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Made available in DSpace on 2015-09-25T12:19:48Z (GMT). No. of bitstreams: 1 Wagner Moreira de Almeida.pdf: 1432955 bytes, checksum: 9f9e1908144e3a096cc5d323e4c426a2 (MD5) Previous issue date: 2012-08-31 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Titanium dioxide (TiO2) shows significant catalytic, optical and electronic properties, being used as constitutional material to capacitors, pigments and solar cells, as well as, applied as catalyst for photodegradation of organic matter. Thus, this work aims to obtain TiO2 and Ag-doped TiO particles, under several calcinations temperatures and with different silver content, by means of the Polymeric Precursor Method. Also, evaluate its photocatalytic activities during the photooxidation of indigo blue dye. Therefore, all samples were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA) and differential thermal analysis (DTA). Besides, the influence thermal treatment and the dopant metal over both oxides structures were investigated by X-ray diffraction (XRD). In general, the apparent kinetic constant suggests that TiO2 /(0.50%)Ag (700 ºC) sample leads to higher conversion of the dye, even under visible light irradiation. / O dióxido de titânio (TiO2) possui importantes propriedades catalíticas, eletrônicas, sendo utilizado na produção de capacitores, pigmentos, células solares e na degradação de poluentes orgânicos. No presente trabalho, foi realizado a síntese de catalisadores de TiO2 e TiO dopado com prata metálica a diferentes concentrações e temperaturas de calcinação, a partir do método dos precursores poliméricos, que proporciona um controle preciso da estequiometria e uma maior reprodutibilidade, para avaliar a atividade fotocatalítica na degradação do corante Índigo Blue sob radiação artificial visível. As amostras de TiO22 e Ag/TiO foram analisados por espectroscopia de infravermelho, termogravimetria (TG) e análise térmica diferencial (DTA). Foi realizado também o estudo da influência da temperatura de calcinação e porcentagem do dopante prata na evolução das fases cristalinas (anatase e rutilo), por meio de difração de raios X (DRX). Na cinética de degradação do corante índigo blue verificou-se, com relação aos valores da constante cinética aparente (k2), que a amostra de Ag0,50/TiO (700 ºC), apresentou maior eficiência de degradação na atividade fotocatalítica, a luz visível, o que é consistente com os resultados de DRX.

L'hydroformylation (l’action d’un mélange gazeux CO/H2 sur une liaison C=C en présence d’un catalyseur métallique pour former des aldéhydes) du 10-undécénitrile (une oléfine biosourcée obtenue à partir d'huile de ricin) a été étudiée. Elle représente une étape clé dans la synthèse de monomères vers le polyamide-12. La combinaison in situ de Rh(acac)(CO)2 avec 20 équivalents de Biphephos, un ligand biphosphite encombré, conduit à une régiosélectivité (rapport aldéhyde linéaire/branché, l/b jusqu’à 99:1), une chimiosélectivité (jusqu’à 74% d’aldéhydes) et une activité (TOF jusque 28,000 mol(aldéhydes).mol(Rh)-1.h-1) optimisées. Les conditions opératoires, en particulier le rapport substrat-catalyseur, ont une forte influence sur l’isomérisation de la liaison C=C: une forte rétro-isomérisation des alcènes internes en oléfines terminales peut être observée sous certaines conditions. L’isomérisation-hydroformylation de l'oléonitrile (une autre oléfine grasse biosourcée avec une liaison C=C en milieu de chaine) a aussi été étudiée. Nous avons également démontré que la combinaison in situ de précurseurs de ruthénium, un métal significativement moins cher mais moins étudié, avec le ligand Biphephos conduit à des productivités élevées et à des sélectivités identiques à celles obtenues avec le système Rh-Biphephos. Le recyclage du catalyseur par nanofiltration organique (OSN) a été validé (99% de recyclage du système catalytique Rh-Biphephos). La modification du Biphephos pour améliorer sa récupération par nanofiltration a été entreprise: une nouvelle synthèse impliquant une étape de métathèse croisée avec des acrylates a été validée et des ligands avec un volume plus important, et possiblement une affinité différenciée vis-à-vis de la membrane, ont été développés. / Hydroformylation (action of syngas on C=C bonds in presence of a transition metal-catalyst to form aldehydes) of 10-undecenitrile (a bio-sourced fatty olefin obtained from castor oil) was studied as a key reaction step toward the formation of monomers for polyamide-12 synthesis. In situ combination of Rh(acac)(CO)2 with 20 equiv of Biphephos, a bulky biphosphite ligand, led to optimized regioselectivity (linear-to-branched aldehyde ratio; l/b up to 99:1), chemoselectivity (up to 74% of aldehyde) and activity (TOF up to 28,000 mol(aldehydes).mol(Rh)-1.h-1). Reaction conditions, in particular the substrate-to-catalyst ratio, have a strong influence on the extent of the isomerization side-reaction: a strong back-isomerization of internal alkenes into terminal olefins was observed under specific conditions. Tandem isomerization-hydroformylation was also investigated through the prism of oleonitrile (another biosourced long-chain fatty olefin with a C=C bond in remote internal position). It was also demonstrated that in situ combinations of ruthenium precursors, a much cheaper but poorly studied metal, with Biphephos lead to high productivities and similar selectivities than Rh-based systems. Catalyst recycling by Organic Solvent Nanofiltration (OSN) was possible (99% of Rh-Biphephos catalytic system recovery). Structural modification of Biphephos to improve its recovery by OSN was undertaken. An original synthetic pathway involving insertion of vinyl moieties on the Biphephos frame to perform cross-metathesis with acrylates was validated and ligands with a higher volume, and possibly different affinity toward organic membranes, were undertaken.

<p>A significant number of resources are allocated to maintaining the resiliency of pharmaceutical supply chain as failure to do so thoroughly can result in drug shortages of essential medicines. Recently, the effects of COVID-19 exacerbated flaws in the current system causing the pharmaceutical industry and government organizations and to reassess relief strategies that could also strengthen the supply chain. Flow chemistry has become an attractive and prominent platform enabling continuous manufacturing (CM) technologies to synthesize active pharmaceutical ingredients (API) quickly according to demand. Compared to traditional batch chemistry, flow chemistry has demonstrated to be more robust in terms of throughput, scalability, and hazard reduction while maintaining a high degree of control and product quality. This work demonstrates these capabilities in reaction optimization and discovery with the overarching goal of domesticating CM to make essential medicines more affordable. A two-step process for the synthesis in diazepam was developed using a Chemtrix Labtrix S1 and Start microfluidic systems where purities as high as 98% were achieved. The system was successfully scaled up to a larger system that was able to produce 96% pure diazepam at a 91% yield. </p>

La synthèse de nitriles gras à partir de ressources renouvelables est un domaine qui attire depuis quelques temps les industries de la parfumerie, des polymères et des biocarburants pour avion. Ce travail de thèse s’est plus particulièrement intéressé à réduire de 100°C la température de travail pour les procédés en phase liquide et gaz, au moyen de catalyseurs plus efficaces. Le procédé en phase liquide a été étudié en terme de catalyse homogène et les formes actives à base de zinc ou indium ont été plus particulièrement détaillées ; des conditions ont été établies pour obtenir une réduction de 50°C de la température de travail. Le procédé en phase gaz a été étudié en terme de catalyse hétérogène, les catalyseurs obtenus ou synthétisés étant caractérisés par microcalorimétrie d’adsorption ; des corrélations entre la conversion de l’ester et l’acidité du lit catalytique ont été trouvées à 300°C, et des conditions expérimentales ont été développées pour obtenir une conversion totale à une température réduite de 100°C sur des catalyseurs choisis / The production of fatty nitriles from renewable sources has lately become attractive for the perfume, polymer and aviation biofuel industry. The present work investigated both liquidand gas-phase processes in the aim of developing catalysts working at 200°C, this is 100°C lower than the state-of-the-art. Homogeneous catalysis was described with zinc and indium based species for the liquid-phase process, succeeding in reducing by 50°C the operating temperature. Heterogeneous catalysts with acid-base features were characterized by adsorption calorimetry and tested in the gas-phase process, leading to correlations between acidity and ester conversion at 300°C, while conditions were found on selected catalysts in order for the process to perform the complete conversion of esters into nitriles at 200°C

<p>The development of new materials has been inspired by lessons learned from natural systems. In the area of underwater adhesion and adhesives, inspiration has come from the complex protein adhesives generated by marine organism such as barnacle and mussels. These protein systems have a high incorporation of a unique amino acid, dihydroxyphenylalanine, and provides the unique adhesive qualities synthetic systems strive to emulate.</p> <p>By understanding how marine mussels stick to a variety of surfaces, new strategies can be explored for preventing the adhesion of biological organisms to various substrates. A continuous concern for marine vessels is the detrimental impact caused by biofouling on the hull of the ship. Fuel consumption can increase as the vessel’s drag increasing fuel consumption and non-native species can be introduced into new environments. Taking inspiration from catechol curing, new oxidative surfaces were investigated as potential antifouling coatings.</p> <p>Further insight into the marine mussels ability to apply and cure its adhesive on a variety of substrate has also inspired various synthetic polymers. The catechol moiety can be incorporated into a polymer backbone to give a new solvent based adhesive. Further investigation of the poly(styrene-co-(3,4-dihydroxystyrene)) adhesive system was done to formulate an underwater adhesive for unique use cases. A terpolymer was also explored as an ideal adhesive taking inspiration from the mussels by incorporating flexible, stiff, and sticky components to give a tunable adhesive.</p> <p>Having a strong bonding synthetic adhesive that can be used on a laboratory scale is good for academic investigation, but not of use outside the lab if it cannot easily be produced on a commercial scale. With the goal of large scale synthesis, a new polymerization method was introduced addressing some of the issues currently preventing commercial scale production.</p><br>