum of the dye emission band observed varied between 517 and 630 nm, upon increasing solvent polarity. Fluorescence decays showed two distinct components, a fast one in picosecond time scale and a slow one in nanoseconds. Transient absorption experiments indicated the presence of three species with different lifetimes, one longer than 10 ms and the other two with lifetimes about 2 and 22 μs. Cationic, nonionic, anionic surfactants were also used to produce micelles for easy solubilization of DFTAM. It was observed that the dye interacted with the micelles, improving its fluorescence yield and lifetime. Finally, the DFTAM formation reaction was monitored in situby TIRF wide field microscopy technique at single molecule level. The basic catalysis was tested for MgO nanoparticles and glass surface functionalized with bound piperazine. Through the fluorescence intermittency time trace obtained from TIRF movies, the discrete formation of dye molecules was only observed in the case of piperazine catalytic cycles.

Glycerol and fructose are molecules that are readily available in substantial quantities fromthe biomass. In this work dehydration routes for valorization of these compounds wereinvestigated. Therefore, zirconia and titania based catalysts, and calcium phosphate materialswere prepared and evaluated in the glycerol dehydration in gas phase. Niobia-ceria mixedoxides and mesoporous Nb2O5-MeO2 (M = Ce, Zr, Ti) mixed oxides were prepared andtested in fructose dehydration reaction in aqueous phase. The surface acid-base properties ofthe studied catalysts were correlated to their catalytic performance.

Dihydrofolate reductase (DHFR) is the enzyme that catalyses the reduction of 7,8-dihydrofolate (DHF) to 5,6,7,8-tetrahydrofolate (THF) in the presence of the cofactor reduced nicotinamide adenine dinucleotide phosphate (NADPH). The DHFR catalysed reaction has often been used to study enzymatic tunnelling and the contribution of protein dynamics to catalysis. To gain a better understanding of such phenomena and to investigate the key elements of structural adaptation in DHFR, in this thesis the hydride transfer reaction of DHFR from Moritella profunda (MpDHFR), a cold adapted enzyme, was studied and compared to the mesophilic and extensively studied enzyme from Escherichia coli (EcDHFR) and the thermophilic enzyme from Thermotoga maritima (TmDHFR). Chapter 1 gives a brief introduction to the thesis. Description of the materials and methods used in evaluating this work is reported in Chapter 2. In Chapter 3, the steady state and pre-steady state temperature dependences of the kinetic isotope effect (KIE) for the MpDHFR catalysed reaction was elevated, compared to data obtained for the mesophilic and the thermophilic DHFR homologues and the results interpreted according to the environmentally coupled tunnelling model. The work presented in Chapters 4 and 5 has investigated the role of dynamics during catalysis by DHFR using site directed mutagenesis. In Chapter 4, mutations were created in the GH loop for both EcDHFR and MpDHFR to elucidate the role of the occluded conformation during catalysis by DHFR. In Chapter 5, different MpDHFR and EcDHFR variants in the highly mobile M20 loop were generated and their temperature dependences of KIE were studied in addition to studying the two variants MpDHFR-G123V and MpDHFR-D124N in the catalytically important FG loop. The results obtained suggest that MpDHFR does not undergo the dynamical loop movements that have been recognized previously for EcDHFR in spite of following the same catalytic cycle. Further findings were found which contradict the current models that relate protein dynamics to catalysis efficiency, thus modifying these models has become essential. Chapter 6 has focused on studying the effect of different denaturants/salt concentrations on MpDHFR chemical step. Finally, a summary of the work presented in this thesis and future guidelines are provided in Chapter 7.

Thesis advisor: Marc L. Snapper
Chapter 1. Review of concept and methodology development for asymmetric allylation of carbonyls and imines. Chapter 2. Description of the catalytic asymmetric addition of allyltrichlorosilane to aldehydes catalyzed by a proline-based N-oxide catalyst. Chapter 3. Introduction of the first catalytic asymmetric silylation of alcohols for desymmetrization of meso-diols. Chapter 4. Presentation of asymmetric silylation for synthesis of chiral syn-1,2-diols by kinetic resolution or divergent reaction on a racemic mixture
Thesis (PhD) — Boston College, 2008
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Chemistry

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico
The hydrotalcites are a class of layered double hydroxides with important physical and chemical properties. The use of this class of compounds in catalysis of specific reactions also requires many studies. The literature has exploited these materials in catalytic reactions in liquid phase with glycerol, particularly in hydrogenolysis reactions. The gas phase reactions with glycerol usually make use of acid catalysts. Thus, both the liquid phase reactions involving catalysts derived from hydrotalcite-like gas phase reactions involving basic catalysts require further study. We developed a study to elucidating the combined effects of basic catalytic sites (MgO and amorphous aluminum oxide) and dehydrogenation (derived from copper oxides) in the hydrogenolysis reaction. The materials used were derived from hydrotalcite oxides, and oxides derivatives containing in its composition 2.5% copper (molar ratio) in relation to the metal network hydrotalcite (Mg and Al). The results obtained for the gas phase show an interrelationship between the sites and the major products of the reaction, acetol and acrolein. Was determined conditions under which one or another product is more favored, with conversions that can reach over 90% and selectivities that exceed 99%. In the liquid phase this interrelationship is more difficult to be demonstrated, given the complications arising from the greater contact time between catalyst and reactants to the point of the major products at the reaction gas phase includes both as reaction intermediates in the liquid phase. In the liquid phase, the predominant carbon chain compounds of higher alcohol and ester functional groups, cyclic compounds but also from various functional groups.
As hidrotalcitas sÃo uma classe de hidrÃxidos duplos lamelares com importantes propriedades fÃsico-quÃmicas. O emprego desta classe de compostos na catÃlise de reaÃÃes especÃficas requer, ainda, muitos estudos. A literatura tem explorado estes materiais na catÃlise das reaÃÃes com glicerol em fase lÃquida, principalmente, em reaÃÃes de hidrogenÃlise. As reaÃÃes em fase gasosa com glicerol normalmente fazem uso de catalisadores Ãcidos, de modo. Deste modo, tanto as reaÃÃes em fase lÃquida envolvendo catalisadores derivados da hidrotalcita como reaÃÃes em fase gasosa envolvendo catalisadores bÃsicos requerem maiores estudos. Desenvolveu-se um estudo com vistas a elucidaÃÃo dos efeitos combinados de sÃtios catalÃticos bÃsicos (MgO e Ãxidos de alumÃnio amorfo) e desidrogenante (Ãxidos derivados do cobre) na reaÃÃo de hidrogenÃlise. Os materiais empregados foram Ãxidos derivados da hidrotalcita, e Ãxidos derivados contendo em sua composiÃÃo 2,5% cobre (proporÃÃo molar) em relaÃÃo aos metais da rede hidrotalcita (Mg e Al). Os resultados obtidos para a fase gasosa evidenciam uma inter-relaÃÃo entre os sÃtios e os produtos majoritÃrios da reaÃÃo, acetol e acroleina. Determinou-se condiÃÃes em que um ou outro produto à mais favorecido, com conversÃes que podem chegar a mais de 90% e seletividades que superam 99%. Em fase lÃquida esta inter-relaÃÃo à mais difÃcil de ser evidenciada, dadas as complicaÃÃes originadas pelo maior tempo de contato entre catalisador e reagentes a tal ponto dos produtos majoritÃrios verificados na reaÃÃo fase gasosa figurarem como intermediÃrios da reaÃÃo em fase lÃquida. Na fase lÃquida, predominam compostos de maior cadeia carbÃnica dos grupos funcionais Ãlcool e Ãster, mas tambÃm compostos cÃclicos de grupos funcionais diversos.

We systematically studied the preparation method of magnesium oxide as cheap heterogeneous basic catalysts, and found a very simple method to obtain MgO with high surface area and high catalytic activity. Furthermore, the structure of MgO was characterized using many techniques, such as BET, TGA, XRD and SEM. The relationship of catalytic activity and structure of MgO has been investigated in detail. At last, the obtained MgO was used in the liquid phase reactions, including Meerwein-Pondorf-Verley reaction, Michael addition, Knoevenagel condensation, transesterification of vegetable oil to biodiesel and synthesis of P-Keto 1,3-dithianes. The prepared magnesium oxide catalyst was used in the liquid phase Meerwein-Pondorf-Verley reaction of benzaldehyde with alcohol. Effect of preparation method on the catalytic activity and structure of MgO has been investigated in detail. The experimental result showed that the optimal calcination temperature was 450 °C. Lithium supported magnesium oxide was also studied. Magnesium oxide obtained using a novel but simple procedure was systematically investigated as a heterogeneous base catalyst for the Michael addition and Knoevenagel condensation. The activity of MgO was studied in detail, together with the effects of solvent and of substrate on the catalytic activity for each type of reaction. A key finding is that the formation of enols affected the activity of MgO. The preparation method and activity of MgO was determined and compared with CaO. MgO was used for the first time as a heterogeneous basic catalyst to synthesis P-keto-1,3-dithianes from conjugated ynones and ynoates. It was found that MgO is an active catalyst with activity better than or comparable with previously identified homogeneous or heterogeneous catalysts for this reaction. The effect of preparation methods on the activity of MgO is described. Transesterification of vegetable oil to biodiesel with MgO as catalyst was studied at 60 °C and 200 °C, respectively. Effect of methanol-to-oil molar ratio, catalyst loading, reaction temperature and calcination temperature was investigated. 90% yield can be obtained at 60 °C for 3h, and 80% at 200 °C for 15min. The results showed that the prepared MgO was active for the synthesis of biodiesel.

Dans ce travail, nous présentons une étude originale de l'utilisation des catalyseurs basiques solides dans la réaction de transestérification des acrylates. La réaction de l'acrylate d'éthyle avec le n-hexanol a été choisie comme réaction modèle. Les catalyseurs employés, à base d'alumines modifiées par des ions alcalins, alcalino-terreux ou fluorures, se sont avérés être actifs et sélectifs dans la réaction de transestérification, réalisée en conditions douces, sans solvant, en utilisant un rapport stoéchiométrique des réactifs. Les réactions secondaires ont été identifiées comme étant des réactions d'addition de Michael. Nous avons mis en évidence que la réaction de transestérification se produit sur des sites basiques faibles, le catalyseur Ca(NO3)2/ γ-Al2O3 ayant montré la sélectivité la plus élevée en acrylate d'hexyle (> 90%) pour une conversion supérieure à 60%. L'étude du recyclage du catalyseur nous a permis de déterminer les facteurs les plus influents tels que le contact du catalyseur avec le CO2 et l'eau ainsi que la teneur en fer de l'alumine employée comme support. Ces facteurs sont déterminants pour le recyclage du catalyseur, qui peut alors être recyclé jusqu'à 4 fois dans la réaction de transesterification de l'acrylate d'éthyle par le n-hexanol sans observer de changements significatifs de la conversion et de la sélectivité
We present an original study of the use of solid basic catalysts in the transesterification reaction of acrylates. The reaction of ethyl acrylate with n-hexanol was chosen as model reaction. The catalysts employed, based on alumina modified with alkalin, alkalin earth, and fluoride ions were shown to be active and selective for the reaction of transesterification reaction carried out under mild conditions, without solvent, using a stoechiometric amount of reactants . The secondary reactions were identified as Michael addition reactions. We demonstrated that the transesterification reaction occurs on weak basic sites, the catalyst Ca (NO3)2 /γ-Al2O3 has shown the highest selectivity in the hexyl acrylate (> 90%) for conversion greater than 60%. The study of the catalyst recycling allowed to determine the most influential factors such as the catalysts contact between CO2 and water as well as the iron content of the alumina support. These factors are critical to the success of the catalyst recycling, which was done four times in the reaction of transesterification of ethyl acrylate with n-hexanol without observing significant changes in the conversion and selectivity

Philosophiae Doctor - PhD
Magnesium hydride has long been regarded as a promising candidate for lightweight hydrogen storage applications, owing to reasonably high theoretical capacity (7.6 wt. %). It is burdened by slow absorption/desorption kinetics which has been the target for improvement of many research groups over the years. Nanostructured MgH2 prepared by high energy reactive ball milling (HRBM) of Mg under hydrogen atmosphere with the addition of V or Ti results in modified MgH2 that demonstrates superior hydrogenation/dehydrogenation kinetics without a crippling compromise in storage capacity. Mg – FeV nanocomposites prepared via ball milling of Mg and FeV raw materials demonstrated up to 96.4% of the theoretical storage capacity and comparable kinetics to Mg - V prepared via the same method using pure refined V (which is far costlier than FeV). In both cases, the hydrogenation/dehydrogenation kinetics was much improved than pure Mg alone, as evidenced by faster hydrogenation times. In terms of cyclic stability, Mg – 10FeV demonstrated improvement over pure Mg with final absorption and desorption capacities of 4.93 ± 0.02 wt. % and 4.82 ± 0.02 wt. % respectively over 30 cycles. When compared against Mg – V, Mg – FeV showed slightly inferior improvements, attributed to incomplete hydrogenation of V in the presence of Fe. However, they share similar crystalline BCC, BCT – V2H and FCC - VH phases with the size of less than 10 nm and demonstrated the same behaviour at high temperatures; at temperatures approaching 400 °C, particle sintering became an issue for both nanocomposites resulting in a drop in absorption capacity even in the first cycle. The further inclusion of carbonaceous species showed several effects, one of which was an improvement in hydrogen uptake speed as well as kinetics for the addition of 5 wt. % activated carbon. For the sample with 5 wt. % graphite, the appearance of an initial incubation period of up to 60 minutes was noted, presumably corresponding to the duration of time when the carbon was sheared and crushed before hydrogenation commences.

Caspase-3 is a cysteine protease that hydrolyzes diverse intracellular proteins during programmed cell death (known as apoptosis). It has been a popular target for drug design against abnormal cell death for more than a decade. No approved caspase based drug, however, is available so far. Therefore, structural insights about the substrate recognition of caspase-3 are needed for the future development of caspase-3 based inhibitors and drugs. In this study, crystal structures of recombinant caspase-3 in complex with seven substrate analog inhibitors, including acetyl (Ac)-DEVD-aldehyde (Cho), Ac-DMQD-Cho, Ac-IEPD-Cho, Ac-YVAD-Cho, Ac-WEHD-Cho, Ac-VDVAD-Cho, and tert-butoxycarbonyl (Boc)-D-fluoromethylketone (Fmk), have been analyzed in combination with enzyme kinetic data and computational models. Seven crystal structures were determined at resolutions of 1.7-2.6Å. The binding conformation of each inhibitor residue at P1-P4 position was analyzed. The negative P1 aspartic acid side chain is exclusively required by the positive S1 pocket of caspase-3. Small hydrophobic P2 residues are preferred by the nonpolar S2 pocket formed by Y204, W206, and F256. Although hydrophilic residues at P3 position tend to fit better, hydrophobic residues also can be accommodated by the plastic S3 pocket. Two substrate binding sites were found in the S4 pocket, one formed by main chain atoms of F250 and side chain atoms of N208 and the other formed by aromatic side chains of W206 and W214. These two binding sites are responsible for the binding of hydrophilic and hydrophobic P4 residues, respectively. Furthermore, the S5 subsite of caspase-3 formed by side chains of F250 and F252 was discovered. It stabilizes hydrophobic P5 residues on the substrates by an induced fit mechanism. Computational studies were performed to help improve prediction of protein structures and protein-ligand interactions. Based on the Morse’s function, a novel potential function with only three adjustable parameters per residue pair was developed, which will significantly increase the efficiency of protein structure prediction and molecular mechanics. Altogether, our studies have provided valuable information for the future caspase-3 based drug development.

Nature’s biodiversity is complex and filled with beauty and wonder which are all observable on the macroscopic scale. This exquisiteness of nature’s intricacies are mirrored on the molecular level such that substances, large or small, are assembled to serve as signaling molecules, protective agents, and fundamental composites of higher-order frameworks for the operation and survival of life. Over the years, chemists have isolated and synthesized these molecules, known as natural products, to understand and evaluate their functions in biology and potential for medicinal applications. Although bioactive natural products demonstrate medicinal promise, poor pharmacological effects require further derivatization because semisynthesis is not sufficient to refine adverse pharmacokinetics. For some active molecules, isolation results in poor yields. In addition to small quantity isolation, many natural products, reflecting the immense complexity of biology itself, pose difficult synthetic challenges to organic chemists because of skeletal heterogeneity, stereochemical complexity, and substitution divergence. As a result of these synthetic obstacles to natural product utilization, improvements are needed in current chemical approaches, and new innovative methodologies for synthesis and chemical space exploration are necessary. Pharmaceutically relevant frameworks, natural products, and synthetic biologically active molecules are comprised of polycarbocyclic and heterocyclic scaffolds. Traditionally, cycloadditions, transannular transformations, and annulation reactions serve as powerful methods for polycyclic formation. In order to assemble diverse polycycles, donor-acceptor cyclopropanes are useful, versatile synthetic equivalents for C-C bond formations. By taking advantage of the strain within these unique, polarized systems, differing molecular architectures can be accessed directly to perform contemporary organic synthesis. Moreover, the donor-acceptor cyclopropanes initially utilized in these studies provided a fundamental basis for new methods to synthesize other relevant scaffolds. Unique, efficient, Lewis acid-catalyzed intramolecular cyclization strategies for the construction of functionalized polycycles using Friedel-Crafts-type alkylation sequences are presented to expand the reaction repertoire of the molecular architect. Generally, products were formed from commercially-available starting materials in high yields with broad scope. The methodologies were demonstrated to be modular, operationally simple, and amenable to different substitution patterns and functional groups to afford tetrahydroindolizines, heteroaromatic cyclohexenones, hydropyrido[1,2-a]indoles, pyrrolo[1,2-a]indoles, pyrrolo[3,2,1-ij]quinolines, pyrrolizines, and tetrahydrobenzo[ij]quinolizines. To demonstrate the utility of the methodologies devised, progress toward, (±)-rhazinicine, a natural product, is discussed. This dissertation is organized into six chapters: (1) an introduction, paradoxical stress and molecular strain’s utility in synthesis; (2) annulation reactions for the formation of heteroaromatic cyclohexenones; (3) hydropyrido[1,2-a]indole formation via an In(III)-catalyzed cyclopropane ring-opening/Friedel-Crafts alkylation sequence; (4) tetrahydroindolizine formation and progress toward the total synthesis of (±)-rhazinicine (5) pyrrolo[1,2-a]indole synthesis using a Michael-type Friedel-Crafts cyclization approach; and (6) a versatile protocol for the intramolecular formation of functionalized pyrrolo[3,2,1-ij]quinolines.

Ubiquitination is a post-translational modification of proteins with broad regulatory roles across cellular biology. This process involves the addition of ubiquitin molecules on target proteins, altering their cellular role and properties. Ubiquitination is performed by an enzymatic cascade consisting of three enzymes: ubiquitin activating enzymes (E1), ubiquitin conjugating enzymes (E2) and ubiquitin ligases (E3). The tripartite motif (TRIM) family of proteins constitutes one of the largest subfamilies of RING E3 ligases and the majority of them are contributing to the regulation of innate immune responses. They are characterized by a conserved tripartite motif in their N-terminal region which comprises a RING domain, one or two B-box domains and a coiled-coil region. Self-association is believed to be crucial for catalytic activity of TRIM proteins, however, the precise molecular mechanism underlying this observation remains elusive. The work presented in this thesis provides insights into the E3 ligase function of TRIM25 and shows how its oligomeric state is linked to its catalytic activity. The crystal structure of a complex between the TRIM25 RING domain and a ubiquitin-loaded E2 identifies the structural and mechanistic features that promote activation of E2~Ub allowing us to propose a model for the regulation of activity in the full-length protein. In the second part of this thesis, the molecular details of Influenza A NS1-mediated TRIM25 inhibition are presented. The crystal structures of NS1 bound to TRIM25 along with biochemical analysis allowed us to identify the interacting domains and propose a model for the inhibition of substrate ubiquitination during viral infection. The results of this project extend our understanding of the mechanism, structure and regulation of TRIM E3 ligases and their substrates, leading to increased chances of targeting specific steps of the ubiquitination pathway during disease.

Thesis (M.S.)--Southern Illinois University Carbondale, 2007.
"Department of Mechanical Engineering and Energy Processes." Includes bibliographical references (leaves 53-54). Also available online.

Thesis (Ph. D.)--Chemistry and Biochemistry, Georgia Institute of Technology, 2006.
Dr. Allen M. Orville, Committee Chair ; Dr. Loren D. Williams, Committee Member ; Dr. Donald F. Doyle, Committee Member ; Dr. Dale E. Edmondson, Committee Member ; Dr. Giovanni Gadda, Committee Member.

Thesis (MEng)--Stellenbosch University, 2014.
ENGLISH ABSTRACT: The enactment of the new Constitution of South Africa, 1996, gave prominence to the trans-formation of local government in South Africa. Rooted in the Constitution, the Municipal Systems Act, 2000, and the Municipal Structures Act, 1998, guide municipalities towards establishing structured performance management practices. As part of a comprehensive legislative framework for local government, these acts moreover state the functions of mu-nicipalities that include the delivery of basic municipal services. These services include amongst other, water provision, refuse removal, sanitation, electricity provision, municipal roads as well as stormwater management. Despite a range of statutory provisions, policy instruments and capacity improvement initiatives with a view to provide a democratic, participative, responsive, effective and efficient local sphere of government, South African municipalities, in general, continue to fail in eradicating service delivery backlogs. This is, at least partially, the result of the policies and practices of the apartheid era. Apart from eradicating backlogs, non-sustaining service delivery to communities has become a noticeable phenomenon. As a result, in 2012 the highest number of service delivery protests over the past decade occurred. The underperformance of municipalities can be linked to insufficient organisational capacity. This multidimensional concept consists of individual, institutional and environmental capacity. This study views capacity building as a key enabler for municipal performance improvement. Relating to this, capacity assessment is the first and foremost component of capacity building. Hence, it can be assumed that a correlation exists between municipalities’ service delivery performance and the degree to which municipalities are aware of its capacity to fulfil its service delivery mandate. Municipalities are mandated by the Municipal Systems Act, 2000 to perform internal capacity assessments when a new or reviewed Integrated Development Plan (IDP) is considered, and also when outsourcing of municipal services is considered. Besides this the Municipal Demarcation Board (MDB) is mandated by the Municipal Structures Act, 1998, to perform annual municipal capacity assessments. Though criticised for its untimeliness, narrow approach and inconsistency, the MDB municipal capacity assessment generates valuable insight. This is widely used by provincial governments, municipalities and private parties for policy formulation, strategic decision-making and capacity building initiatives. This exemplifies that if accurate municipal capacity data can frequently be attained, the effects on service delivery improvement initiatives can be profound. This research study aims to make a contribution in formulating solutions for needs that currently exist in this regard in South Africa. The focus of this study is the development of both a municipal capacity assessment frame-work and a subjective municipal capacity self-assessment model (SMCSAM), a software tool built in Microsoft’s Visual Basic for Applications (VBA) for engineering services at municipalities. The framework for municipal capacity assessment comprises of fifteen elements of capacity and eighteen service delivery phases. A third dimension of the framework exists in recognition of the six basic municipal services. This framework accordingly implements the matrix-method. SMCSAM implements the consolidated framework based on statements to be rated by the municipality according to their reality. SMCSAM allows the municipality to allocate weights to each of the fifteen elements of overall organisational capacity through the use of a Fuzzy Logic Hierarchical Analytical Process. Consequently, ratings of the statements are weighed and illustrated through two interactive user-interfaces which allow the municipality to instantly identify capacity strengths and weaknesses. To achieve this, assessment results are illustrated using colour-coding and related spider-diagrams. SMCSAM was implemented at Drakenstein Municipality and demonstrated to academics as well as experts in the public and private sector for validation purposes. Its results proved to be accurate and applicably related to the performance of this municipality. Through its implementation and validation, SMCSAM proved to be a valuable, understandable and practical solution to a noteworthy problem at municipalities in South Africa. In doing so, SMCSAM significantly contribute to research in the field of engineering management.
AFRIKAANSE OPSOMMING: Die aanvaarding van die nuwe Grondwet van Suid-Afrika, 1996 het grootliks aanleiding gegee tot die transformasie van plaaslike regering in Suid-Afrika. Munisipaliteite word deur die Wet op Munisipale Stelsels, 2000, en die Wet op Munisipale Strukture, 1998, begelei in die implementering van gestruktureerde prestasiebestuur praktyke. As deel van 'n omvattende wetgewende raamwerk, definieer hierdie twee wette ook die funksies van munisipaliteite, wat die lewering van basiese dienste insluit. Basiese dienste sluit onder andere watervoorsiening, vullisverwydering, sanitasie, elektrisiteitsvoorsiening, munisipale paaie en stormwaterbestuur in. Ten spyte van dié statutêre voorsienings, gepaardgaande beleidmaatreëls en inisiatiewe vir kapasiteitsverbetering met die doel om ʼn demokratiese, deelnemende, responsiewe, effektiewe en doeltreffende plaaslike sfeer van regering daar te stel, misluk baie munisipaliteite in Suid-Afrika in hul pogings om jarelange diensleweringsagterstande uit te wis. Hierdie agterstande is gedeeltelike die gevolg van die beleide en praktyke van die apartheidsera. Afgesien van die vertraagde uitwissing van agterstande, word munisipaliteite se onvermoë om effektiewe dienslewering aan gemeenskappe vol te hou, ook geïdentifiseer as ʼn probleemarea. As ʼn gevolg hiervan, het die jaarlikse hoeveelheid diensleweringproteste in 2012 ʼn nuwe hoogtepunt bereik. Die onvermoë van munisipaliteite om hul diensleweringsmandaat uit te voer kan grootliks toegeskryf word aan onvoldoende organisatoriese kapasiteit. Dié multidimensionele konsep bestaan uit individuele-, institusionele- en omgewingskapasiteit. Hierdie studie beskou kapasiteitsontwikkeling as ʼn fundamentele dryfkrag vir beter munisipale dienslewering, terwyl die assessering van munisipale kapasiteit die eerste en belangrikste fase van kapasiteitsontwikkeling is. Dit kan dus aanvaar word dat daar ʼn korrelasie bestaan tussen ʼn munisipaliteit se diensleweringsprestasie en die mate waartoe die munisipaliteit bewus is van sy kapasiteit om sy diensleweringsmandate na te kom. Munisipaliteite word deur die Wet op Munisipale Stelsels, 2000, verplig om ʼn interne kapasiteits-assessering te doen wanneer ʼn nuwe of hersiende Geïntegreerde Ontwikkelingsplan (GOP) oorweeg word of wanneer daar besluit moet word oor die uitkontraktering van munisipale dienslewering. Terselfdertyd word die Munisipale Afbakeningsraad (MAR) deur die Wet op Munisipale Strukture, 1998, verplig om jaarlikse munisipale kapasiteits-assesserings uit te voer. Alhoewel die MAR se munisipale kapasiteits-assessering gekritiseer word vir die ontydigheid, inkonsekwentheid en beperkte aanslag daarvan, word die resultate van hierdie assessering aangewend deur provinsiale regerings, munisipaliteite asook ander rolspelers in die publieke- en privaatsektor vir die doel om beleid te formuleer, strategiese besluite te neem en kapasiteit te bou. Dit dui daarop dat wanneer akkurate data van munisipale kapasiteit gereeld versamel word, dit grootliks dienslewering verbeteringsinisiatiewe kan aanhelp. Die studie ondersoek ʼn innoverende metode vir die selfassessering van munisipale kapasiteit. Die fokus van die studie is die ontwikkeling van ʼn gekonsolideerde munisipale kapasiteits-assesseringsraamwerk en ʼn geassosieerde subjektiewe munisipale kapasiteit selfassesseringsmodel (SMCSAM), ʼn sagtewarepakket wat geprogrammeer is in Microsoft se Visual Basic for Applications (VBA). Die raamwerk bestaan uit vyftien elemente van kapasiteit en agtien diensleweringsfases. ʼn Derde dimensie van die raamwerk bestaan in die erkenning van die voorgenoemde ses basiese dienste. Hierdie raamwerk implementeer die matriksmetode dienooreenkomstig. SMCSAM implementeer die gekonsolideerde raamwerk gebaseer op stellings wat gegradeer moet word deur munisipaliteite binne die konteks van hul eie realiteit. SMCSAM laat munisipaliteite toe om gewigte te koppel aan elkeen van die vyftien elemente van kapasiteit deur middel van ʼn Fuzzy Logic Hiërargiese Ontledingsproses. Dit gebruik twee interaktiewe gebruikerskoppelvlakke wat munisipaliteite toelaat om vinnig die sterk- en swakpunte van hul organisatoriese kapasiteit te identifiseer. Hierdie resultate word aangedui deur middel van grafieke en kleur-kodering. SMCSAM is getoets by die Drakenstein Munisipaliteit en gedemonstreer aan akademici en deskundiges in die privaat en publieke sektor. Die resultate van die assessering dui op ʼn realistiese verwantskap tussen die munisipaliteit se organisatoriese kapasiteit en diensleweringsprestasie. Deur die implementering en validasie van SMCSAM, is dit bewys dat dié model ʼn waardevolle, verstaanbare en ʼn praktiese oplossing bied vir ʼn werklike probleem by munisipaliteite in Suid-Afrika. Sodoende, maak die model ʼn betekenisvolle bydra tot die navorsingsveld van ingenieursbestuur.

Lipoxygenases (LOX) catalyze regio- and stereospecific oxygenation of polyunsaturated fatty acids to hydroperoxides. These hydroperoxides are further metabolized to leukotrienes and lipoxins in mammals, and are involved in asthma and inflammation. LOX of animals and plants contain iron as catalytic metal (FeLOX). Filamentous fungi use both FeLOX, and manganese containing LOX (MnLOX). The role of LOX in fungi is still not known. This thesis focuses on expression of novel MnLOX, analyses of their reaction mechanism and products by HPLC-MS/MS, protein crystallization and analysis of the first MnLOX structure.   MnLOX from G. graminis, M. salvinii, M. oryzae, F. oxysporum and C. gloeosporioides were expressed in Pichia pastoris, purified and characterized by HPLC-MS/MS. All MnLOX catalyzes suprafacial hydrogen abstraction and oxygen insertion. Replacement of one Ile to Phe in the active site of MnLOX of G. graminis could switch the mechanism from suprafacial to mainly antarafacial. MnLOX of F. oxysporum was interesting since it catalyzes oxygenation of linoleic acid to 11R- instead of the more common 11S-hydroperoxides. This feature could be attributed to a single Ser/Phe exchange in the active site.   We found that Gg-MnLOX utilizes hydrogen tunneling in the reaction mechanism, but was slightly more temperature dependent than soybean FeLOX. It is an intriguing question why some fungal LOX use manganese and not iron as catalytic metal and whether the large redox potential of Mn2+/Mn3+ (1.5 V) can be tuned close to that of Fe2+/Fe3+ (0.77 V) for redox cycling and catalysis. We present crystallization conditions for two MnLOX, and the 2.07 Å crystal structure of MnLOX from M. oryzae, solved using sulfur and manganese single anomalous dispersion (SAD). The structure reveals a similar metal coordinating sphere as FeLOX but the metal ligand Asn473 was positioned on a short loop instead of a helix and formed interactions with a conserved Gln. This feature could be essential for the use of manganese as catalytic metal in LOX. We found three Phe residues that likely facilitate the suprafacial hydrogen abstraction and oxygen insertion for MnLOX. These findings provide new insight into the unique reaction mechanism of MnLOX.

Orientador: Ricardo Alan Verdu Ramos
Banca: Antonio João Diniz
Banca: Marcio Higa
Resumo: Neste trabalho são analisadas técnicas de produção do biodiesel a partir do óleo residual reciclado, visando a diversificação da matriz energética brasileira e minimização dos impactos ambientas decorrentes do descarte inadequado desses óleos. Antes do início da produção de biodiesel é necessária a realização de um pré-tratamento deste óleo, o que envolve processos de filtragem, secagem e determinação do teor de acidez, seguida de neutralização, pois de acordo com a porcentagem de ácidos graxos livres presentes na matéria-prima é que os métodos para obtenção dos ésteres são adotados. Primeiramente, foram realizados testes laboratoriais em pequena escala para produção de biodiesel, utilizando como matérias prima o óleo residual reciclado e o óleo de soja degomado para efeito comparativo, tendo sido utilizado hidróxido de sódio como catalisador e experimentadas as rotas metílica e etílica, não tendo sido obtidos resultados satisfatórios neste último caso. Em seguida, a produção foi expandida para uma escala semi-piloto, através da utilização de um reator com capacidade de produzir entre 75 e 80 litros de biodiesel por batelada, sendo neste caso utilizado apenas óleo residual reciclado e processo de transesterificação através da rota metílica, tendo o hidróxido de sódio como catalisador. Depois disso, foi feita a caracterização básica do biodiesel produzido, utilizando-se os equipamentos disponíveis, e foram realizados testes comparativos com outros tipos de biodiesel (Comercial, Vegetal e Animal) e frações de misturas (B25, B50, B75 e B100), tendo como base o biodiesel comercial (B5). Por fim, foram feitos testes com esses combustíveis em um moto-gerador diesel de 6 kVA, variando-se a carga de 0 a 3 kW e determinando-se o consumo específico e a temperatura dos gases de exaustão... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: This study analyzes the technical production of biodiesel from waste oil recycling, aimed at diversifying the Brazilian energy matrix and minimizing the environmental impacts of inadequate disposal of waste oils. Before the production of biodiesel it is necessary to perform a previous treatment of this oil, which involves processes of filtration, drying and determination of acidity, followed by neutralization, because according to the percentage of free fatty acids present in the raw material is that the methods for obtaining the esters are defined. Firstly, laboratory tests were performed on a small scale biodiesel production using raw materials like soybean oil and recycle waste soybean oil for comparison, having been used sodium hydroxide as catalyst and tested methyl and ethyl routes, being no obtained satisfactory results in this last case. Then, the production was expanded to a semi-pilot scale, using a reactor that can produces between 75 and 80 liters of biodiesel per batch, being in which case only used recycle waste oil and the transesterification process using methanol route, with sodium hydroxide as catalyst. After that, a basic characterization of biodiesel had been done, using equipment available, and were conducted comparative tests with other types of biodiesel (commercial, vegetable and animal) and fractions of blends (B25, B50, B75 and B100), with commercial biodiesel like base of comparison (B5). Finally, tests were performed with these fuels in a 6 kVA diesel generator set, varying a resistive load from 0 to 3 kW and determining the specific consumption and temperature of the exhaust gases. Analyzing the results, it was verified that the physical and chemical properties measured are within acceptable limits, with density between 0,871 and 0,910 g/ml, viscosity between 3,9 and 6,1 cSt and flash point between 51 and 183°C,... (Complete abstract click electronic access below)
Mestre

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Universidade Federal de Minas Gerais
The use of zeolites in basic catalysis is small, especially when compared to the numerous applications of material in their acid form. Inside this context, are even smaller the number of studies on the use of as-synthesized zeolites as basic catalysts. Zeolites are crystalline hydrated aluminosilicates that have a pores size well-defined. Many of zeolite structures need organic compounds to be synthesized, these compounds are called structure directing agents. Zeolites containing organic cations (as-synthesized) have basic properties and can be used as catalysts in reactions that require this type of catalytic site. In this work were investigated three zeolites structures widely studied in the literature, BEA, MFI and MTW. Zeolites were synthesized with different compositions (ratio Si/Al) in the reaction mixture. Addition to the conventional synthesis were performed modifications using an organosilane (TPOAC - trimethoxysilyl-propyl-octadecylammonio chloride) in the synthesis of structures MFI and MTW. Were obtained, for the three structures, samples with different Si/Al ratios, some of them containing organosilane. The samples were characterized and used as catalysts in the Knoevenagel condensation. For all samples the increase of the Si/Al ratio increased the number of species [≡Si O ][TEA+]. The characterization and catalytic conversion show that for BEA zeolite only one portion of the species [≡Si O ][TEA+] were available for the reaction. The samples modified with organosilane (TPOAC) were the most active, especially with MTW structure. This increased activity is related to the modification that the organosilane promoted on the surface of the particles. The addition of organosilane favored the increase of the Si/Al ratio on the surface and this may be related to better conversion results. In this work, we propose new efficient catalysts, with zeolitic structure, for reactions involving basic sites.
O uso de zeólitas em catálise básica ainda é muito pequeno, principalmente quando comparado às inúmeras aplicações de material em sua forma ácida. Dentro desse contexto, é menor ainda o número de estudos sobre a utilização de zeólitas tal como sintetizadas como catalisadores básicos. Zeólitas são aluminosilicatos hidratados cristalinos que possuem um tamanho de poros muito bem definidos. Muitas das estruturas zeolíticas precisam de compostos orgânicos para serem sintetizadas, esses compostos são chamados de direcionadores de estrutura. Zeólitas contendo cátions orgânicos (tal como sintetizadas) possuem propriedades básicas e podem ser usadas como catalisadores em reação que necessitam esse tipo de sítio catalítico. Nesse trabalho foram investigadas 3 estruturas zeólitas bastante estudadas na literatura, BEA, MFI e MTW. As zeólitas foram sintetizadas com diferentes composições (razão Si/Al) na mistura reacional. Além da síntese convencional foram realizadas também modificações usando um organossilano (TPOAC Cloreto de Trimetoxisilil-propil-octadecilamônio) na síntese das estruturas MFI e MTW. Foram obtidas, para as 3 estruturas, amostras com diferentes razões Si/Al, algumas delas contendo organossilano. As amostras foram caraterizadas e usadas como catalisadores na reação de condensação de Knoevenagel. Para todas as amostras o aumento da razão Si/Al levou ao aumento da quantidade das espécies [≡Si O ][TEA+]. As caracterizações e os resultados de conversão catalítica mostram que para a zeólita BEA apenas parte das espécies [≡Si O ][TEA+] estavam na superfície disponíveis para a reação. As amostras modificadas com organossilano (TPOAC) foram as mais ativas, principalmente as com estrutura MTW. Essa maior atividade está relacionada a modificação que o organossilano promoveu na superfície das partículas. A adição de organossilano favoreceu o aumento da razão Si/Al na superfície e isso pode estar relacionado aos melhores resultados de conversão. Nesse trabalho, propomos novos catalisadores eficientes, a base de zeólitas, para reações que envolvam sítios básicos.

Not all documents are records. One of the central concerns of contemporary governance is the reduced or complete lack of accountability among public officials when rendering public services. In the absence of accountability and records, corruption thrives. This research examines the relationship that exists between transparency, accountability and record keeping in order to find the effect that records has; in terms of producing positive audit outcomes and in eliminating corrupt activities by public official/s. Since the transition to democracy in South Africa, the new constitution demands transparency and accountability on matters of governance supported with available information (records). Various pieces of legislation in South Africa are available in support of timely, accessible and accurate information in pursuit of official duties. The difficulty in ensuring an effective record keeping creates an opportunity for governance, transparency and accountability to fail. The essence of this research undertaking was motivated by the fact that, absence of records (which has a negative effect in achieving clean audits) renders governance chaotic and infringes on the democratic principles enshrined in the Constitution such as accountability and transparency. The purpose of the study was to investigate the practice of record keeping in the Eastern Cape Provincial Department of Basic Education (ECDoE) in ensuring accountability and transparency. This research undertaking was guided by the following three research questions: (1) what is the legal/normative framework that governs record keeping in South African public service? (2) How does ECDoE practice record-keeping in ensuring accountability and transparency? And (3) how does the practice of ECDoE’s record-keeping compare with the requirements of the legal/normative framework? After all the gathering of information from different sources, it is therefore recommended that the ECDoE send its employees for records management courses and there must be strict adherence to legislation and recommendations made by the Auditor General in his last audit report for the department. During the conduct of this research undertaking, these are the findings that emerged from the study: at the ECDoE (1) There is no adequate training provided to employees in record keeping. (2) There are ineffective internal control systems. (3) There is no risk management contingency plan. (4) There is no proper record keeping. (5) There is non-compliance with legislation by officials. (6) There is no strong or effective leadership. (7) There is shortage of staff and qualified personnel. (8) Lack of commitment to excel. (9) No significant corrective action undertaken to eliminate past inaccuracies. (10) There is absence of following up on recommendations made by the external audit. Lastly, the researcher accepts the arguments raised by the different authors about record keeping, transparency and accountability in that: there can be no accountable and transparent government without an effective record-keeping in place. Records are vital sources of evidence admissible to any institution be it a court of law or standing committees should clarity be required.

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Neste trabalho são analisadas técnicas de produção do biodiesel a partir do óleo residual reciclado, visando a diversificação da matriz energética brasileira e minimização dos impactos ambientas decorrentes do descarte inadequado desses óleos. Antes do início da produção de biodiesel é necessária a realização de um pré-tratamento deste óleo, o que envolve processos de filtragem, secagem e determinação do teor de acidez, seguida de neutralização, pois de acordo com a porcentagem de ácidos graxos livres presentes na matéria-prima é que os métodos para obtenção dos ésteres são adotados. Primeiramente, foram realizados testes laboratoriais em pequena escala para produção de biodiesel, utilizando como matérias prima o óleo residual reciclado e o óleo de soja degomado para efeito comparativo, tendo sido utilizado hidróxido de sódio como catalisador e experimentadas as rotas metílica e etílica, não tendo sido obtidos resultados satisfatórios neste último caso. Em seguida, a produção foi expandida para uma escala semi-piloto, através da utilização de um reator com capacidade de produzir entre 75 e 80 litros de biodiesel por batelada, sendo neste caso utilizado apenas óleo residual reciclado e processo de transesterificação através da rota metílica, tendo o hidróxido de sódio como catalisador. Depois disso, foi feita a caracterização básica do biodiesel produzido, utilizando-se os equipamentos disponíveis, e foram realizados testes comparativos com outros tipos de biodiesel (Comercial, Vegetal e Animal) e frações de misturas (B25, B50, B75 e B100), tendo como base o biodiesel comercial (B5). Por fim, foram feitos testes com esses combustíveis em um moto-gerador diesel de 6 kVA, variando-se a carga de 0 a 3 kW e determinando-se o consumo específico e a temperatura dos gases de exaustão...
This study analyzes the technical production of biodiesel from waste oil recycling, aimed at diversifying the Brazilian energy matrix and minimizing the environmental impacts of inadequate disposal of waste oils. Before the production of biodiesel it is necessary to perform a previous treatment of this oil, which involves processes of filtration, drying and determination of acidity, followed by neutralization, because according to the percentage of free fatty acids present in the raw material is that the methods for obtaining the esters are defined. Firstly, laboratory tests were performed on a small scale biodiesel production using raw materials like soybean oil and recycle waste soybean oil for comparison, having been used sodium hydroxide as catalyst and tested methyl and ethyl routes, being no obtained satisfactory results in this last case. Then, the production was expanded to a semi-pilot scale, using a reactor that can produces between 75 and 80 liters of biodiesel per batch, being in which case only used recycle waste oil and the transesterification process using methanol route, with sodium hydroxide as catalyst. After that, a basic characterization of biodiesel had been done, using equipment available, and were conducted comparative tests with other types of biodiesel (commercial, vegetable and animal) and fractions of blends (B25, B50, B75 and B100), with commercial biodiesel like base of comparison (B5). Finally, tests were performed with these fuels in a 6 kVA diesel generator set, varying a resistive load from 0 to 3 kW and determining the specific consumption and temperature of the exhaust gases. Analyzing the results, it was verified that the physical and chemical properties measured are within acceptable limits, with density between 0,871 and 0,910 g/ml, viscosity between 3,9 and 6,1 cSt and flash point between 51 and 183°C,... (Complete abstract click electronic access below)

Nesse estudo, foram preparadas bases poliméricas derivadas de 2,6-dimetilpiridinas e tereftaladeído utilizando a 2,4,6-trimetilpiridina como agente de reticulação. As resinas foram sintetizadas sob aquecimento convencional e purificadas por precipitação em metanol, apresentando rendimentos variando de 59 a 95%. Os copolímeros produzidos foram caracterizados por análise termogravimétrica (TGA), ressonância nuclear magnética de núcleo de hidrogênio (RMN-1H) e espectroscopia na região do infravermelho com técnica de ATR (FTIR - ATR), além de sua atividade básica. A capacidade catalítica do material produzido foi avaliada em reações nitroaldólicas, do tipo Henry, tanto em aquecimento convencional quanto com o uso de reator de micro-ondas. Não sendo observada atividade catalítica significativa para as resinas testadas, nestas reações. O material polimérico produzido também foi testado como suporte para cobre na catálise de reações de cicloadição heterodipolar do tipo [3+2] com benzilazida e propiolato de etila, para a formação de triazóis, processadas em reator de micro-ondas e sob aquecimento convencional. A reação mostrou-se regiosseletiva e processos de reciclo do catalisador se mostrou eficiente em reações consecutivas
In this study, polymeric bases from 2,6-dimethylpyridines and terephthaladehyde using 2,4,6-trimethylpyridine as crosslinking agent were prepared. The resins were synthesized under conventional heating, and purified by precipitation in methanol, with yields ranging 59-95%. The produced copolymers were characterized by thermogravimetric analysis (TGA), proton nuclear magnetic resonance (1H-NMR), infrared spectroscopy by attenuated total reflection (FTIR - ATR) and basic activity. The catalytic ability of the material produced was evaluated in nitroaldol reactions (Henry reactions) as both conventional heating and a microwave reactor. Catalytic activity was not observed for the tested resins in these reactions. The polymeric material produced was also tested as an activator in Heterodipolar [3 + 2] cycloaddition reactions, with benzyl azide and ethyl propiolate to the formation of triazoles, performed in microwave reactor and conventional heating. The reaction proved to be regioselective and recycling processes of the catalyst is efficient in consecutive reactions

Una de les àrees més prometedores en recerca biomèdica i farmacèutica és el disseny molecular computacional, que intenta establir relacions entre propietats físico-químiques i activitat biològica.
L'èxit d'aquestes tècniques depen críticament de la qualitat de la descripció molecular. En aquest sentit, metodologies basades en potencials d'interacció molecular (MIP) són eines útils per la comparació de compostos que presenten comportaments biològics semblants.
Aquest projecte desenvolupa eines per comparar molècules basades en la caracterització de llurs MIPs. El programa de similaritat molecular MIPsim ha estat desenvolupat i aplicat a diferents problemes biològics.
Aquesta tesi consisteix en quatre estudis científics que mostren l'ús del MIPSim en aliniament molecular, catalisi enzimàtica, en acoratge de molècules dins el lligand i en estudis 3D-QSAR.
One of the most promising areas in biomedical and pharmaceutical research is computer assisted molecular design, which tries to stablish relationships between physicochemical properties and biological activity.
The success of these techniques depends critically on the quality of the molecular description. In this sense, methodologies based on molecular interaction potentials (MIP) are useful tools for the comparison of compounds displaying related biological behaviours.
This project aims to develop tools to compare 'molecules based on the characterization 'of their MIPs. To this end, the molecular similarity program MIPSim has been further developed and applied to different biological problems.
This thesis consists on four scientific studies showing the use of MIPSim for molecular alignment, enzymatic catalysis, ligand-protein docking and 3D-QSAR analyses.

Ziel der Arbeit war es, Katalysatoren zu entwickeln, in Modellsystemen zu testen und Rückschlüsse auf deren Aktivität und Verbesserungspotential zu ziehen. Dabei standen sowohl theoretische Betrachtungen mittels quantenmechanischer Berechnungen, aber auch experimentelle Arbeiten im Mittelpunkt. Die Untersuchungen wurden an ausgewählten Beispielen der Claisen-Umlagerung und der Morita-Baylis-Hillmann-Reaktion sowie verbrückter Bis(NHC)metallkomplexe auf der Basis von Triazolen in der Mizoroki-Heck-Reaktion durchgeführt. Claisen-Umlagerung. Die Wechselwirkung zwischen Substrat und dem Katalysator sollte hierbei auf eine bidendate Ausbildung von Wasserstoffbrücken zum Substrat entsprechend dem Design nach Jørgensen[1-4] abzielen. Die Auswahl der „Organokatalysatoren“ erstreckte sich von den Thioharnstoffen, über L-Milchsäure, einem Phosphorsäure-Derivat bis hin zu 2,2,2-Trifluorethanol (TFE). Mit dem Allyl Vinyl Ether (AVE) 83 wurden die theoretischen Betrachtungen der Wechselwirkung und der sich daraus ergebende Einfluss auf die Umlagerungs-geschwindigkeit durchgeführt. Der Thioharnstoff 1 und dessen Wechselwirkung mit 83 standen dabei im Mittelpunkt der Betrachtungen. Es wurden zwei mögliche entscheidende Übergangszustände postuliert. Im Vergleich zum konkurrierenden Übergangszustand [s-cis-83b•1A]# war [s-trans-83b•1A]# in Summe bevorzugt. Gegenüber der thermischen Claisen-Umlagerung von 83 war [s-trans-83b•1A]# für ΔG#[3,3] um +3,1 Kcal mol-1 erniedrigt, was einer leichten Erhöhung der Umlagerungsgeschwindigkeit entsprach. Dies konnte durch experimentelle Untersuchungen bestätigt werden. Das Phosphorsäure-Derivat 94 war im Vergleich zur L-Milchsäure 91 besser in der Lage, die Barriere des sigmatropen Umlagerungsschrittes abzusenken. Es zeigte sich, dass die Kombination von 91 mit einem Wassermolekül 8 zu dem Komplex 92 zu einer verbesserten Stabilisierung des Übergangszustandes führte. Bei beiden Systemen wurde jedoch beobachtet, dass die Barrieren über den Gesamtverlauf der Reaktion nicht ausreichend stark abgesenkt werden konnten. Für die Berechnungen mit dem Lösungsmittel TFE wurde gezeigt, dass die Betrachtung der Wechselwirkung einzelner TFE-Moleküle mit dem Substrat 83 nicht ausreichte. Morita-Baylis-Hillman-Reaktion. Mit der Morita-Baylis-Hillman-Reaktion[5, 6] (MBH) kann im Sinne einer C-C-Verknüpfungs-reaktion neben der atomökonomischen Durchführung zusätzlich ein Stereozentrum erzeugt werden. Basierend auf den Ergebnissen von Cheng et al.[7] wurde ein systematischer Zusammenhang zwischen dem eingesetzen Vermittler/Katalysator und Ausbeute/Umsatz hergestellt. Die aus der Literatur bekannte pH-Wert-Abhängigkeit der Reaktion konnte auf einen Bereich zwischen 8 und 9 eingegrenzt werden. Unter Verwendung verschiedener Substitutionsmuster am Imidazol konnte gezeigt werden, dass 1H-substituierte Imidazole die Reaktion wesentlich langsamer als die in 1-Position unsubstituierten Imidazole vermittelten, was durch DFT-Rechnungen unterstrichen werden konnte. Im weiteren Verlauf der experimentellen Untersuchungen stellte sich heraus, dass TFE als Lösungsmittel ohne Zusatz einer weiteren Base für die Vermittlung der Reaktion gut geeignet ist. Verbrückte Bis(NHC)metallkomplexe auf der Basis von Triazolen. Die Synthese der Bis(NHC)metallkomplexe und deren Einsatz in der Katalyse wurde von Straßner et al.[8-15] sehr intensiv studiert. Teil dieser Arbeit war es, die Bandbreite der Katalysatoren zu erweitern und den Einfluss von einem Stickstoffatom im (NHC)-Rückgrat zu untersuchen. Die synthetische Zugänglichkeit der Konstitutionsisomere wurde bereits bei der Darstellung der aromatischen Triazole gewährleistet. Die sich anschließende Darstellung der entsprechenden Salze konnte für die Methoxy-Gruppe am Aromaten erfolgreich durchgeführt werden. Die Unterscheidung von Konstitutionsisomeren eines Komplexes wurde am Beispiel von 126 und 128 durchgeführt. Hierbei zeigten sich bereits im 1H-NMR-Spektrum feine Unterschiede in den Kopplungskonstanten und auch in den Signalen für die Methylenbrücke. Der tatsächliche Beweis wurde mit der 2D-Methode, der sogenannten „Heteronuclear Multiple Bond Correlation“ – HMBC, erbracht. Der Einsatz der dargestellten Palladium(II)komplexe zeigte für p-Bromacetophenon analoge Ergebnisse zu den Imidazol-Derivaten bei „gleicher“ Konzentration. Für die Komplexe, ausgehend von den asymmetrischen Triazolen (zum Beispiel 128), wurde eine erhöhte Reaktivität beobachtet. Weiterhin wurde ein signifikanter Unterschied in der Ausbeute bei Reaktionen mit p-Chloracetophenon beobachtet. Literatur. [1] D. L. Severance, W. L. Jorgensen, Journal of the American Chemical Society 1992, 114, 10966. [2] C. J. Cramer, D. G. Truhlar, Journal of the American Chemical Society 1992, 114, 8794. [3] W. L. Jorgensen, J. F. Blake, D. Lim, D. L. Severance, Journal of the Chemical Society, Faraday Transactions 1994, 90, 1727. [4] M. M. Davidson, I. H. Hillier, Journal of Physical Chemistry 1995, 99, 6748. [5] A. B. Baylis, M. E. D. Hillman, (Celanese Corp.). Application: DE DE, 1972, p. 16 pp. [6] K. Morita, Z. Suzuki, H. Hirose, Bulletin of the Chemical Society of Japan 1968, 41, 2815. [7] S. Luo, P. G. Wang, J.-P. Cheng, Journal of Organic Chemistry 2004, 69, 555. [8] S. Ahrens, A. Zeller, M. Taige, T. Strassner, Organometallics 2006, 25, 5409. [9] M. A. Taige, A. Zeller, S. Ahrens, S. Goutal, E. Herdtweck, T. Strassner, Journal of Organometallic Chemistry 2007, 692, 1519. [10] A. Meyer, T. Strassner, unpublished results 2010. [11] M. Taige, TU Dresden (Dresden), 2009. [12] S. Ahrens, E. Herdtweck, S. Goutal, T. Strassner, European Journal of Inorganic Chemistry 2006, 1268. [13] S. Ahrens, T. Strassner, Inorganica Chimica Acta 2006, 359, 4789. [14] T. Strassner, M. Muehlhofer, A. Zeller, E. Herdtweck, W. A. Herrmann, Journal of Organometallic Chemistry 2004, 689, 1418. [15] M. Muehlhofer, T. Strassner, W. A. Herrmann, Angewandte Chemie, International Edition 2002, 41, 1745.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The growing use and application of plastic materials have raised the index of residues of these materials in the great cities, mainly poli(ethylene tereftalate) (PET). Amongst the recycling techniques proposals to minimize the accumulation of these polymeric residues, the chemical recycling, has intensified the interest, on the part of the scientific community, a time that products of a high aggregate value can be achieved, that they can be used in new industrial processes. Of this form, the present work had as objective, to investigate the solubility of the PET postconsumer in different chemical agents, to promote the depolymerization chemical of the PET by hydrolysis basic and to carry preliminary study of the degradation of monomers post-hydrolysis through heterogeneous Fenton reaction using pure and Co- and Mn-doped magnetites catalysts, as source of Fe2+ in H2O2 having as molecule of reference for the study, the methylene blue (MB). The hydrolysis reaction was carried in reflux system under temperature of 110 oC for three hours using NaOH 7.5 mol L-1 as catalytic and the gotten products had been characterized by spectroscopic method in the region of the IV. The reactions of heterogeneous Fenton had been monitored by UV-visible measurements. Between the gotten results, it could be verified (i) PET solubility in phenol concentrated solution of about 40 oC; (ii) the chemical recycling of the PET presented yield of 99.72 % with recovery of monomers terephthalic acid (AT) and ethylene glycol (EG) monomers which were characterized by IV; (iii) the study of degradation of the methylene blue (MB) 20 mg L-1 was monitored by UV-visible measurements in λmax = 663 nm thus the kinetic model that better described the process was of the pseudo first-order, disclosing bigger capacity of degradation for the doped magnetite catalysers with Co and Mn, respectively; (iv) degradation of AT, was observed in λmax = 283 nm and had a similar behavior to the reference molecule; (v) the loss of the organic load of the solution afterhydrolysis of the PET was bottle was analyzed qualitatively by comparison of the spectrums obtained by FT-IV/ATR before and after of the heterogeneous Fenton reaction. Thus the results gotten in this work are considered satisfactory and promising for news studies future.
O crescente uso e aplicação de materiais plásticos tem elevado os índices de resíduos desses materiais nos lixões das grandes cidades, principalmente, o poli(tereftalato de etileno) (PET). Dentre as técnicas de reciclagem propostas para minimizar o acúmulo desses resíduos poliméricos, a reciclagem química, tem despertado maior interesse por parte da comunidade científica, uma vez que se podem obter produtos de elevado valor agregado, que podem ser utilizados em novos processos industriais. Dessa forma, o presente trabalho teve como objetivos, investigar a solubilidade do PET pós-consumo em diferentes agentes químicos, promover a despolimerização química do PET via hidrólise básica e realizar estudo preliminar da degradação dos monômeros pós-hidrólise através de reação de Fenton heterogênea utilizando catalisadores de magnetitas pura e dopadas com Co e Mn, como fonte de Fe2+em presença de H2O2, tendo como molécula de referência para o estudo, o corante azul de metileno (MB). A reação de hidrólise foi conduzida em sistema de refluxo sob temperatura de 110oC por três horas, utilizando NaOH 7,5 molL-1 como catalisador da reação e os produtos finais foram caracterizados por método espectroscópico na região de absorção do IV. As reações de Fenton heterogênea foram monitoradas através de medidas espectrofotométricas na região do UV-visível. Entre os resultados obtidos, pôde-se verificar (i) a solubilidade do PET em solução concentrada de fenol ∼ 40 oC; (ii) a reciclagem química do PET apresentou rendimento de 99,72 % com recuperação dos monômeros do ácido tereftálico (AT) e de etileno glicol (EG) que foram caracterizados por IV; (iii) o estudo da degradação da molécula de referência, MB 20 mg L -1, foi monitorado em λ = 663 nm, de maneira que o modelo cinético que melhor descreveu o processo foi o de pseudo primeira-ordem, revelando maior capacidade de degradação para os catalisadores de magnetitas dopadas com Co e Mn, respectivamente; (iv) a degradação do AT, foi observado em λ = 283 nm e teve comportamento semelhante ao da molécula de referência; (v) a perda de carga orgânica da solução pós-hidrólise do PET foi feita qualitativamente por comparação dos espectros IV/ATR das amostras de solução pós-hidrólise antes e depois de submetida á reação de Fenton. De maneira geral os resultados obtidos neste trabalho são considerados satisfatórios e promissores para outros futuros estudos.

The inhibiting and deactivating effects of basic nitrogen species present in gas oils on catalyst active sites has been well recognized over the years; however, recent studies have shown comparable inhibiting and deactivating effects exhibited by non-basic nitrogen species. A novel pre-treatment technique employing the heterogeneously cross-linked macroporous polymer poly(glycidyl methacrylate) (PGMA) as the hydrophilic support coupled with organic compound tetranitrofluorenone has shown promising results for the selective elimination of non-basic nitrogen heterocyclic species from bitumen derived heavy gas oil (HGO). Characterization techniques such as Scanning electron microscopy (SEM), low temperature N2 adsorption–desorption (BET), CHNOS elemental analysis, fourier transform infrared spectroscopy (FT-IR), epoxy content titration, and thermo gravimetry/differential thermal analyzer (TG/DTA) were employed for determining the optimum parameters during each step of the polymer synthesis. Step 1 comprised of direct polymerization of the monomers under the determined optimum conditions, with specific surface area of 34.7 m2/g and epoxy content of 5.8 wt% for the PGMA polymer support. Step 2 comprised of substitution of the epoxy ring with the acetone oxime functionality; FT-IR results indicated characteristics peaks at 1650 cm-1 which ascertained the presence of acetone oxime on the polymer, with epoxy content titration indicating a decrease of up to 33% of the epoxy content due to the substitution. Coupling of the organic compound tetranitrofluorenone with the polymer was performed in the final step, with TGA and DTG results indicating highest weight loss of approximately 126.9 μg, which signified that sample T had the greatest amount of organic compound present in comparison to the other samples (sample N to Sample S). The optimized polymer (sample T) was capable of removing nitrogen up to 6.7%, while having little to no influence on the sulphur or aromatic species. These results were in agreement with step 4 TGA analysis that showed sample T had the highest presence of the organic compound. Reusability of the polymer multiple times with consistent removal is another known advantage of such a pre-treatment technique; hence reusability studies were performed, and showed that the polymer was indeed capable of multiple uses, with consistent removal of nitrogen compounds at approximately 6.5% from fresh heavy gas oil feedstocks. Kinetic studies were performed as the final phase in order to evaluate the performance of the treated HGO in comparison to non-treated HGO. The effect of parameters such as temperature and LHSV were determined, with higher temperatures resulting in higher conversion of HDS and HDN. Similarly, as the LHSV was decreased, the conversions were increased for both HDS and HDN due to longer contact time between the feed and the catalyst. The highest obtained conversions were at an LHSV of 0.5 hr-1 and temperature of 395°C with treated HGO having HDS of 97.5% and HDN of 90.3%; while non-treated HGO having HDS of 94.9% and HDN of 78.3%. Employing the power law model, the results indicated that for treated HGO the reaction order for both HDS and HDN was 1.50; while for non-treated HGO the reaction order for HDS was 2.25 and for HDN was 2.00. The activation energies were then calculated with 141.4 kJ/mol being obtained for HDS and 113.8 kJ/mol for HDN for treated HGO; while for non-treated HGO the activation energy for HDS was 150.4 kJ/mol and for HDN was 121.4 kJ/mol. It was observed that the conversion of both HDS and HDN were higher and the activation energies were lower for treated HGO, indicating that the removal of non-basic nitrogen species prior to hydrotreatment had a positive impact on catalyst performance and consequently the level of conversion.