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L'histoire des isotopes stables débute en 1913 avec les travaux de Frederick Soddy. Dès lors les techniques analytiques dans ce domaine vont constamment évoluer permettant de répondre à des questions scientifiques de plus en plus élaborées et d'investir petit à petit de plus en plus de domaines où leur capacité de traceur devient aujourd'hui indispensable. Ce travail présente d'abord une partie décrivant l'évolution des techniques de mesures des rapports isotopiques au cours des décennies, insistant sur l'apport fondamental du flux continu et en particulier de l'analyse élémentaire. Dans la deuxième partie nous allons illustrer l'importance des analyses isotopiques dans le domaine des reconstructions paléoenvironnementales afin de mieux appréhender l'histoire climatique de la Terre et de ses habitants à diverses époques. Ceci principalement au moyen des analyses 180/160 sur des matrices phosphatées ou carbonatées. La troisième partie est consacrée à l'utilisation des isotopes stables comme traceurs de certaines réaction métaboliques fondamentales sur des échantillons fossiles mais également sur du matériel actuel. Dans ce dernier cas, nous nous sommes également servis de la capacité des isotopes stables à être utilisés comme traceurs en abondance naturelle mais également en utilisant le marquage isotopique. Pour ce faire nous avons utilisé les signatures isotopiques 180/160 sur du matériel phosphaté mais également les rapports isotopiques 13C/12C et 15N/14N de la matière organique. La quatrième partie est consacrée plus particulièrement à des travaux de développement analytiques dans divers domaines. Tout d'abord nous nous sommes intéressés aux analyses isotopiques D/H et 180/160 des eaux. Nous proposons de nouveaux paramètres de correction des analyses isotopiques sur des eaux de salinités supérieures à l'eau de mer. Puis nous avons travaillé sur les analyses isotopiques 13C/12C et 180/160 des carbonates en proposant de nouveaux paramètres pour le fractionnement isotopique de l'oxygène entre les carbonates d'apatites et l'eau, les fractionnements isotopiques du carbone et de l'oxygène entre aragonite et calcite sur des organismes vivants actuels. Nous avons également développé une technique semi-automatique pour déterminer les signatures isotopiques en carbone et en oxygène de la calcite et de la dolomite dans des mélanges de proportions variables. Enfin nous avons tenté de quantifier la variabilité naturelle et la variabilité instrumentale des analyses isotopiques du carbone et de l'oxygène sur des microfossiles. Puis, nous nous sommes intéressés à un domaine représentant une part importante de notre travail analytique sur les analyses isotopiques 180/160 des phosphates biogéniques. En collaboration avec les fabricants d'instruments nous avons développé un nouveau système afin d'améliorer la qualité des analyses, de les automatiser le plus possible et de réduire la taille de la prise d'essai dans le but d'accéder à des échantillons de taille plus réduite. Enfin nous avons développé les analyses isotopiques du soufre toujours en collaboration avec les fabricants d'instrumentation, d'une part pour évaluer la capacité d'un nouveau système analytique à produire des analyses fiables sur des quantités limitées au sein de matrices complexes, et d'autre part, la capacité du même système à produire des analyses multi-isotopiques fiables sur les trois éléments N, C, S. Dans la conclusion de ce travail, nous revenons sur la contribution de nos divers travaux à l'évolution des techniques isotopiques en essayant d'évaluer dans l'avenir les nouveaux champs d'investigation de ces techniques tout juste centenaires / The history of stable isotopes began in 1913 with the work of Frederick Soddy. Since then, analytical techniques in that domain have been in constant evolution, providing answers to more and more elaborated scientific questions and spreading into various application fields where their tracing abilities have become extremely useful today. This work first describes the evolution of those analytical techniques through time and especially the fundamental step forward with continuous flow techniques especially through elemental analysis. For the second part we illustrate the importance of stable isotope analyses for paleoenvironmental reconstructions to better understand the climatic history of the Earth and its inhabitants from different periods. This is mainly based on 180/160 analyses from phosphatic or carbonaceous matrices. The third part is dedicated to the use of stable isotopes as tracers of various fundamental metabolic pathways from both fossil and actual samples. For this latter case we have used the capacity of stable isotopes to be used at natural abundance as well as artificially labelled. We have used 180/160 isotopic signatures from phosphatic samples as well as 13C/12C and 15N/14N from organic matter. The fourth part is dedicated to analytical developments covering several domains. First we investigated D/H and 180/160 measurements from waters. We are proposing new correction parameters for isotopic measurements from waters with salinity higher than sea water. Then we have dealt with 13C/12C and 180/160 isotopic analyses from carbonates and we suggest new parameters to constrain oxygen isotopic fractionation between carbonates from apatite and water as well as carbon and oxygen isotopic fractionation between calcite and aragonite from actual living organisms. We have also developed a new semi-automated technique to measure carbon and oxygen isotopic signatures from calcite and dolomite mixtures with various proportions. Then we have attempted to quantify the natural and instrumental variability of oxygen and carbon isotopic analyses from microfossils. An important part of this analytical work has been dedicated to 180/160 isotopic analyses from biogenic phosphate material. ln collaboration with instrument manufacturers we have developed a new system to improve both quality and automation of those measurements as well as reduce the aliquot sizes in order to get access to smaller samples. Eventually we have developed sulfur isotopic analyses in collaboration with instrument manufacturers to evaluate the capacities of a new analytical setup to generate reliable N, C, S multi- isotopic analyses. Last, we summarize the contribution of this work to the evolution of stable isotope techniques and we try to evaluate the future fields of investigation for those techniques just over one hundred years old

Neste trabalho foi avaliada a permeação/penetração cutânea in vitro (pele suína) de propionato de clobetasol nanoencapsulado incorporado em um semissólido, empregando células de difusão de Franz. A nanoencapsulação foi capaz de reduzir a quantidade de fármaco que penetra nas camadas da pele (estrato córneo, epiderme e derme) sem alterar a forma (distribuição percentual) como o propionato de clobetasol se distribui. A adequabilidade de diferentes membranas sintéticas (acetato de celulose, policarbonato e membrana de diálise) para a avaliação da liberação in vitro, empregando células de difusão de Franz, a partir desta formulação foi também estudada. A partir da combinação de diferentes técnicas analíticas (espalhamento de luz dinâmica, microscopias eletrônicas de transmissão e varredura) foi observado que a membrana de menor tamanho de poro (membrana de diálise, 12 kDa de cut off) é a mais adequada para a condução deste tipo de avaliação, pois é a única capaz de evitar a passagem de nanocápsulas íntegras da formulação para o meio receptor das células de difusão, em detrimento das membranas de policarbonato e acetato de celulose (0,05 μm e 0,45 μm de tamanho de poro, respectivamente). Além disso, uma nova estratégia para a avaliação da liberação in vitro de fármacos associados a nanocápsulas de núcleo lipídico, combinando fluxo contínuo de meio de liberação e sacos de diálise foi proposta neste trabalho. A técnica mostrou-se adequada para a obtenção do perfil de liberação in vitro a partir de suspensões de nanocápsulas contendo diferentes fármacos modelo (prednisolona e propionato de clobetasol), possibilitando a diferenciação destes sistemas de soluções contendo os fármacos livres, graficamente e pelos valores de fluxo calculados. Adicionalmente, esta estratégia mostrou-se apropriada para a manutenção da concentração de fármaco no meio de liberação afastada da saturação, contribuindo para o atendimento da condição sink. Ainda, classificamos o sistema como um protótipo semi-automatizado para a avaliação da liberação in vitro de fármacos, capaz de gerar resultados com maior precisão em relação à diálise convencional. / The in vitro cutaneous permeation/penetration (porcine skin) of clobetasol propionate-loaded lipid-core nanocapsules incorporated into a semisolid dosage form was evaluated, using the Franz diffusion cells technique. It was shown that the nanoencapsulation was able to reduce the drug amount penetration into skin layers (stratum corneum, epidermis and dermis) without changing the way (percentual distribution) that it was distributed. The suitability of different synthetic membranes (cellulose acetate, polycarbonate, and dialysis membrane) to assess the in vitro drug release using Franz diffusion cells from this formulation was also studied. It was ascertained by combining different analytical techniques (dynamic light scattering, scanning and transmition electron microscopy) that the membrane with smaller pore size (dialysis membrane, 12 kDa cut off) is the most appropriate for conducting this kind of study, because it is the only one able of preventing the passage of intact nanocapsules from formulation to Franz diffusion cells receptor media, instead of polycarbonate and cellulose acetate membranes (0.05 and 0.45 pore size, respectively). In addition, a new strategy to assess in vitro drug release drug-loaded lipid-core nanocapsules was proposed, associating continuous flow of release media and dialysis sac. The proposed system was adequate to assess the in vitro drug release profiles from nanocapsule suspensions containing different model drugs (prednisolone and clobetasol propionate), enabling the differentiation of these systems from drug solutions, graphically and by the calculated flux values. Furthermore, this strategy was suitable to maintain the drug concentration into release media far away from saturation, contributing to the sink condition. Also, the proposed system was described as a semi-automated prototype for in vitro drug release evaluation, able to produce results with greater accuracy than conventional dialysis technique.

Neste trabalho foi avaliada a permeação/penetração cutânea in vitro (pele suína) de propionato de clobetasol nanoencapsulado incorporado em um semissólido, empregando células de difusão de Franz. A nanoencapsulação foi capaz de reduzir a quantidade de fármaco que penetra nas camadas da pele (estrato córneo, epiderme e derme) sem alterar a forma (distribuição percentual) como o propionato de clobetasol se distribui. A adequabilidade de diferentes membranas sintéticas (acetato de celulose, policarbonato e membrana de diálise) para a avaliação da liberação in vitro, empregando células de difusão de Franz, a partir desta formulação foi também estudada. A partir da combinação de diferentes técnicas analíticas (espalhamento de luz dinâmica, microscopias eletrônicas de transmissão e varredura) foi observado que a membrana de menor tamanho de poro (membrana de diálise, 12 kDa de cut off) é a mais adequada para a condução deste tipo de avaliação, pois é a única capaz de evitar a passagem de nanocápsulas íntegras da formulação para o meio receptor das células de difusão, em detrimento das membranas de policarbonato e acetato de celulose (0,05 μm e 0,45 μm de tamanho de poro, respectivamente). Além disso, uma nova estratégia para a avaliação da liberação in vitro de fármacos associados a nanocápsulas de núcleo lipídico, combinando fluxo contínuo de meio de liberação e sacos de diálise foi proposta neste trabalho. A técnica mostrou-se adequada para a obtenção do perfil de liberação in vitro a partir de suspensões de nanocápsulas contendo diferentes fármacos modelo (prednisolona e propionato de clobetasol), possibilitando a diferenciação destes sistemas de soluções contendo os fármacos livres, graficamente e pelos valores de fluxo calculados. Adicionalmente, esta estratégia mostrou-se apropriada para a manutenção da concentração de fármaco no meio de liberação afastada da saturação, contribuindo para o atendimento da condição sink. Ainda, classificamos o sistema como um protótipo semi-automatizado para a avaliação da liberação in vitro de fármacos, capaz de gerar resultados com maior precisão em relação à diálise convencional. / The in vitro cutaneous permeation/penetration (porcine skin) of clobetasol propionate-loaded lipid-core nanocapsules incorporated into a semisolid dosage form was evaluated, using the Franz diffusion cells technique. It was shown that the nanoencapsulation was able to reduce the drug amount penetration into skin layers (stratum corneum, epidermis and dermis) without changing the way (percentual distribution) that it was distributed. The suitability of different synthetic membranes (cellulose acetate, polycarbonate, and dialysis membrane) to assess the in vitro drug release using Franz diffusion cells from this formulation was also studied. It was ascertained by combining different analytical techniques (dynamic light scattering, scanning and transmition electron microscopy) that the membrane with smaller pore size (dialysis membrane, 12 kDa cut off) is the most appropriate for conducting this kind of study, because it is the only one able of preventing the passage of intact nanocapsules from formulation to Franz diffusion cells receptor media, instead of polycarbonate and cellulose acetate membranes (0.05 and 0.45 pore size, respectively). In addition, a new strategy to assess in vitro drug release drug-loaded lipid-core nanocapsules was proposed, associating continuous flow of release media and dialysis sac. The proposed system was adequate to assess the in vitro drug release profiles from nanocapsule suspensions containing different model drugs (prednisolone and clobetasol propionate), enabling the differentiation of these systems from drug solutions, graphically and by the calculated flux values. Furthermore, this strategy was suitable to maintain the drug concentration into release media far away from saturation, contributing to the sink condition. Also, the proposed system was described as a semi-automated prototype for in vitro drug release evaluation, able to produce results with greater accuracy than conventional dialysis technique.

abstract: Continuous monitoring in the adequate temporal and spatial scale is necessary for a better understanding of environmental variations. But field deployments of molecular biological analysis platforms in that scale are currently hindered because of issues with power, throughput and automation. Currently, such analysis is performed by the collection of large sample volumes from over a wide area and transporting them to laboratory testing facilities, which fail to provide any real-time information. This dissertation evaluates the systems currently utilized for in-situ field analyses and the issues hampering the successful deployment of such bioanalytial instruments for environmental applications. The design and development of high throughput, low power, and autonomous Polymerase Chain Reaction (PCR) instruments, amenable for portable field operations capable of providing quantitative results is presented here as part of this dissertation. A number of novel innovations have been reported here as part of this work in microfluidic design, PCR thermocycler design, optical design and systems integration. Emulsion microfluidics in conjunction with fluorinated oils and Teflon tubing have been used for the fluidic module that reduces cross-contamination eliminating the need for disposable components or constant cleaning. A cylindrical heater has been designed with the tubing wrapped around fixed temperature zones enabling continuous operation. Fluorescence excitation and detection have been achieved by using a light emitting diode (LED) as the excitation source and a photomultiplier tube (PMT) as the detector. Real-time quantitative PCR results were obtained by using multi-channel fluorescence excitation and detection using LED, optical fibers and a 64-channel multi-anode PMT for measuring continuous real-time fluorescence. The instrument was evaluated by comparing the results obtained with those obtained from a commercial instrument and found to be comparable. To further improve the design and enhance its field portability, this dissertation also presents a framework for the instrumentation necessary for a portable digital PCR platform to achieve higher throughputs with lower power. Both systems were designed such that it can easily couple with any upstream platform capable of providing nucleic acid for analysis using standard fluidic connections. Consequently, these instruments can be used not only in environmental applications, but portable diagnostics applications as well. / Dissertation/Thesis / Ph.D. Electrical Engineering 2013

Neste trabalho foi avaliada a permeação/penetração cutânea in vitro (pele suína) de propionato de clobetasol nanoencapsulado incorporado em um semissólido, empregando células de difusão de Franz. A nanoencapsulação foi capaz de reduzir a quantidade de fármaco que penetra nas camadas da pele (estrato córneo, epiderme e derme) sem alterar a forma (distribuição percentual) como o propionato de clobetasol se distribui. A adequabilidade de diferentes membranas sintéticas (acetato de celulose, policarbonato e membrana de diálise) para a avaliação da liberação in vitro, empregando células de difusão de Franz, a partir desta formulação foi também estudada. A partir da combinação de diferentes técnicas analíticas (espalhamento de luz dinâmica, microscopias eletrônicas de transmissão e varredura) foi observado que a membrana de menor tamanho de poro (membrana de diálise, 12 kDa de cut off) é a mais adequada para a condução deste tipo de avaliação, pois é a única capaz de evitar a passagem de nanocápsulas íntegras da formulação para o meio receptor das células de difusão, em detrimento das membranas de policarbonato e acetato de celulose (0,05 μm e 0,45 μm de tamanho de poro, respectivamente). Além disso, uma nova estratégia para a avaliação da liberação in vitro de fármacos associados a nanocápsulas de núcleo lipídico, combinando fluxo contínuo de meio de liberação e sacos de diálise foi proposta neste trabalho. A técnica mostrou-se adequada para a obtenção do perfil de liberação in vitro a partir de suspensões de nanocápsulas contendo diferentes fármacos modelo (prednisolona e propionato de clobetasol), possibilitando a diferenciação destes sistemas de soluções contendo os fármacos livres, graficamente e pelos valores de fluxo calculados. Adicionalmente, esta estratégia mostrou-se apropriada para a manutenção da concentração de fármaco no meio de liberação afastada da saturação, contribuindo para o atendimento da condição sink. Ainda, classificamos o sistema como um protótipo semi-automatizado para a avaliação da liberação in vitro de fármacos, capaz de gerar resultados com maior precisão em relação à diálise convencional. / The in vitro cutaneous permeation/penetration (porcine skin) of clobetasol propionate-loaded lipid-core nanocapsules incorporated into a semisolid dosage form was evaluated, using the Franz diffusion cells technique. It was shown that the nanoencapsulation was able to reduce the drug amount penetration into skin layers (stratum corneum, epidermis and dermis) without changing the way (percentual distribution) that it was distributed. The suitability of different synthetic membranes (cellulose acetate, polycarbonate, and dialysis membrane) to assess the in vitro drug release using Franz diffusion cells from this formulation was also studied. It was ascertained by combining different analytical techniques (dynamic light scattering, scanning and transmition electron microscopy) that the membrane with smaller pore size (dialysis membrane, 12 kDa cut off) is the most appropriate for conducting this kind of study, because it is the only one able of preventing the passage of intact nanocapsules from formulation to Franz diffusion cells receptor media, instead of polycarbonate and cellulose acetate membranes (0.05 and 0.45 pore size, respectively). In addition, a new strategy to assess in vitro drug release drug-loaded lipid-core nanocapsules was proposed, associating continuous flow of release media and dialysis sac. The proposed system was adequate to assess the in vitro drug release profiles from nanocapsule suspensions containing different model drugs (prednisolone and clobetasol propionate), enabling the differentiation of these systems from drug solutions, graphically and by the calculated flux values. Furthermore, this strategy was suitable to maintain the drug concentration into release media far away from saturation, contributing to the sink condition. Also, the proposed system was described as a semi-automated prototype for in vitro drug release evaluation, able to produce results with greater accuracy than conventional dialysis technique.

The presDue to the system does not recognize equations and formulas the resumo and abstract can be found in the PDF file. / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Devido ao sistema não reconhecer equações e fórmulas o resumo e abstract encontra-se no arquivo em PDF.

Cette thèse décrit l’exploration de techniques de catalyse et de flux continu pour faciliter la fermeture de molécules cycliques tendues. En premier lieu, un catalyseur de palladium permet de fermer un hétérocycle aromatique tendu, la structure benzo[a]imidazo[2,1,5-c,d]indolizine.16 La tension de cycle contribue à donner au système  hautement délocalisé de ces molécules des propriétés photophysiques intéressantes, différentes de celles de leurs analogues non tendus.21,33 Il a été démontré que leur longueur d’onde d’émission maximale peut être modulée de manière prévisible en modifiant les groupes fonctionnels conjugués au système aromatique. Le potentiel d’application en biochimie de ces fluorophores à déplacement de Stokes élevé a été exploré en étiquetant deux protéines en milieu biocompatible. En second lieu, une version catalytique de la cycloaddition de Simmons-Smith a été optimisée. Dans cette transformation, une quantité catalytique d’un sel de zinc permet de former un carbénoïde hautement réactif à partir d’un composé aryldiazométhane. Ce carbénoïde peut réagir avec une grande variété d’alcènes pour former les arylcyclopropanes correspondants. Un catalyseur modifié permet même à la réaction d’avoir lieu en présence d’alcools primaires. Enfin, la manipulation des composés aryldiazométhanes utilisés dans la cyclopropanation décrite ci-haut peut s’avérer risquée vu la toxicité et l’instabilité de ces composés. Pour minimiser ces risques, une méthode pour générer et purifier ces réactifs en flux continu a été développée. De cette manière, le composé dangereux est consommé à mesure qu’il est généré, dans un système fermé. Un large éventail d’aryldiazométhanes peut être produit en solution dans un solvant non-coordinant. La compatibilité de ces solutions avec des systèmes catalytiques requérant des réactifs propres et secs a été démontrée. / This thesis describes the exploration of catalysis and continuous flow techniques towards the formation of strained cyclic molecules. First, a palladium catalyst enables the ring closure of a strained aromatic heterocycle, the benzo[a]imidazo[2,1,5-c,d]indolizine.16 Ring strain gives these molecule’s highly delocalized  system interesting photophysical properties that differ from those of unstrained analogs.21,33 Their emissive properties can be predictably modulated by modifying functional groups conjugated to the aromatic core. These high Stokes-shift fluorophores’ application potential in biochemistry was explored by the biocatalyzed labelling of two proteins in biocompatible media. Second, a catalytic version of the Simmons-Smith cycloaddition was optimized. In this transformation, a catalytic amount of zinc salt allows the formation of a highly reactive carbenoid from an aryldiazomethane precursor. This intermediate can then react with a variety of alkenes, forming the corresponding arylcyclopropanes. A modified catalyst even enables the reaction to proceed in the presence of a primary alcohol group. Finally, the handling of the aryldiazomethane precursors used in the above reaction can be hazardous due to these compound’s instability and toxicity. To minimise these risks, a method to synthesise and purify these reagents in continuous flow was developed. This way, the dangerous chemical is consumed as it is generated, in a closed system. A large array of aryldiazomethane solutions in a non-coordinating solvent can be produced. These solutions’ compatibility with sensitive catalytic systems requiring clean and dry reagents was demonstrated.

L'objectif de ce projet de thèse a été d’étudier l’activité catalytique de catalyseurs commerciaux contenant de nanoparticules métalliques pour l'hydrogénation du limonène. La réaction a été réalisée en l'absence de solvants et dans des conditions douces c’est à dire à basse température (30°C) et sous faible pression d'hydrogène (3 bar), conduisant à une production stable du (+)-p-1-menthene. Dans notre étude, les nanoparticules métalliques actives (Pt, Pd et Ru) et les supports (carbone, silice et alumine) ont été systématiquement modifiés et testés dans des conditions de réaction modérées (température ambiante, 3 bar H2). Notre étude a révélé une activité et sélectivité importante du catalyseur hétérogène Pt/C pour la réduction du R-(+)-limonène en (+)-p-1-menthène qui est le produit partiellement hydrogéné. Le Pt/C ainsi que Pt/Al2O3 est l’un des systèmes les plus actifs parmi les catalyseurs actuellement disponibles dans le commerce. De plus, l'activité catalytique et la stabilité de Pt/C ont été maintenues au cours des essais de recyclage en réacteur fermé. Ce catalyseur a également été utilisé en réacteur à flux continu, donnant des résultats prometteurs. L'hydrogénation sélective de la liaison C=C terminale du limonène par rapport de la liaison interne a été rationalisée par des études cinétiques détaillées qui révèlent une vitesse 8 fois plus importante par la double liaison terminale. Cette première étude nous a permis de développer la synthèse de nouveaux catalyseurs hétérogènes contenant diverses nanoparticules métalliques (Pt, Ru, Pt3Sn et Ni). Ils ont été préparés à partir d'une approche colloïdale et ont été testés dans l'hydrogénation de limonène. Ces catalyseurs contiennent la même charge métallique et des tailles de particules similaires (environ 2 nm) dispersées de façon homogène sur des oxydes non structurés (silice et d'alumine), du carbone, ou incorporés à l'intérieur des murs ou à la surface des pores de matériaux mésostructurés siliciques (SBA-15). L’ensemble des catalyseurs de la série du Pt ont révélés une activité accrue lors de l'hydrogénation sélective du limonène en p-menthène puis en p-menthane avec une vitesse de réaction très élevé. Parmi tous ces catalyseurs, celui contenant des nanoparticules de Pt dans les murs de la silice a montré au bout de deux heures de réaction un TOF d'environ 2200 h-1 et un rendement maximal pour le p-menthène d'environ 85% après 10 heures de réaction. Ce même catalyseur a été testé dans un réacteur en flux continu et affiche après 6 heures un rendement en p-menthene stable de 80%. Aucun produit d'isomérisation n’a été détecté dans le mélange brut au cours de la réaction. En conclusion, nous pouvons dire que l'utilisation d'un catalyseur hétérogène commercial comme le Pt/C ou l’utilisation d’un catalyseur hétérogène métallique développé à partir d'une approche colloïdale, Pt@SBA-15{murs}, permet d'obtenir une conversion sélective du limonène en p-menthène en réacteur fermé ainsi également en réacteur à flux continu. Des informations sur la cinétique de cette réaction ont également pu être obtenues / The goal of this PhD project was in an early stage to study the activities of several commercial metal nanoparticles based catalysts for the mild hydrogenation of limonene. The hydrogenation of limonene has been performed in neat limonene and under mild conditions, e.g. low temperature (30°C) and low molecular hydrogen pressure (3 bar), aiming at a sustainable production route for (+)-p-1-menthene. In our study, the active metal nanoparticles (Pt, Pd and Ru) and supports (carbon, silica and alumina) were systematically varied and tested. It was found that the heterogeneous catalyst Pt/C alongside Pt/Al2O3 under mild reaction conditions (room temperature and 3 bar H2) was highly active and selective in the reduction of R-(+)-limonene to the partial hydrogenation product (+)-p-1-menthene. Moreover, the catalytic activity and stability of Pt/C were maintained during recycling tests under batch conditions and thus allowed the implementation of this catalytic system into continuous flow operation. The selective hydrogenation of terminal C=C bond over the internal one in limonene was rationalized by detailed kinetic studies which revealed an 8-fold difference in reaction rate between the two reactions. This previous study with commercial catalysts gave the possibility to tune the synthesis of heterogeneous metal-based catalysts for the next step of the study, where different heterogeneous metal based catalysts (Pt, Ru, Pt3Sn, and Ni), developed from a colloidal-based approach were tested in the hydrogenation of limonene. Those catalysts contain the same metal loading and similar particle sizes (ca. 2 nm) homogeneously dispersed onto non structured oxides (silica and alumina), carbon, or embedded into the walls or at the pore surface of a mesostructured silica materials (SBA-15). All the catalysts from the Pt series were particularly active in the selective hydrogenation of limonene towards p-menthene with further conversion into p-menthane, showing a very high reaction rate. Among of all those catalysts, the one containing Pt nanoparticles embedded in the walls of the silica showed the highest TOF, of ca. 2200 h-1 after two hours of reaction and a maximum yield in p-menthene of ca. 85 % was obtained after 10 hours of reaction. The same catalyst was tested in a continuous flow system and a stable yield of ca. 80% during 6 hours of reaction was reached. No products of isomerization were detected in the crude mixture during the reaction. We could therefore conclude that, using either a heterogeneous commercial catalyst like Pt/C or using a heterogeneous metal based catalyst developed from a colloidal-based approach like SBA-15{walls}, it was possible to achieve a selective conversion of limonene into p-menthene in batch and in continuous flow conditions

Les oligosaccharides et les glycoconjugués jouent des rôles essentiels dans de nombreux processus biologiques. Cependant, leur synthèse est plus complexe que la majorité des autres biomolécules. Le principal défi réside souvent dans la formation de la liaison glycosidique. Il est donc toujours nécessaire de développer des réactions de glycosylation efficaces et totalement stéréosélectives, utilisant de nouveaux donneurs et permettant d'accéder à des structures glycosidiques à différentes échelles. Ces réactions sont d'autant plus intéressantes si elles utilisent des promoteurs peu chers, peu toxiques et peu dangereux pour l'environnement, comme des sels de fer. Dans ce cadre, la formation directe de b-glycosides de la N-acétyl-D-glucosamine par catalyse au triflate de fer(III) a été étudiée. Cette glycosylation peut être réalisée sous irradiation micro-ondes ou en flux continu. Les conditions d'activation sous micro-ondes ont ensuite été étendues à la synthèse de motifs de N-glycanes complexes. Cette synthèse consiste en une étape de polyglycosylation au triflate de fer(III), combinée à une étape d'introduction d'un lien moléculaire, via une nouvelle glycosylation ou une réaction de la chimie click. Enfin, une a-mannosylation utilisant le triflate de fer(III) a été découverte et mise au point. Cette glycosylation, réalisée sous activation micro-ondes, est totalement stéréosélective, même en l'absence de groupement participant. / Oligosaccharides and glycoconjugates are involved in numerous biological events. However, their synthesis is generally more complex than for other biomolecules. The main challenge is often the generation of the glycosidic bond. For this reason, it is still important to develop efficient and stereoselective glycosylations, which afford glycosides in significant amounts using new donors. These reactions are even more attractive if the promoter used is cheap, non-toxic and environmentally friendly, like iron salts. In this context, the direct synthesis of b-glycosides of N-acetyl-D-glucosamine using catalytic iron triflate(III) has been developed. This glycosylation can be performed under microwave irradiation or in continuous flow. The microwave-assisted conditions were then extended to the synthesis of complex N-glycan mimics. This synthesis is based on a polyglycosylation reaction using an iron(III) triflate catalysis coupled to another glycosylation or a click reaction to introduce a functionalized linker. Finally, an a-mannosylation promoted by iron(III) triflate has been developed. This glycosylation, performed under microwave irradiation, is completely stereoselective, even without neighbouring group participation.