The catalytic activity of metal complex exhibiting Lewis acid character (dibutyltin diacetate, dibutyltin dilaurate, butylstannoic acid and di-n-butyl-oxostannane) was investigated. These catalytic complexes have been tested in the alcoholysis of soybean and castor oils, aiming to obtain a mixture of fatty acid alkyl esters, called biodiesel. In the transesterification experiments of vegetable oils, the reactions were performed using three types of reactors. The first one consisted in a glass reactor connected to a reflux condenser (RVCR). The second device consisted of a stainless steel reactor (RP), hermetically sealed, fitted with a pressure gauge and a temperature controller. The third one was adapted to be used on a microwave system. On the last two reactor systems, the alcoholysis of triglycerides was also developed at vigorous conditions, at temperatures ranging from 80 °C and 150 °C. Comparing all reactions, the results show that the most reactive catalysts using the RVCR on the methanolysis of soybean oil are DBTDA and DBTDL with comparable performances. However, in the same reaction conditions, very low yields were observed using castor oil, and no generalizations could be pointed out. When RP were employed, better yields were obtained. When the temperature raise from 80 to 150 ºC, all catalytic systems display similar performances, indicating that temperature and solubility have significant influences on these type of catalytic systems. Very low reaction yield were observed when the microwave reactor was employed. This observation must be due to the very low rate of stirring performed on this type of reactor. In a second part of this work, it was evaluated the performance of catalysts based on tin oxide (SnO2), sulfated or not, in transesterification or esterification reactions of soybean oil and its fatty acids derivatives, respectively, in the presence of methanol. The low activity verified on these systems must be related to their structural characteristics. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Neste trabalho foi investigada a atividade catalítica de quatro complexos metálicos exibindo caráter ácido de Lewis: dibutildiacetato de estanho, dibutildilaurato de estanho, óxido de dibutil estanho e ácido butilestanóico. Esses complexos catalíticos foram testados na alcoólise do óleo de soja e de mamona, visando a obtenção de uma mistura de ésteres alquílicos de ácidos graxos, denominada biodiesel. Nos experimentos de transesterificação dos óleos vegetais, as reações foram realizadas em três tipos de reatores. O primeiro equipamento foi composto de um reator de vidro acoplado a um condensador de refluxo (RVCR). O segundo equipamento foi composto de um reator de aço inox (RP), hermeticamente fechado, equipado com um manômetro e um controlador de temperatura. O terceiro reator empregado era adaptado para ser utilizado em um sistema de microondas. Nos dois últimos sistemas de reatores, a alcoólise dos triglicerídeos foi desenvolvida em condições mais enérgicas de reação, em temperaturas que variaram entre 80 °C e 150 °C. Comparando-se todas as reações, os resultados obtidos indicam que o emprego do RVCR na metanólise do óleo de soja, os catalisadores mais ativos são o DBTDA e o DBTDL com desempenhos comparáveis. Por outro lado, empregando-se o óleo de mamona, nessa condição reacional, os rendimentos foram muito baixos, não permitindo obter generalizações. Quando do uso do RP, rendimentos superiores aos observados com o RVCR são obtidos e à medida que a temperatura aumenta de 80 a 150 ºC as reatividades dos sistemas catalíticos tornam se bastante semelhantes, indicando que fatores como temperatura e solubilidade têm influência significativa nesse tipo de sistemas catalíticos. Com o emprego do reator microondas, os rendimentos reacionais foram inferiores, provavelmente devido à baixa velocidade de agitação que tal reator pode realizar. Numa segunda parte do trabalho, foi realizado um estudo do desempenho de catalisadores a base de óxido de estanho (SnO2), sulfatado ou não, em reações de transesterificação ou esterificação de óleo de soja e seus ácidos graxos, respectivamente, na presença de metanol. A baixa atividade dos catalisadores foi relacionada às características texturais dos mesmos.

Former works of our group have demonstrated the potential of catalytic systems based on titanium and zirconium in esterification of fatty acidy derived from soybean oil, in the presence of methanol. From these results, it arise the interest of evaluate the behavior of these systems in the presence of ethanol in the transesterification of soybean oil and in the esterification of fatty acid derived from this oil. In this context, this study aimed to investigate the catalytic activity of catalysts, exhibiting general formula M(n-butoxide)x (maltolate)4-x where M is titanium or zirconium, on the ethylic esterification and transesterification of soybean oil and soybean fatty acids, for obtaining biodiesel. Six catalysts were synthesized, two based on titanium and ford based on zirconium, in which the amount of the ligand maltolate (3-hydroxi-2-methyl-4-pironate), and n-butoxide. The formation of the complexes was confirmed by infrared spectroscopy. The catalytic activity of these catalysts was evaluated in the ethylic esterification via acid-base titulation, and ethylic transesterification via gas chromatography. The complexes M(n-butoxide)x (maltolate)4-x proved to be active in esterification, with conversions up to 81%, and in the transesterification yields up to 19%. When ethanol is used, the reactivity is lower than that observed when methanol is employed. In addition, complexes of Zr showed catalytic activity higher than the complex Ti. / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Trabalhos anteriores do nosso grupo de pesquisa mostraram o potencial de sistemas catalíticos à base de titânio e zircônio em reações de esterificação de ácidos graxos do óleo de soja, na presença de metanol. A partir desses resultados, surgiu o interesse de avaliar o comportamento desses sistemas utilizando o etanol na transesterificação do óleo de soja e esterificação de ácidos graxos derivados desse óleo. Então o presente trabalho visou à utilização de catalisadores de fórmula geral M (n-butóxido)x(maltol)4-x, onde M é o titânio ou zircônio, na reação de esterificação e transesterificação etílica do óleo de soja e ácidos graxos de soja, para obtenção do biodiesel. Foram investigados seis catalisadores, dois de titânio e quatro de zircônio, nos quais foi variada a quantidade de ligante maltolato (3-hidroxi-2-metil-4-pironato) e n-butóxido. A formação dos complexos foi confirmada por espectroscopia na região do infravermelho médio. A atividade catalítica desses catalisadores foi avaliada na reação de esterificação etílica através da titulação ácido-base e na reação de transesterificação etílica através da cromatografia gasosa. Os complexos do tipo M(n-butóxido)x(maltol)4-x se mostraram ativos em reações de esterificação com conversões de até 81% e na reação transesterificação com rendimento de 19%. Quando se emprega o etanol, a reatividade é inferior àquela observada quando se emprega o metanol. Além disso, os complexos de zircônio apresentaram atividade catalítica superior aos complexos de titânio.

Made available in DSpace on 2017-07-10T18:07:57Z (GMT). No. of bitstreams: 1 Layani Crystini Antonio da Silva.pdf: 3602080 bytes, checksum: 549974109a316672aa67e6aa29fdb910 (MD5) Previous issue date: 2013-02-15 / The demand for renewable energy sources that are environmentally friendly is increasing every year, especially for biodiesel, a biofuel for use in internal combustion engines biodegradable and nontoxic. In turn, biodiesel is commercially produced by transesterification process using homogeneous catalysts such as NaOH or KOH, which possess good yields despite purification steps of biodiesel quite costly, and the raw material used has a high cost. The replacement of homogeneous catalysts by heterogeneous transesterification reactions is very promising because this method has some advantages such as easy separation of the biodiesel formed in the reaction and the catalyst and the possibility of reuse of the catalyst. This study aimed to produce biodiesel using modified clays as heterogeneous catalyst. Clays are abundant natural raw materials and therefore have a low cost, and enable manipulation of their properties. Thus, natural clays have been chemically modified by treatment with KF. After treatment the catalysts were characterized structurally by the techniques of XRF, XRD, IR, SEM and BET then applied to transesterification reactions. Tests using Hammett indicators were applied on fresh catalysts and clay, where the results confirmed a greater number of basic sites for the catalysts compared to untreated clay with KF. To achieve the goal of producing biodiesel was performed 23 factorial design for three catalysts. Thus the best yield obtained was 89% using the catalyst KF-Clay 1 in molar ratio 1:9 reaction conditions, amount of catalyst of 25% over the mass of the oil temperature of 80 ° C and 1 hour of reaction. Test was conducted with catalyst reuse Clay KF-1 that showed a gradual loss of catalytic activity and leaching tests showed that among the three catalysts used at work, Clay KF-1 shows greater stability. / A procura por fontes renováveis de energia que sejam ambientalmente corretas vem aumentando a cada ano, em especial para o biodiesel, um biocombustível para uso em motores a combustão interna biodegradável e não tóxico. Por sua vez, o biodiesel é produzido comercialmente pelo processo de transesterificação utilizando catalisadores homogêneos tais como NaOH ou KOH, que apesar de bons rendimentos possuem etapas de purificação do biodiesel bastante onerosas e, a matéria prima utilizada possui um alto custo. A substituição de catalisadores homogêneos por heterogêneos em reações de transesterificação é bastante promissora, pois este método possui algumas vantagens como fácil separação entre o biodiesel formado na reação e o catalisador e possibilidade de reuso do catalisador. Este trabalho teve como objetivo produzir biodiesel empregando argilas modificadas como catalisador heterogêneo. As argilas são matérias-primas naturais abundantes e, portanto, possuem baixo custo, além de possibilitar manipulação de suas propriedades. Desta forma, argilas naturais foram modificadas quimicamente por tratamento com KF. Após o tratamento os catalisadores obtidos foram caracterizados estruturalmente pelas técnicas de FRX, DRX, IV, MEV e BET, depois aplicados em reações de transesterificação. Testes utilizando indicadores de Hammett foram aplicados sobre as argilas in natura e catalisadores, onde os resultados comprovaram um maior número de sítios básicos para os catalisadores, quando comparados com argila sem tratamento com KF. Para alcançar o objetivo de produção de biodiesel foi realizado planejamento fatorial 23 para três catalisadores. Assim o melhor rendimento obtido foi de 89% utilizando o catalisador KF-Argila 1, nas condições reacionais razão molar 1:9, quantidade de catalisador de 25% em relação a massa do óleo, temperatura de 80 oC e 1 hora de reação. Foi realizado teste de reuso com o catalisador KF-Argila 1 que apresentou uma gradativa perda na atividade catalítica e, testes de lixiviação comprovaram que dentre os três catalisadores utilizados no trabalho, o KF-Argila 1 apresenta maior estabilidade.

Cette étude a porté sur le développement de procédés continus performants de production d’esters à partir de l’huile de tournesol hautement oléique vierge ou raffinée en réacteurs enzymatiques à lit fixe, très productifs et stables dans le temps. Un procédé de transestérification continue en réacteur à lit fixe utilisant Novozyme 435 (lipase B de candida antarctica immobilisée sur Lewatit VP OC 1600), biocatalyseur non régio-spécifique, a été optimisé pour transformer de l’huile vierge de tournesol hautement oléique en esters butyliques. Les phénomènes de partition des composés polaires (phospholipides présents initialement dans l’huile, du glycérol co-produits etc.) entre milieu réactionnel et support enzymatique ont été gérés grâce à l’utilisation de tert-butanol, un solvant polaire. Les conditions assurant le meilleur compromis entre stabilité, productivité et rendements de production d’esters ont été obtenues pour une concentration initiale en huile de 500mM et un rapport molaire entre substrats de 5. De telles conditions permettent une productivité de 13,8 tonnes.an-1.kg de Novozyme 435-1. Le réacteur ainsi dimensionné s’est avéré stable pendant 50 jours consécutifs sans aucune perte d’activité, permettant de minimiser le coût élevé de l’enzyme. L’originalité du procédé est l’utilisation d’huiles vierges contenant des antioxydants naturels (phospholipides, tocophérols etc.). Nous avons démontré que ces composés mineurs sont préservés au cours du procédé de transestérification. Cela confère aux esters formés de remarquables propriétés de résistances à l’oxydation.La pertinence économique du procédé a été améliorée grâce au développement d’un nouveau biocatalyseur sur support hydrophobe (l’Accurel MP) permettant d’éviter toute adsorption de composés polaires. Une analyse économique du procédé (maximisation de la valeur nette actualisée) a permis de rationaliser les conditions optimales d’immobilisation. Une économie de l’ordre de 50% sur les coûts générés tout au long du temps de vie du procédé a pu ainsi être obtenue. En conditions de transestérification continue, aucune différence dans le profil de produits par rapport à Novozyme 435 n’a été observée. Finalement, une alternative à la transestérification directe de l‘huile a été envisagée. Une première phase d’hydrolyse de l’huile est suivie d’un procédé de récupération des acides gras qui sont dans un second temps estérifiés enzymatiquement. Pour réaliser cette dernière étape, le meilleur système réactionnel s’est avéré être le milieu sans solvant. Un réacteur continu d’estérification de l’acide oléique avec l’isobutanol a été optimisé. Cela a permis un réacteur stable pendant 54 jours consécutifs et respectant les critères des biotechnologies blanches. Une productivité annuelle de 126 tonnes.kg de Novozyme 435-1 a été atteinte. Cela représente une amélioration de la productivité d’un facteur 9,2 par rapport au procédé de transestérification développée précédemment / This work focused on the development of efficient continuous processes for the production of esters from crude or refined high oleic sunflower oil with enzymatic packed bed reactor presenting high levels of productivity and stability. A process of continuous transesterification in packed bed reactor using Novozyme 435 (lipase B from Candida antarctica immobilized onto Lewatit VP OC 1600), a non-specific biocatalyst, was optimized to transformation of high-oleic sunflower oil into butylic esters. The phenomena of partition of polar compounds (phospholipids found in crude oils, produced glycerol etc.) between the reaction medium and the enzymatic support were managed using tert-butanol, a polar solvent. The conditions that enabled the best compromise between stability, productivity and production yields were obtained with an initial oil concentration of 500 mM and a molar ratio between co-substrates of 5. Such conditions enabled a productivity of 13.8 tons.kg-1.kg of Novozyme 435-1 to be reached. The reactor exhibited great stability for 50 consecutive days without any loss of activity. That enabled to minimize the high costs of the enzyme. The novelty of the process was the use of crude oils, containing high levels of natural antioxidants (phospholipids, tocopherols etc.). We demonstrated that these minor components of oils were preserved during the transesterification process. It conferred the synthesized esters some remarkable properties of oxidative resistance.The economic relevance of the process was improved thanks to the development of a new biocatalyst onto a very hydrophobic support (Accurel MP) in order to avoid any adsorptions of polar compounds. An economic analysis (maximisation of the net present value) enabled to rationalize the optimal immobilisation conditions. Over the whole process, it enabled a 50% saving on the global expenses.__ In continuous transesterification conditions, no difference in the product profile was noticed between the new biocatalyst and Novozyme 435.Finally, an alternative to direct transesterification of oil was considered. A first stage of oil hydrolysis is followed by a process of fatty acid recovery and a stage of enzymatic esterification into esters. In order to realize/complete this last stage, the best reaction system was a solvent-free medium. A continuous reactor for the esterification of oleic acid with isobutanol was optimized. It enabled a reactor stable/a stable reactor for 54 consecutive days, respecting the conditions of white biotechnologies. An annual productivity of 126 tons.year-1.kg of Novozyme 435-1 was reached. That represented a productivity improvement by a factor of 9.2 in comparison with the transesterification process.

La méthode de l’Analyse du Cycle de Vie (ACV) est devenue ces dernières années un outil d’aide à la décision « environnementale » pour évaluer l’impact des produits et des processus associés. La pratique de l’ACV est documentée comme un outil pour l’évaluation d’impacts, la comparaison et la prise de décisions « orientée produit ». L’exploitation d’une telle méthode pour les procédés de l’industrie bio-physico-chimique a gagné récemment en popularité. Il existe de nombreux faisceaux d’amélioration et d’expansion pour sa mise en oeuvre pour l’évaluation des procédés industriels. L’étude s’attache à la production de biocarburant à partir de la plante Jatropha curcas L. selon une approche « attributionelle ». Cette étude présente l’évaluation environnementale d’un agro-procédé et discute de l’opportunité de coupler les concepts, les méthodes et les outils de l’ACV et de l’IPAO (Ingénierie des Procédés Assistés par Ordinateur). Une première partie présente l’ACV appliquée à l’agrochimie. L’état de la littérature apporte des enseignements sur les diverses études qui mettent en évidence le rôle et l’importance de l’ACV pour les produits et les différents agro-procédés. La substitution des carburants classiques par les biocarburants est considérée comme une voie potentielle de substitution aux énergies fossiles. Leur processus se doit d’être évalué au regard de l’impact environnemental et du paradigme du développement durable, en complément des critères classiques, économiques et politiques. La deuxième partie aborde notre étude ACV de la production du biocarburant à partir de la plante Jatropha. Cette évaluation englobe la culture et la récolte en Afrique, l’extraction de l’huile et la phase de production de biocarburants, jusqu’à son utilisation par un moteur à explosion. À cet effet, les normes ISO 14040 et 14044 sont respectées. Basée sur une perspective « midpoint » avec les méthodes de calcul d’impacts, Impact 2002+ et CML, nous fournissons les premiers résultats de la phase d’interprétation (GES, appauvrissement des ressources, la couche d’ozone, l’eutrophisation et l’acidification). Cette étude démontre le potentiel de production de biocarburants de deuxième génération à réduire l’impact environnemental. Dans le même temps, elle révèle que l’unité de transesterification est le plus impactant. Nous identifions les limites de notre application selon une approche ACV « pure ». Dans la troisième partie, nous discutons des bénéfices attendus du couplage de l’ACV et des méthodes de modélisation et de simulation de l’ingénierie des procédés. Nous suggérons alors une amélioration de l’approche environnementale des systèmes de production. Nous fournissons un cadre de travail intégrant les différents points de vue, système, processus et procédé afin d’évaluer les performances environnementales du produit. Un outil logiciel, SimLCA, est développé sur la base de l’environnement Excel et est validé par l’utilisation de la solution ACV SimaPro et du simulateur de procédés Prosim Plus. SimLCA permet un couplage ACV-simulation pour l’évaluation environnementale du système complet de production de biocarburant. Cette intégration multi-niveaux permet une interaction dynamique des données, paramètres et résultats de simulation. Différentes configurations et scénarios sont discutés afin d’étudier l’influence de l’unité fonctionnelle et d’un paramètre de procédé. La quatrième partie établit la conclusion générale et trace les perspectives. / With the rise of global warming issues due to the increase of the greenhouse gas emission and more generally with growing importance granted to sustainable development, process system engineering (PSE) has turned to think more and more environmentally. Indeed, the chemical engineer has now taken into account not only the economic criteria of the process, but also its environmental and social performances. On the other hand LCA is a method used to evaluate the potential impacts on the environment of a product, process, or activity throughout its life cycle. The research here focused on coupling of PSE domain with the environmental analysis of agricultural and chemical activities and abatement strategies for agro-processes with the help of computer aided tools and models. Among many approaches, the coupling of PSE and LCA is investigated here because it is viewed as a good instrument to evaluate the environmental performance of different unitary processes and whole process. The coupling can be of different nature depending on the focus of the study. The main objective is to define an innovative LCA based on approach for a deep integration of product, process and system perspectives. We selected a PSE embedded LCA and proposed a framework that would lead to an improved eco-analysis, eco-design and eco-decision of business processes and resulted products for researchers and engineers. In the first place we evaluate biodiesel for environmental analysis with the help of field data, background data and impact methodologies. Through this environmental evaluation, we identify the hotspot in the whole production system. To complement the experimental data this hotspot (i.e. transesterification) is selected for further modeling and simulation. For results validation, we also implement LCA in a dedicated tool (SimaPro) and simulation in a PSE simulation tool (Prosim Plus). Finally we develop a tool (SimLCA) dedicated to the LCA by using PSE tools and methodologies. This development of SimLCA framework can serve as a step forward for determination of sustainability and eco-efficient designing.

Le biodiesel est un biocarburant, composé d'un mélange de mono-esters d'acide gras saturés et insaturés avec une longue chaîne carbonée. Ce travail de thèse présente les données de la littérature sur l'origine du biodiesel et son procédé de fabrication ; sont présentées aussi les performances et les émissions des moteurs diesel fonctionnant au biodiesel et la cinétique d'oxydation du biodiesel. Des efforts ont été faits pour mettre en évidence les principales différences entre les esters méthyliques et éthyliques tout en montrant que d'autres recherches sont encore à développer. Pour ces raisons, les délais d'auto-inflammation de cinq esters méthyliques et éthyliques ont été mesurés dans un tube à onde de choc : l'acrylate d'éthyle, l'acrylate de méthyle, le crotonate d'éthyle, le crotonate de méthyle et le butanoate d'éthyle. Les mécanismes cinétiques détaillés d'oxydation des cinq esters étudiés ont été générés automatiquement en utilisant le logiciel EXGAS. L'oxydation du butanoate d'éthyle, molécule modèle d'esters éthyliques d'huiles végétales (EEHV) a été étudiée dans un réacteur piston à pression atmosphérique pour une gamme de température allant de 500 à 1200 K. Les résultats représentent les profils de concentration des réactifs, les intermédiaires stables et les produits finaux. Le modèle cinétique a été validé de façon satisfaisante par une comparaison entre les résultats simulés et expérimentaux / An increasingly popular biofuel is biodiesel, composed of a mixture of saturated and unsaturated fatty acid methyl or ethyl esters, with a long aliphatic main chain. This PhD dissertation provides a literature review concerning the origin of biodiesel, its manufacturing process, performance and emissions of diesel engines fueled with biodiesel, and the kinetics of oxidation of biodiesel. Efforts were made to highlight the main differences between methyl and ethyl esters while showing where further research needs to be developed or pursued. For these reasons, the autoignition of five esters were measured behind reflected shock tube: ethyl acrylate, methyl acrylate, ethyl crotonate, methyl crotonate, and ethyl butanoate. Detailed mechanisms for the oxidation of the five studied esters were automatically generated using the version of EXGAS software. In addition, the oxidation of ethyl butanoate as a model compound for Fatty Acid Ethyl Esters (FAEE) has been investigated in tubular plug flow reactor at atmospheric pressure over wide range of temperature (500-1200 K). The results consist of concentration profiles of the reactants, stable intermediates, and final products. The model was again validated satisfactorily by comparison between computed results and the generated experimental data

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At present, the use of other sources of energy other than energy source from crude oil has accelerated. This is due to limited resources of fossil fuel, increasing prices of crude oil and environmental concerns. Alternative fuels such as biofuel are becoming more important because it can serve as a replacement for petroleum diesel due to its comparable fuel properties and cleaner emission. For use in a standard diesel engine, biodiesel can be blended (mixed) with petroleum diesel at any concentration. In this study, transesterification of waste cooking oil with methanol was catalyzed by heterogeneous catalyst TiO2-supported-MgO and the biodiesel produced was characterised. Waste cooking oil (WCO) was used because it is regarded as one of the cheapest feedstock for biodiesel production in that most oils from oil crops are used as food. Waste cooking oil is available in vast amounts each day in every restaurants and fast food outlets worldwide. The waste cooking oil used in this study was laboratory prepared by the addition of 5 wt. % of oleic acid into 95 wt. % of soybeans oil.10 wt. % of titanium-supported-magnesium oxide catalyst (MgO/TiO2) used was prepared by incipient wetness impregnation and characterized using XRF, BET and XRD. These materials were tested with the catalyst for the conversion of waste vegetable oil to biodiesel in presence of methanol and hexane co-solvent. Methanol to oil mole ratio of 18:1 was employed in the transesterification process. When hexane was used as cosolvent, methanol to oil mole ratio of 18:1 and methanol to hexane mole ratio of 1:1 was used. The effects of reaction time, reaction temperature and hexane co-solvent on the waste vegetable oil conversion has been established. The 1HNMR analysis was used to estimate the structure of FAME produced. It was observed that the oil conversion increases with the increased reaction time, reaction temperature and use of hexane as co-solvent. / Chemical Engineering / M. Tech. (Chemical Engineering)

En vue d’effectuer des préparations sélectives de composés hétérocycliques, une étude de la synthèse et de la réactivité de 7-oxanorborna-2,5-diènes portant des groupes électroattracteurs différents sur les positions 2 et 3 a été réalisée. Ces composés sont des formes masquées de composés acétyléniques dissymétriques.Dans un premier temps, nous avons optimisé une nouvelle méthode de synthèse sélective d’acétylènedicarboxylates dissymétriques par mono-transestérification d’acétylènedicarboxylates de dialkyle symétriques avec des alcools en présence de la lipase de Candida rugosa. Cette méthode nous a permis d’obtenir les diesters dissymétriques avec de bons rendements et une haute sélectivité a priori inattendue.Dans un second temps, nous avons développé des synthèses régiosélectives de dérivés de l’acide 7-oxanorborna-2,5-diène-2,3-dicarboxylique selon deux stratégies. Dans une première approche, une réaction de Diels-Alder intramoléculaire entre un furane et un composé acétylénique reliés par une agrafe siliciée a été réalisée, suivie d’une coupure des liaisons Si-C. Cette cycloaddition [4+2] s’effectue uniquement en présence de MeAlCl2 avec des rendements moyens. Dans certains cas, la coupure des liaisons Si-C conduit aux diesters désirés. Dans une deuxième approche, une mono-saponification d’oxanorbornadiène-2,3-dicarboxylates de dialkyle a permis d’accéder régiosélectivement à des monoacides et des réactions de couplage avec des amines ou des alcools ont conduit sélectivement à des dérivés présentant deux groupes électroattracteurs différents.Dans une dernière partie, nous avons effectué la préparation régiosélective de 3-pyrrolines par cycloaddition [2+3] d’un ylure d’azométhine suivie d’une réaction de rétro-Diels-Alder à partir des 7-oxanorbornadiènes comportant deux groupes électroattracteurs différents. La préparation aisée de 3-pyrrolines condensées non décrites dans la littérature a été obtenue par formation inattendue d’un motif succinimide dans le cas des amidoesters.En conclusion, il apparaît que la présence du groupe éthyle en tête de pont des 7-oxanorborna-2,5-diènes semble suffisante pour contrôler la régiosélectivité de ces cycloadditions. / In order to selectively prepare heterocyclic compounds, a study of the synthesis and reactivity of 7-oxanorborna-2,5-dienes with different electron-withdrawing groups on the 2 and 3 positions was performed. These compounds are masked forms of unsymmetrical acetylenic compounds. At first, we have optimized a new method for the selective synthesis of unsymmetrical diesters by transesterification of symmetrical dialkyl acetylenedicarboxylates in the presence of Candida rugosa lipase. This unexpectedly highly selective method allowed us to obtain unsymmetrical acetylenedicarboxylates in good yields.In a second part, we have developed a regioselective synthesis of 7-oxanorborna-2,5-diene-2,3-dicarboxylic acid derivatives according to two strategies. In one approach, an intramolecular Diels-Alder reaction between a furan and an acetylenic compound connected by silicon-containing tethers was performed, followed by a cleavage of the Si-C bonds. This [4+2] cycloaddition was carried in the presence of a Lewis acid, only MeAlCl2 gave the expected product and so in moderate yields. In most cases, the cleavage of Si-C bonds leads to the desired diesters. In a second approach, a mono-saponification of dialkyl oxanorbornadiene-2,3-dicarboxylates provided access regioselectively to mono-acids and coupling reactions with amines or alcohols selectively led to poly-functionalized products containing two different electron-withdrawing groups.In the last part, we have regioselectively prepared 3-pyrrolines by [2+3] cycloaddition of an azomethine ylide to 7-oxanorbornadienes bearing electroattracting groups followed by a retro-Diels-Alder reaction. An easy synthesis of previously unknown condensed 3-pyrrolines was obtained by formation of an unexpected succinimide pattern from amidoesters. In conclusion, it appears that the presence of an ethyl group on the bridgehead carbon atom of 7-oxanorborna-2,5-dienes seems sufficient to control the regioselectivity of these cycloadditions.