Polycarbonates are a type of engineering thermoplastic that have countless uses in modern society. Currently, the major industrial production of polycarbonates involves the polycondensation of a diol and phosgene or phosgene derivative. Though there are many advantages to this process, it creates large amounts of waste and requires dangerous chemicals in order to proceed. Over the past four decades, the coupling of CO_(2) and epoxides has grown into a viable, greener alternative for the production of select polycarbonates. The byproduct of this reaction, cyclic carbonates, also have use as polar, high boiling solvents. This dissertation will be divided into three parts. First, the coupling of indene oxide and CO_(2) to form poly(indene carbonate) and cis-indene carbonate will be discussed. Poly(indene carbonate) has the highest Tg yet reported for polymers derived CO_(2) /epoxides coupling, up to 138degreeC. Polycarbonate production requires the use of (salen)Co(III) catalysts and low temperatures, though some cyclic carbonate production is still observed. Selective production of poly(indene carbonate) has been achieved through the use of bifunctional cobalt(III) complexes. The effects of temperature and cosolvent choices on polymer production will be thoroughly discussed. Though polycarbonate is the kinetic product from the coupling of CO_(2) and epoxides, the thermodynamic product is cyclic carbonate. There are six potential mechanisms that yield this undesired byproduct, though there is limited research into which pathways are the most active during polymerization reactions. Temperature-dependent kinetic studies were performed to obtain the activation parameters for the direct, polymer-free coupling of cyclopentene oxide, indene oxide, 1,2-butylene oxide, and styrene oxide with CO_(2) utilizing (salen)CrCl/nBu_(4)NCl to yield their corresponding cyclic carbonates. Additionally, the metal-free backbiting of the singly-coupled styrene oxide/CO_(2) intermediate was simulated utilizing the halohydrin 2-chloro-1-phenylethanol. Finally, the coupling of cyclopentene oxide with carbon disulfide to yield poly[thio]carbonates and cyclic [thio]carbonates utilizing (salen)CrCl/PPNX will be discussed. In each reaction, scrambling of the oxygen and sulfur atoms in both the polymeric and cyclic product is observed. Long reaction times lead to increased amounts of [thio]ether linkages and therefore polymers with lower glass transition temperatures. Insights into both the coupling and scrambling mechanisms will be presented.

The biodegradability and when functionalised biocompatibility of aliphatic polycarbonates (APCs) makes them an attractive class of materials for biomedical applications such as tissue engineering scaffolds and drug-delivery carriers. One route to accessing a wide-range of well-defined and functional APCs is the controlled ring-opening polymerisation (ROP) of cyclic carbonates. In turn, these would ideally be prepared by the direct coupling of CO2 with diols to give water as the only by-product. In this way, the combination of CO2 and sugar-derived diols draws upon two natural renewable building blocks for the construction of polycarbonates that are anticipated to show good biocompatibility properties. Chapter 2 develops a simple and mild alternative to the traditional use of phosgene derivatives for the synthesis of six-membered cyclic carbonates from 1,3-diols and CO2. DFT calculations highlighted the need to lower both the CO2-insertion and ring-closing kinetic barriers to cyclic carbonate formation. Organic superbase, 1,8- diazabicyclo[5.4.0]undec-7-ene (DBU) enabled the formation of carbonate species at 1 atm CO2 pressure whereas, the introduction of a leaving group strategy lowered the cyclisation barrier. Mechanistic considerations suggested a kinetic preference for ring- closing via a nucleophilic addition-elimination pathway rather than a SN2-like intramolecular cyclisation. Chapter 3 applies the procedure with CO2 to the preparation of a novel monomer from natural sugar, ᴅ-mannose. ROP was carried out via an organocatalytic approach and a preference for head-tail linkages in the polycarbonate backbone indicated by NMR spectroscopy and supported by DFT calculations. Chapter 4 utilises CO2 to invert the natural stereochemistry of sugars and create a thymidine-based monomer. The thermodynamic parameters of the ROP with 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) catalyst are determined and the properties of the polycarbonates investigated to include preliminary cell attachment studies. Finally, chapter 5 details the synthesis of cyclic carbonates from 2- deoxy-ᴅ-ribose and the investigation into the different ROP behaviour of the α- and β- anomers. The ability to tune the polymer properties through copolymerisation with trimethylene carbonate (TMC) is also discussed.

Dans cette thèse, nous avons décrit de nouvelles méthodes pour la préparation de polymères et de produits chimiques à partir de ressources renouvelables:Premièrement, nous avons défini une nouvelle méthode de préparation de sulfonamides, utilisant des nitro-aromatiques et des sels de sulfinate de sodium, dans une solution aqueuse de bisulfite de sodium, en tant qu’agent réducteur non toxique. Le produit a été séparé par une simple filtration. La réaction montre une chimio-sélectivité complète, seuls les substrats nitro déficitaire en électrons sont réactifs. Cependant, et contrairement à la littérature, les sels de sulfinate de sodium aromatiques et aliphatiques se sont révélés réactifs dans nos conditions. De plus, nous avons utilisé cette méthode pour préparer de manière écologique le catalyseur de zinc décrit par Karamé et al. et utilisé pour la cycloaddition du dioxyde de carbone avec des époxydes, afin d'accéder aux monomères de polycarbonates pour la préparation de polyuréthane non isocyanate.Ensuite, nous avons étudié la préparation de bis-carbonate de mannitol à partir de mannitol, en utilisant le carbonate de diméthyle comme réactif et comme solvant. Le carbonate de glycérol a été utilisé comme co-solvant en raison de ses propriétés de solubilisation intéressantes. La possibilité de synthèse des monomères diamines entièrement renouvelables a également été étudiée en utilisant des derives des sucres comme la furfurylamine et le 5-méthylfurfural. Nous avons également etudier l’aminolyse du bis-carbonate du mannitol avec la furfurylamine à la température ambiante. De plus, nous avons comparé la stabilité de ce carbonate avec les monomères carbonates commerciaux en utilisant une analyse gravimétrique thermique.Enfin, nous avons préparé le diester de 4,4'-oxydipentanoate de diéthyle à partir de lévulinate d'éthyle par éthérification réductrice sans solvant, catalysée par du triflate de cuivre, en utilisant du tétraméthydisiloxane comme agent réducteur. En outre, nous avons prouvé que ce nouveau monomère était utilisable dans la préparation des polyesters et des polyamides, dans des conditions de polycondensation classiques, en utilisant le propane diol et l’hexaméthylène diamine comme monomères modèles / In this thesis, we describe new methods for the preparation of polymers and chemicals from renewable resources: First we have defined new method for the preparation of sulfonamides, using nitro aromatics and sodium sulfinate salts, in aqueous sodium bisulfite solution as a non toxic reducing agent. The product was separated by simple filtration and the reaction show full chemoslectivity, only electron poor nitro substrates are reactive. However, in contrast with the literature, aromatic and aliphatic sodium sulfinate salts were found reactive under our conditions. In addition, we have used this method to prepare, in a green way, the active zinc catalyst reported by Karamé et al. for the cycloaddition of carbon dioxide with epoxydes, in order to access to polycarbonates monomers for non-isocyanate polyurethane preparation.Then, we have investigated the preparation of high purity mannitol bis-carbonate from mannitol using dimethyl carbonate as a reagent and as a solvent. Glycerol carbonate was used as co-solvent due to its interesting solubilization properties. The possibility of the synthesis of fully renewable diamine monomers was also investigated using furfurylamine and 5-methylfurfural derivated from sugars. We have also uncovered its high reactivity toward uncatalyzed aminolysis with furfurylamine at room temperature. Furthermore, we have compared the stability of this carbonate with existing commercial monomers using thermal gravimetric analysis.Finally, we prepared the diethyl 4,4'-oxydipentanoate diester from renewable ethyl levulinate was prepared by solventless reductive etherification, catalyzed by copper triflate, using tetramethydisiloxane as safe and low-cost reducing agent. Besides, we have proved the usability of this new monomer in the preparation of sustainable polyesters and polyamides, under classical polycondensation conditions, using propane diol and hexamethylene diamine as model monomers

Com o aumento da consciência global sobre os riscos do Aquecimento do Planeta e de suas possíveis causas ficou claro que é necessário desenvolver ou adaptar processos industriais de maneira a aproveitar dejetos como o CO2. Dentre as formas de se aproveitar o CO2, destaca-se a ciclo-adição aos epóxidos, com a formação de ciclocarbonatos. A reação é tecnologicamente interessante, pois ciclocarbonatos possuem diversas aplicações como solventes polares apróticos, eletrólitos e matéria prima para compostos como purinas, carbamatos, glicóis, policarbonato e outros. Para que a reação ocorra em tempo e condições viáveis, há a necessidade de se trabalhar com catalisadores. Foram reportados muitos catalisadores ao longo dos anos. Dentre os catalisadores mais comumente utilizados, destacam-se os sais orgânicos. Porém o estudo sobre modelos cinéticos e mecanismo de reação ainda carecem de mais atenção. Desta forma este trabalho propõe-se a estudar esta parte, através de experimentos cinéticos, modelos teóricos e cálculos de química quântica. Para isto escolheu-se estudar a ação catalítica do brometo de 1-propil-4-azo-1-azôniobiciclo[2,2,2]octano (P-DABCO) frente a um catalisador bem descrito na literatura, o brometo de tetrapropilamônio (TPA). / Nowadays mankind are becoming more aware about Global Warming risks and its possible causes. With that in mind, it is necessary to develop or to adapt industrial processes to use some wastes like CO2. One of the best strategies to utilize CO2 is to convert it to cyclic carbonate through cyclic addition reaction to epoxides. This reaction is important because cyclic carbonates have other useful applications. For example, they can be used as polar aprotic solvents, electrolytes and as starting material for other compounds like purine, carbamates, glycols, polycarbonate, among others. However, the cyclic addition reaction must be catalyzed so as to get the desired product in short possible time and under soft conditions. Many catalysts have been reported in the literature that can be used for the cyclic addition reaction, with the organic salts being very common ones. Most of these reports focus on the efficiency of the catalyst and little attention has been paid to the reaction kinetics models and reaction mechanisms. Thus, we intend to study this part. For this purpose, we will do kinetics experiments, theoretical models and quantum chemistry calculation. The 1-alkyl-4-aza-1-azaniabicyclo[2.2.2]octyl bromide was chosen to this work and will be compared with tetrapropylammonium bromide that is known in the literature.

Cette thèse porte sur la conception de carbonates cycliques originaux et d’amines dérivés des huiles végétales dans le but de synthétiser des poly(hydroxyuréthane)s entièrement bio-sourcés. D’une part, deux voies d’accès à des amines dérivées d’acides gras utilisant des conditions douces ont été étudiées. La première consiste en l’oxydation sous air d’alcools aliphatiques en nitriles en présence de TEMPO supporté sur silice, suivi par une hydrogénation des dinitriles en diamines. Egalement, des diènes dérivés d’acides gras ont été couplés à la cystéamine via une chimie thiol-ène, permettant l’accès à des diamines aliphatiques bio-sourcées. D’autre part, des carbonates cycliques substitués à 5 chaînons ont été synthétisés à partir de dérivés d’acides gras et de glycérol, dans le but d’augmenter leur réactivité vis-à-vis de l’aminolyse. En insérant un groupement fonctionnel éther, thio-éther ou ester en position α ou β des carbonates cycliques, la réactivité de ces derniers vis-à-vis des amines a pu être ajustée. L’étude de la sélectivité, des réactions secondaires et de la catalyse de la voie carbonate/amine a été menée afin de mieux appréhender cette voie d’accès à des polyuréthanes sans isocyanates. Des poly(hydroxyuréthane)s entièrement oléo-sourcés ont été synthétisés avec succès, montrant des propriétés physico-chimiques contrôlables selon la structure des monomères. / In this thesis, vegetable oils were used as a platform to design original cyclic carbonates and amines with the goal to synthesize fully bio-based poly(hydroxyurethane)s. On the one hand, two routes to fatty acid-based amines were implemented in mild conditions. First, the oxidation of aliphatic alcohols into nitriles was performed under air in the presence of supported TEMPO on silica, followed by hydrogenation of nitrile compounds into corresponding amines. Second, thiol-ene chemistry was performed on unsaturated fatty acid substrates to design original aliphatic bio-based diamines. On the other hand, substituted 5-membered cyclic carbonates were designed from fatty acids and glycerol derivatives to enhance their reactivity towards aminolysis. By inserting ether, thio-ether or ester functionalities in α- or β-position of the cyclic carbonates, their reactivity towards amines could be tuned. Investigations on the selectivity, side reactions and catalysis of the carbonate-amine reaction were carried out to apprehend this route to non-isocyanate polyurethanes. Fully vegetable oil-based PHUs with tunable physico-chemical properties with respect to the monomer structures could be easily achieved.

Submitted by PPG Engenharia e Tecnologia de Materiais (engenharia.pg.materiais@pucrs.br) on 2018-12-03T15:52:09Z No. of bitstreams: 1 Dissertacao DANIELA MAFFI RODRIGUES.pdf: 1641622 bytes, checksum: 7201a3a551a602c84d3776d0f02f7399 (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-12-05T13:35:48Z (GMT) No. of bitstreams: 1 Dissertacao DANIELA MAFFI RODRIGUES.pdf: 1641622 bytes, checksum: 7201a3a551a602c84d3776d0f02f7399 (MD5) / Made available in DSpace on 2018-12-05T13:50:46Z (GMT). No. of bitstreams: 1 Dissertacao DANIELA MAFFI RODRIGUES.pdf: 1641622 bytes, checksum: 7201a3a551a602c84d3776d0f02f7399 (MD5) Previous issue date: 2018-07-27 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Carbon capture and storage (CCS) and carbon capture and utilisation(CCU) technologies has been pointed out as possibilities to mitigate the effects caused by the massiverelease of CO2 into the atmosphere. The use of CO2 in cycloaddition reactions toepoxides obtaining cyclic carbonates is an interesting possibility to reduce CO2emission. Cyclic carbonates are products of great applicability as solvents in the chemical industry and are used as raw material for a wide range of products. Meanwhile, the use of CO2 for a cycloaddition reaction requires a large amount of energy being necessary the use of catalysts in order to optimize such reactions. Poly (ionic liquids) (PIL) are alternative catalysts due its selective, recyclability and conversion. In this work, cellulosic poly(ionic liquids) (CPIL) obtained from rice husk were testedas heterogeneous catalyst. Cellulose extraction was carried out by chemical method. A chemical modification of the cellulose fibers was carried out by the treatment with citric acid and functionalization with 3 mmol of the ionic liquids BMIM Cl, TBAB, TBPB and BMPYRR to form CPIL-BMIM, CPIL-TBA, CPIL-TBP and CPIL-BMPYRR), without addition of solvents. Cyclo addition reactions were carried out with propylene and styrene oxides with different CO2 pressures(25, 30 and 40 bar) and temperatures (90, 110 and 120 ?C) for 6 h. The obtained product was characterized by gas chromatography (GC), Fourier Transform Infrared Spectroscopy(FTIR)and Nuclear Magnetic Resonance (1H NMR). The results showed better yields for CPIL-TBP and CPIL-TBA, whose values were 53.2% and 39% respectively for propylene carbonate and 67.3% for styrene carbonate using CPIL-TBP. When the ZnBr2 cocatalyst was used, there was an increase in the catalytic activity of these catalysts. For CPIL-TBP the yields were 71.4% for propylene carbonate and 78.7% for styrene carbonate. For CPIL-TBA the increase in propylene carbonate yield was 67.7%. / O uso das tecnologias de captura e armazenamento de carbono (CCS) e de captura utiliza??o do carbono (CCU) v?m sendo apontadas como possibilidades para mitigar os efeitos causados pela libera??o deliberada de elevadas concentra??es de CO2 na atmosfera. A utiliza??o do CO2 em rea??es de cicloadi??o em ep?xidos para obter carbonatos c?clicos vem se mostrando uma possibilidade interessante para reduzir a emiss?o de CO2 na atmosfera. Os carbonatos c?clicos s?o produtos de grande aplicabilidade como solventes na ind?stria qu?mica e s?o utilizados como mat?ria prima para uma vasta gama de produtos. Entretanto, o CO2 apresenta baixa reatividade tornando-se necess?rio o uso de catalisadores para otimizar tais rea??es. Os poli(l?quidos i?nicos) (PILs) v?m se mostrando como poss?veis catalisadores alternativos, demonstrando-se seletivos, recicl?veis e gerando consider?vel convers?o. Neste trabalho foram testados poli(l?quidos i?nicos) celul?sicos (CPIL), obtidos a partir da casca do arroz, como catalisador heterog?neo. A extra??o da celulose foi realizada por um m?todo qu?mico. A modifica??o qu?mica das fibras de celulose foi realizada a partir do tratamento com ?cido c?trico e a funcionaliza??o desta com 3 mmol dos l?quidos i?nicos BMIM Cl, TBAB, TBPB e BMPYRR formando CPIL-BMIM, CPIL-TBA, CPIL-TBP e CPIL-BMPYRR. As rea??es de cicloadi??o foram realizadas com os ?xidos de propileno e estireno com diferentes press?es de CO2 (15, 25, 30 e 40 bar) e temperaturas (90, 110, 120 e 130?C) durante (3, 6 e 9h), todas as rea??es foram realizadas sem a utiliza??o de solventes. O produto obtido foi caracterizado por cromatografia gasosa (CG) , espectroscopia de infravermelho com transformada de Fourier (FTIR) e Resson?ncia Magn?tica Nuclear (1H RMN). Os resultados demonstraram melhores rendimentos para CPIL-TBP e CPIL-TBA, cujos valores foram de 53,2% e 39% respectivamente para o carbonato de propileno e de 67,3% para o carbonato de estireno utilizando o CPIL-TBP. Quando o cocatalisador ZnBr2 foi utilizado, houve um aumento na a atividade catal?tica destes catalisadores, para o CPIL-TBP os rendimentos foram de 71,4 % para o carbonato de propileno e 78,7% para o carbonato de estireno. Para o CPIL-TBA o aumento no rendimento de carbonato de propileno foi de 67,7%.

Com o aumento da consciência global sobre os riscos do Aquecimento do Planeta e de suas possíveis causas ficou claro que é necessário desenvolver ou adaptar processos industriais de maneira a aproveitar dejetos como o CO2. Dentre as formas de se aproveitar o CO2, destaca-se a ciclo-adição aos epóxidos, com a formação de ciclocarbonatos. A reação é tecnologicamente interessante, pois ciclocarbonatos possuem diversas aplicações como solventes polares apróticos, eletrólitos e matéria prima para compostos como purinas, carbamatos, glicóis, policarbonato e outros. Para que a reação ocorra em tempo e condições viáveis, há a necessidade de se trabalhar com catalisadores. Foram reportados muitos catalisadores ao longo dos anos. Dentre os catalisadores mais comumente utilizados, destacam-se os sais orgânicos. Porém o estudo sobre modelos cinéticos e mecanismo de reação ainda carecem de mais atenção. Desta forma este trabalho propõe-se a estudar esta parte, através de experimentos cinéticos, modelos teóricos e cálculos de química quântica. Para isto escolheu-se estudar a ação catalítica do brometo de 1-propil-4-azo-1-azôniobiciclo[2,2,2]octano (P-DABCO) frente a um catalisador bem descrito na literatura, o brometo de tetrapropilamônio (TPA). / Nowadays mankind are becoming more aware about Global Warming risks and its possible causes. With that in mind, it is necessary to develop or to adapt industrial processes to use some wastes like CO2. One of the best strategies to utilize CO2 is to convert it to cyclic carbonate through cyclic addition reaction to epoxides. This reaction is important because cyclic carbonates have other useful applications. For example, they can be used as polar aprotic solvents, electrolytes and as starting material for other compounds like purine, carbamates, glycols, polycarbonate, among others. However, the cyclic addition reaction must be catalyzed so as to get the desired product in short possible time and under soft conditions. Many catalysts have been reported in the literature that can be used for the cyclic addition reaction, with the organic salts being very common ones. Most of these reports focus on the efficiency of the catalyst and little attention has been paid to the reaction kinetics models and reaction mechanisms. Thus, we intend to study this part. For this purpose, we will do kinetics experiments, theoretical models and quantum chemistry calculation. The 1-alkyl-4-aza-1-azaniabicyclo[2.2.2]octyl bromide was chosen to this work and will be compared with tetrapropylammonium bromide that is known in the literature.

Cette thèse porte sur la valorisation de dérivés d’acides gras dans l’objectif d’élaborer des matériaux polycarbonates aliphatiques (PCAs) bio-sourcés originaux. Dans cette optique, deux plateformes de carbonates cycliques à 6 chaînons (6CCs) ont été synthétisés en utilisant des voies d’accès impliquant soit la formation d’un intermédiaire de type malonate ou un couplage entre un acide gras et le 2-amino-1,3-propanediol. La polymérisation par ouverture de cycle de ces monomères a été étudiée. La première plateforme de 6CCs a été polymérisée en présence de Sn(Oct)2 comme catalyseur, donnant accès à des polycarbonates de faible Tg allant de -61°C jusqu’à-26°C du fait de longues chaines latérales pendantes. La polymérisation de la seconde plateforme de6CCs a été effectuée de manière contrôlée en utilisant un système catalytique composé de la DBU et d’une thio-urée. Tirant profit de ces polycarbonates aliphatiques bio-sourcés linéaires porteurs d’insaturations, des matériaux originaux réticulés ont été synthétisés. Plusieurs méthodes de réticulation ont été testées telles que le couplage thiol-ène irréversible, la réaction de Diels-Alder thermo-réversible et la cyclo-addition photo-réversible [2+2] entre deux groupements cinnamate.Ainsi, des PCAs réticulés issus d’acides gras ont été synthétisés et caractérisés; ces derniers possèdent des propriétés physico-chimiques modulables selon la nature des monomères de départ etla densité de réticulation des réseaux. / Fatty acids were derivatized with the objective to design bio-based aliphatic polycarbonate(APC) materials. To that purpose, two platforms of lipidic 6-membered cyclic carbonates were prepared following synthetic routes either involving the ring-closure of a malonate intermediate or the coupling reaction between a fatty acid and 2-amino-1,3-propanediol. The ring-openingpolymerization (ROP) of these cyclic carbonates was next investigated. The first platform of 6CCswas polymerized in the presence of Sn(Oct)2 as catalyst, yielding low Tg aliphatic polycarbonates ranging from -61°C to -26°C with respect to the size of the pendant aliphatic side chains. The polymerization of the second lipidic 6CC platform was performed in a controlled fashion using DBU/Schreiner thiourea as catalytic system. Taking advantage of the presence of unsaturation functions on the linear bio-based APCs, cross-linked polycarbonate materials were then prepared.Several cross-linking methods were tested such as the irreversible thiol-ene coupling, the thermoreversible Diels-Alder reaction and the photo-reversible [2+2] cyclo-addition reaction between two cinnamate moieties. Fatty acid-based cross-linked APCs were thus designed and characterized; the latter exhibit tunable physico-chemical properties as a function of the monomer structure and the cross-linking density.

Le développement de procédés catalytiques pour la valorisation chimique du dioxyde de carbone (CO2), suscite un intérêt grandissant en termes de chimie du carbone et de développement durable. Les travaux de cette thèse portent sur l’étude de la synthèse de carbonates cycliques à partir du couplage du CO2 avec des époxydes. De nombreux catalyseurs ont été développés dont les sels d’ammoniums fournissant le nucléophile nécessaire pour initier la réaction par ouverture de l’époxyde. Notre projet propose une nouvelle approche qui consiste à augmenter la nucléophilicité du catalyseur via une chimie hôte-invité dans laquelle des récepteurs moléculaires de type cavitands viennent sélectivement encapsuler les cations ammoniums, libérant ainsi l’anion nucléophile pour une meilleure réactivité. Notre système catalytique, testé à 1 bar de CO2, a notamment démontré tout son potentiel par l’activation accrue de sels de tétraméthylammonium initialement inactifs. Des expériences effectuées sous une pression de CO2 de 10 bar, ont permis d'étudier l’influence de la structure des cavitands et de montrer qu’une double activation était possible grâce à la conception de cavitands comportant des fonctions acides de Brönsted et des propriétés d’encapsulation optimales. Une application à la catalyse hétérogène a finalement été initiée par l’immobilisation des ammoniums ou des cavitands sur des supports à base de silice pour profiter des avantages de tels procédés. / The utilization of carbon dioxide (CO2) as a key component in organic transformations has recently drawn much attention as a greener alternative to fossil fuel based resources. The objectives of this work aim at studying the synthesis of cyclic carbonates from the coupling of CO2 with epoxide. Numerous catalysts have been proposed for this reaction among which the ammonium halides providing the nucleophile to initiate the reaction by opening the epoxide. Herein, we propose a new approach based on host-guest chemistry, to improve catalytic reactivity by increasing the nucleophilicity of the halide anion. For this purpose, cavitand molecular receptors able to bind quaternary ammonium ions are used, releasing the anionic nucleophile for the initial epoxide ring-opening reaction. At CO2 atmospheric pressure, our catalytic systems demonstrated a great potential by the dramatic activation of tetramethylammonium halides, whereas when used alone, these catalysts had never shown any activity. The influence of the cavitand structure was investigated through experiments run under 10 bar of CO2 pressure, and revealed that a double activation was possible with cavitand bearing Brönsted acidic hydroxyl functions and optimal recognition properties. The heterogeneization of such catalytic systems was finally studied with the grafting of either ammoniums or cavitands on silica based materials.

This thesis, largely describing diverse studies in organic synthesis, is divided into three parts. Part I, titled ‘Heterocycles’, describes in two chapters studies directed towards elaborating certain thiazole and oxazole derivatives as useful synthons. Part II, titled ‘Hydride transfers’, describes in two chapters synthetic and some mechanistic studies involving the Cannizzaro and Tishchenko reactions, apart from work with chirally-modified alumino and borohydride reagents. Finally, Part III, titled ‘Miscellaneous studies’, describes structural studies on cyclic carbonates. (For structural formula see the abstract.pdf file.)