L’objectif des travaux est de mieux comprendre durant la torréfaction de différentes biomasses l’évolution chimique à la fois des phases solide et gaz. Des expériences de torréfaction ont été menées selon un profil de température dynamique entre 200 et 300°C, sous atmosphère inerte, sur du pin, du frêne, du miscanthus et de la paille de blé. La perte de masse et la formation des espèces condensables ont été analysées par ATG-GCMS, et l’évolution chimique de la phase solide par RMN du solide 13C CP/MAS. Trente espèces condensables ont été détectées ; la moitié a été formée dans l’ensemble de la gamme de température explorée et un tiers l’a été par toutes les biomasses. Les principaux phénomènes qui semblent associés à la dégradation du solide sont la décristallisation de la cellulose, une sévère dégradation de l’hémicellulose, la dévolatilisation des groupes acétyles, la conservation des groupes méthoxys et la formation d’un résidu solide. Il a été par ailleurs montré que perte de masse et évolution chimique du solide n’étaient pas directement corrélées pour différentes biomasses. A partir de ces résultats expérimentaux, un modèle conceptuel a été développé pour décrire la dégradation de la biomasse. Trente réactions ont été associées aux trois constituants macromoléculaires principaux que sont la cellulose, l’hémicellulose et la lignine, respectivement représentées par deux sucres en C5 et C6 et par trois unités detype H, G et S. Ce modèle présente l’originalité de s’appuyer sur une description détaillée de ces deux derniers constituants et de prévoir la formation de seize espèces condensables, cinq gaz permanents et six formes de char solide, grâce à des réactions ayant un sens chimique et équilibrées d’un point de vue stoechiométrique. / The objective of the present work is to better understand chemical evolution of both solid and gaseous phases during torrefaction of various biomasses. Torrefaction experiments were carried out with a dynamic profile of temperatures between 200 and 300°C, under inert atmosphere, for pine, ash-wood, miscanthus and wheat straw. Mass loss and formation of condensable species were analyzed by TGA-GC-MS, and chemical evolution of solid phase was characterized by 13C CP/MAS solid-state NMR. Thirty condensable species could be detected; a half of these species were formed during the whole temperature range, and a third were formed by all biomass types. The main phenomena that occurred in solid phase were found to be decrystallization of cellulose, severe degradation of hemicellulose, devolatilization of acetyl groups, conservation of methoxyl groups and charring. It was also found that mass loss and chemical evolution of solid were not directly correlated for different biomasses. Based on the experimental results, a conceptual model was developed to describe biomass degradation duringtorrefaction. Thirty reactions were determined for the three major macromolecular constituents, namely cellulose, hemicellulose – represented by C5 and C6 sugars – and lignin – represented by H, G and S units. The main innovations of this model are in thedetailed approach of hemicellulose and lignin compositions, as well as in the prediction of sixteen condensable and five permanent species, and six forms of solid char, through chemically meaningful and stoichiometrically valid reactions.

O desenvolvimento desta tese foi direcionado ao estudo da química iônica, em fase gasosa, de alguns compostos organo-metálicos, como: Ge(OEt)4, Ti(i-Pro)4, BU3SnOMe, GeE4, GeMe4, SiMe4 e Me6Si2NH. Foram abordados vários aspectos da química iônica destes compostos desde o estudo dos seus processos de fragmentação, a reatividade de cátions e ânions derivados destes compostos, a fotodisssociação de espécies hipervalentes formadas a partir de reações de adição, e por último foram obtidos dados sobre a afinidade protônica de ânions derivados de germânio. Além disto, foram promovidas outras investigações experimentais destinadas á obtenção de informações sobre a estrutura de espécies hipervalentes e a análise de substâncias químicas desconhecidas contendo átomos de Ge. Os resultados obtidos em algumas investigações são conclusivos, e por isto em alguns casos não foi criada uma seção voltada exclusivamente para as conclusões. Mesmo assim, algumas observações podem ser destacadas. De modo geral, os alcóxidos metálicos reagem com íon fluoreto através de reações de adição-eliminação formando complexos pentacoordenados, que no caso dos derivados de germânio e titânio, absorvem radiação infravermelha de um laser de CO2, e por absorção multifotônica promovem sucessivos processos de eliminação de espécies neutras simples. O mesmo comportamento não é observado nas alquilas metálicas. Os cátions derivados destes compostos são poderosos ácidos de Lewis, e sofrem reações de adição-eliminação com diversos substratos neutros, do tipo base de Lewis. O mais surpreendente foi à observação de reações de abstração de ligantes como CH3- por alguns destes cátions, e a subseqüente formação, em alguns casos, de espécies formadas através de reações de troca de ligantes. A afinidade protônica de alguns ânions formados através da fotodissociação de espécies hipervalentes, derivadas de germânio, foi obtida por meio de reações de abstração de prótons com substratos de afinidade protônica conhecida. Foi possível caracterizar a acidez dos ácidos conjugados destes ánions como sendo próxima a das mercaptanas. / The present thesis describes the study of the gas-phase ion chemistry of a number of organometallic compounds such as Ge(OEt)4, Ti(i-Pro)4, BU3SnOMe, GeE4, GeMe4, SiMe4 and Me6Si2NH. Several aspects of the ion chemistry of these compounds were investigated including fragmentation processes in their mass spectra, reactivity of cations and anions obtained from these compounds by electron ionization, photodissociation of hypervalent species formed by nucleophilic addition, and the proton affinity of a number of germanium-containing anions. Additional experimental investigations were carried out to characterize the structure of hypervalent studies and to explore analytical applications of unknown germanium-containing substrates. The results in several cases are sufficiently conclusive such that a general section of conclusions was considered unnecessary. For example, the metal alkoxides studied in this work react with fluoride ion in the gas-phase by an addition-elimination mechanism that initially results in the formation of a pentacoordinated species. The germanium and titanium pentacoordinated species absorb readily infrared radiation from a CO2 laser and undergo successive elimination of sim pie neturals by sequential mutiphoton absorption. This behavior is not observed for the metal alkyls. Cations derived from these compounds are powerful Lewis acids and are capable of promoting addition-elimination reactions with several neutral substrates that can act as Lewis bases. The most surprising reactions have been the abstraction of methide (formally a CH3- ion) by some of these cations followed, in the case of some Si- and Ge-containing ions, by a ligand exchange reaction. The proton affinity of Ge-containing anions obtained from the photodissociation of hypervalent precursors was established using the bracketing technique by studying the proton abstraction reaction with a number of substrates of well-known proton affinities. The absolute values derived for the proton affinities of these species, and the corresponding gas-phase acidities of the conjugate acids are close to the values of similar mercaptans.

Ce travail porte sur la production de bio-huile par liquéfaction hydrothermale de résidus agroalimentaires, réalisée en réacteur batch. L’objectif est d’étudier l’influence des paramètres opératoires sur la production de bio-huile, et de contribuer à la compréhension des mécanismes de conversion hydrothermale de la biomasse. La liquéfaction hydrothermale des résidus agroalimentaires a été étudiée à partir de l’exemple des drêches de cassis, résidus de pressage des baies. Une étude paramétrique a évalué l’influence de la température, du temps de réaction, de la concentration de biomasse et de l’ajout d’hydroxyde de sodium sur le rendement des produits. Cette étude a permis d’identifier des conditions opératoires favorables à la production de bio-huile, dont le rendement peut notamment bénéficier du recyclage de la phase aqueuse en tant que solvant réactionnel (rendement maximal de bio-huile : 31 %). La caractérisation physico-chimique de la bio-huile montre que celle-ci possède certaines propriétés proches du pétrole brut et de certains fiouls lourds, notamment grâce à sa faible teneur en oxygène en comparaison des huiles de pyrolyse. La bio-huile peut être considérée comme un bio-pétrole brut, mais nécessite toutefois un raffinage conséquent avant de potentielles applications. La conversion hydrothermale de molécules modèles, sélectionnées à partir de l’analyse de la composition des drêches de cassis, a été étudiée à une température de 300 °C et un temps de réaction de 60 min. Cinq monomères modèles (glucose, xylose, acide glutamique, guaiacol et acide linoléique) et deux polymères modèles (cellulose microcristalline et lignine alkali) ont été choisis pour cette étude. Une méthodologie basée sur les plans d’expérience de mélange a été mise en œuvre, afin d’aboutir à la construction de schémas réactionnels, et à l’élaboration de corrélations modélisant les rendements des produits en fonction de la composition initiale des mélanges. L’analyse des produits montre que la conversion hydrothermale des résidus agroalimentaires résulte principalement de dégradations primaires et d’interactions binaires entre les composants de la biomasse. Les corrélations obtenues à partir des composés modèles permettent de décrire avec un bon accord les rendements des produits de conversion hydrothermale de mélanges modèles et de plusieurs résidus agroalimentaires : drêches de brasserie, marc de raisin et akènes de framboise. / This work presents a study of hydrothermal liquefaction of food processing residues using a batch reactor, to produce bio-oil. The objective is to study the influence of operating conditions on bio-oil production, and to contribute to the understanding of the reaction mechanisms occurring during hydrothermal conversion of biomass. Hydrothermal liquefaction of food processing residues was studied using blackcurrant pomace, a berry pressing residue, as an example. A parametric study evaluated the influence of temperature, holding time, biomass concentration and the use of sodium hydroxide as additive on the yields of products. This study allowed the identification of favorable operating conditions to produce bio-oil. The bio-oil yield can in particular benefit from recycling the aqueous phase as reaction solvent (maximum bio-oil yield: 31%). Physicochemical characterization of the bio-oil showed that it has some similarities with heavy crude oil and heavy oils, especially thanks to a lower oxygen content than pyrolysis oils. The bio-oil can be considered as a bio-heavy crude oil, but it still requires significant upgrading before any potential applications. Hydrothermal conversion of model molecules, selected from the characterization of blackcurrant pomace, was studied at a temperature of 300 °C and a holding time of 60 min. Five model monomers (glucose, xylose, glutamic acid, guaiacol and linoleic acid) and two model polymers (microcrystalline cellulose and alkali lignin) were chosen for this study. A mixture design of experiments methodology was followed, to combine reactivity studies with the elaboration of correlations describing the mass yields of products as a function of the initial mixture composition. Analysis of the products shows that hydrothermal conversion of food processing residues is mainly due to degradations of individual compounds and binary interactions between components of biomass. The correlations obtained from the model compounds describe with good accuracy the mass yields of the products from hydrothermal conversion of a model mixture and several food processing residues: brewer’s spent grains, grape marc and raspberry achenes.

Cyclooctyne and cycloocten-5-yne undergo, at room temperature, a 1,3-dipolar cycloaddition with dialkyl acetylenedicarboxylates 1a,b to generate furan-derived short-lived intermediates 2, which can be trapped by two additional equivalents of 1a,b or alternatively by methanol, phenol, water or aldehydes to yield polycyclic products 3b–d, orthoesters 4a–c, ketones 5 or epoxides 6a,b, respectively. Treatment of bis(trimethylsilyl) acetylenedicarboxylate (1c) with cyclooctyne leads to the ketone 7 via retro-Brook rearrangement of the dipolar intermediate 2c. In all cases, the products are formed with perfect atom economy.

<p>Although Cu-SSZ-13 zeolites are used commercially in diesel engine exhaust after-treatment for abatement of toxic NO_x pollutants via selective catalytic reduction (SCR) with NH₃, molecular details of its active centers and mechanistic details of the redox reactions they catalyze, specifically of the Cu(I) to Cu(II) oxidation half-reaction, are not well understood. A detailed understanding of the SCR reaction mechanism and nature of the Cu active site would provide insight into their catalytic performance and guidance on synthesizing materials with improved low temperature (< 473 K) reactivity and stability against deactivation (e.g. hydrothermal, sulfur oxides). We use computational, titration, spectroscopic, and kinetic techniques to elucidate (1) the presence of two types of Cu²⁺ ions in Cu-SSZ-13 materials, (2) molecular details on how these Cu cations, facilitated by NH₃ solvation, undergo a reduction-oxidation catalytic cycle, and (3) that sulfur oxides poison the two different types of Cu²⁺ ions to different extents at via different mechanisms. </p><p><br></p> <p> </p> <p>Copper was exchanged onto H-SSZ-13 samples with different Si:Al ratios (4.5, 15, and 25) via liquid-phase ion exchange using Cu(NO₃)₂ as the precursor. The speciation of copper started from the most stable Cu²⁺ coordinated to two anionic sites on the zeolite framework to [CuOH]⁺ coordinated to only one anionic site on the zeolite framework with increasing Cu:Al ratios. The number of Cu²⁺ and [CuOH]⁺ sites was quantified by selective NH₃ titration of the number of residual Brønsted acid sites after Cu exchange, and by quantification of Brønsted acidic Si(OH)Al and CuOH stretching vibrations from IR spectra. Cu-SSZ-13 with similar Cu densities and anionic framework site densities exhibit similar standard SCR rates, apparent activation energies, and orders regardless of the fraction of Z₂Cu and ZCuOH sites, indicating that both sites are equally active within measurable error for SCR. </p><p><br></p> <p> </p> <p>The standard SCR reaction uses O₂ as the oxidant (4NH₃ + 4NO + O₂ -> 6H₂O + 4N₂) and involves a Cu(I)/Cu(II) redox cycle, with Cu(II) reduction mediated by NO and NH₃, and Cu(I) oxidation mediated by NO and O₂. In contrast, the fast SCR reaction (4NH₃ + 2NO + 2NO₂ -> 6H₂O + 4N₂) uses NO₂ as the oxidant. Low temperature (437 K) standard SCR reaction kinetics over Cu-SSZ-13 zeolites depend on the spatial density and distribution of Cu ions, varied by changing the Cu:Al and Si:Al ratio. Facilitated by NH₃ solvation, mobile Cu(I) complexes can dimerize with other Cu(I) complexes within diffusion distances to activate O₂, as demonstrated through X-ray absorption spectroscopy and density functional theory calculations. Monte Carlo simulations are used to define average Cu-Cu distances. In contrast with O₂-assisted oxidation reactions, NO₂ oxidizes single Cu(I) complexes with similar kinetics among samples of varying Cu spatial density. These findings demonstrate that low temperature standard SCR is dependent on Cu spatial density and requires NH₃ solvation to mobilize Cu(I) sites to activate O₂, while in contrast fast SCR uses NO₂ to oxidize single Cu(I) sites. </p><p><br></p> <p> </p> <p>We also studied the effect of sulfur oxides, a common poison in diesel exhaust, on Cu-SSZ-13 zeolites. Model Cu-SSZ-13 samples exposed to dry SO₂ and O₂ streams at 473 and 673 K. These Cu-SSZ-13 zeolites were synthesized and characterized to contain distinct Cu active site types, predominantly either divalent Cu²⁺ ions exchanged at proximal framework Al sites (Z₂Cu), or monovalent CuOH+ complexes exchanged at isolated framework Al sites (ZCuOH). On the model Z₂Cu sample, SCR turnover rates (473 K, per Cu) catalyst decreased linearly with increasing S content to undetectable values at equimolar S:Cu molar ratios, while apparent activation energies remained constant at ~65 kJ mol^-1, consistent with poisoning of each Z₂Cu site with one SO₂-derived intermediate. On the model ZCuOH sample, SCR turnover rates also decreased linearly with increasing S content, yet apparent activation energies decreased monotonically from ~50 to ~10 kJ mol^-1, suggesting that multiple phenomena are responsible for the observed poisoning behavior and consistent with findings that SO₂ exposure led to additional storage of SO₂-derived intermediates on non-Cu surface sites. Changes to Cu²⁺ charge transfer features in UV-Visible spectra were more pronounced for SO₂-poisoned ZCuOH than Z₂Cu sites, while X-ray diffraction and micropore volume measurements show evidence of partial occlusion of microporous voids by SO₂-derived deposits, suggesting that deactivation may not only reflect Cu site poisoning. Density functional theory calculations are used to identify the structures and binding energies of different SO₂-derived intermediates at Z₂Cu and ZCuOH sites. It is found that bisulfates are particularly low in energy, and residual Brønsted protons are liberated as these bisulfates are formed. These findings indicate that Z₂Cu sites are more resistant to SO₂ poisoning than ZCuOH sites, and are easier to regenerate once poisoned. </p>

Le carbure de silicium est un matériau souvent employé comme matrice dans les composites thermostructuraux. Le précurseur classiquement utilisé pour son élaboration par dépôt/infiltration par voie gazeuse est CH3SiCl3. La thèse vise à évaluer le remplacement de ce précurseur par des précurseurs gazeux bi-sourcés de SiC où carbone et silicium sont apportés séparément.A partir du système SiHCl3/C3H8/H2, l’influence du débit total, de la température, de la pression totale et de (C/Si)gaz sont évaluées et comparées aux résultats obtenus avec le système CH3SiCl3/H2. La mesure in situ de la vitesse de dépôt permet de définir des lois cinétiques apparentes. L’analyse IRTF de la phase gazeuse indique que les évolutions des pressions partielles des différents produits stables sont corrélées avec les transitions cinétiques et les changements de composition du solide. Les simulations numériques de l’évolution de la phase gazeuse montrent une bonne corrélation avec les résultats expérimentaux et permettent de proposer des mécanismes homogènes et hétérogènes qui pourraient expliquer les écarts à la stoechiométrie du dépôt.L’étude de six précurseurs supplémentaires permet de mieux identifier le rôle des principales espèces en phase homogène et hétérogène, et notamment les précurseurs effectifs de dépôt. Enfin, l’étude de l’infiltration de matériaux poreux modèles révèle des améliorations significatives en termes d’homogénéité de vitesse de dépôt.Ainsi, des conditions propices à l’infiltration de carbure de silicium peuvent être obtenues en adaptant la réactivité de la phase gazeuse par la sélection de précurseurs initiaux et des chemins réactionnels qui en découlent. / Silicon carbide (SiC) is material of choice for the matrix of Ceramic Matrix Composites (CMC).CH3SiCl3/H2 mixtures are currently used as gas precursor for the synthesis of the CVI-SiC matrices.The present work considers the dual-source approach with two separate carbon and silicon precursorsmolecules.In the case of SiHCl3/C3H8/H2 mixture, systematic studies of total flow rate, temperature, total pressureand C/Si ratio of initial gaseous phase are realized. Kinetics obtained with growth rate measurements and solid composition are compared with results from CH3SiCl3/H2 mixture. On the basis of the apparent reaction orders and activation energies, experimental kinetic laws are derived. Through IRTF analysis of the gas phase, the partial pressures of the different stable products are correlated with deposition kinetic and solid composition. Results obtained in gas-phase kinetic simulation show a good correlation with the experimental results and a mechanism of homogeneous decomposition is proposed. A better understanding of the role of the principal species in homogenous and heterogeneous phase is obtained through the study of six other gas systems and the roles of some effective precursors are discussed. Finally, infiltration results of porous material models with different precursor systems reveal significant improvements as homogeneity of kinetic deposit.Hence, favourable conditions to silicon carbide infiltration can be obtained by adapting the reactivity of the gas phase, with the choice of initial precursors and homogeneous chemistry associated. Asystematic study of the process evidences promising working windows for the infiltration of pure SiCin porous performs.

Cette étude s’intéresse à l’amélioration des performances du laser solide Er3+:YAG, dont la longueur d’onde de 1,64 µm est dite « eye-safe ». L’une des solutions est le remplacement des monocristaux actuellement utilisés comme milieu amplificateur par des céramiques polycristallines Er:YAG transparentes, dont les propriétés thermomécaniques remarquables permettent une meilleure cohérence du faisceau de sortie et de ce fait, une augmentation des performances du laser. Cependant, la réunion des différents critères requis pour obtenir la transparence reste un réel challenge dans l’élaboration de ces céramiques. L’utilisation de poudres commerciales issues de deux voies de synthèse différentes a permis de souligner le rôle primordial des caractéristiques physiques de la poudre sur le comportement à la compaction et au frittage, effectué par Spark Plasma Sintering, tandis que la composition phasique et la pureté chimique conditionnent la qualité optique finale. Il ressort également que la coloration de la céramique observée lors du frittage résulte, non pas d’une contamination au carbone, mais de la formation de lacunes d’oxygène. Enfin, l’analyse et la compréhension du mode d’action du LiF utilisé comme aide au frittage ont permis d’établir des mécanismes réactionnels permettant d’optimiser le cycle de frittage. Cette démarche a conduit à l’obtention de céramiques polycristallines transparentes (Ø = 30 mm, e = 3 mm) à qualité optique élevée avec des valeurs de transmission de 80 % à 400 nm et 84 % à 1100 nm. Sur la base de ces résultats et de la simulation numérique, un changement d’échelle des céramiques (Ø = 50 mm, e = 5 mm) a été effectué dans le but de les évaluer en cavité laser. / This work focus on the improvement of the solid state Er3+:YAG laser performances presenting an "eye-safe" wavelength at 1.64 µm. One way is the replacement of single crystals currently used as gain media by polycrystalline ceramics as they present improved thermo-mechanical properties allowing a longer use of the laser. However, the meeting of different criteria requested to get transparency remains a challenge in the development of these ceramics. The use of commercial powders produced by two different synthesis ways allowed to highlight the essential role of the physico-chemical characteristics of the powder on compaction and sintering behaviors, performed by Spark Plasma Sintering, Phase composition and chemical purity have an influence of the final optical quality. It was also figured out that the gray coloration of the ceramic observed after sintering is caused by the formation of oxygen vacancies, rather than a carbon contamination. Finally, the mode of action of LiF, used as sintering aid to increase optical transmittance, was studied in order to establish reaction mechanisms allowing an optimization of the SPS cycle. This approach helps to reach Er3+:YAG transparent polycrystalline ceramics (Ø = 30 mm, thk = 3 mm) with an optical transmittance of 80 at 400 nm and 84 % at 1100 nm. On the basis of these results and with the help of numerical simulation, an up-scaling of ceramics (Ø = 50 mm, thk = 5 mm) was undertaken in order to evaluate their laser performances through laser cavity tests.

La present tesi doctoral s'ha basat en la caracterització estructural i en l'estudi de les propietats catalítiques de nous complexos de pal·ladi(0) amb lligands olefínics contenint unitats de ferrocè. En una primera fase s'ha desenvolupat la síntesi d'estructures de tipus (E, E, E)-1,6,11-trisarilsulfonil-1,6,11-triazaciclopentadeca-3,8,13-triè contenint des d'una fins a tres unitats de ferrocè i s'ha estudiat la seva complexació amb pal·ladi(0). Mitjançant estudis electroquímics s'ha avaluat la seva possible aplicació en el reconeixement molecular electroquímic. Encara que aquest tipus d'estructures no han resultat vàlides per aquest tipus de processos de reconeixement, l'estudi electroquímic ha permès determinar que la presència del grup ferrocenil influeix en les propietats redox del metall complexat. S'ha descrit també l'obtenció de macrocicles pentaolefínics anàlegs de 25 membres contenint unitats de ferrocè i s'ha estudiat paral·lelament la seva complexació amb pal·ladi(0).En una segona part del treball s'han avaluat les propietats catalítiques del complex (E, E, E)-6,11-bis[(p-metilfenil)sulfonil]-1-ferrocenilsulfonil-1,6,11-triazaciclopentadeca-3,8,13-trièpal·ladi(0), en reaccions clàssicament catalitzades per pal·ladi tals com l'acoblament creuat de Suzuki o la reacció de Heck, i s'ha pogut determinar que és un catalitzador actiu en aquest tipus de reaccions, essent a més possible, la seva recuperació i reutilització. En el cas concret de la reacció de Heck s'han emprat sals de diazoni com a agents arilants i cal destacar que s'ha descrit el primer sistema catalític recuperable i reutilitzable per aquest tipus de reaccions. Mitjançant espectrometria de masses amb ionització per electrospray ha estat possible determinar el rol mecanístic del nostre complex de pal·ladi en la reacció de Heck amb sals de diazoni.Finalment, en una tercera part estructural del treball s'ha estudiat el comportament espectroscòpic dels complexos de pal·ladi(0) anteriorment mencionats, contenint des de tres unitats aríliques iguals fins a tres unitats aríliques diferents. Mitjançant RMN i difracció de raigs-X s'ha determinat que la complexitat estereoquímica dels complexos deriva dels isòmers que es poden formar mitjançant complexació del metall amb cada una de les cares dels tres dobles enllaços continguts a l'estructura. / The present work has been directed towards the structural characterization and the catalytic activity evaluation of new olefinic macrocyclic palladium(0) complexes containing ferrocene units.The synthesis of 15-membered macrocycles, namely (E, E, E)-1,6,11-trisarylsulfonyl-1,6,11-triazacyclopentadeca-3,8,13-triene, containing from one to three ferrocenyl units has been described and its complexation ability towards palladium(0) has been demonstrated. By studying the electrochemical behaviour of the synthesized macrocyclic ligands and their palladium(0) complexes, it has been shown that they do not have application in electrochemical recognition of palladium(0). This electrochemical study has evidenced, though, that the ferrocenyl group is strongly influencing the palladium redox properties. The synthesis of analogous 25-membered pentaolefinic macrocycles containing ferrocene has also been described. Furthermore, a palladium(0) complex of this 25-membered macrocycle has been isolated and characterized by NMR and electrospray ionization mass spectrometry.On the other hand, the catalytic activity of the palladium(0) complex (E, E, E)-6,11-bis[(p-methylphenyl)sulfonyl]-1-ferrocenylsulfonyl-1,6,11-triazacyclopentadeca-3,8,13-trienepalladium(0), has been studied. Our catalyst has shown to be active in Suzuki type cross-couplings and in the Heck reaction, and furthermore, its recovery and reuse has proved to be feasible. Of great importance is the fact that our palladium-triolefinic macrocyclic complex is the first recoverable catalyst described in Heck reaction with arenediazonium cations. Electrospray ionization mass spectrometry has been used as the tool for investigating the mechanistic role of the palladium(0) complex in the Heck reaction.Finally, the spectroscopic behaviour of the formerly mentioned triolefinic palladium(0) complexes containing from one to three aryl units has been studied. By means of NMR and X-ray diffraction, it has been proved that the stereochemical complexity is connected to the different isomers that can be formed by complexation of the metal to one or the other face of each of the three olefins involved.

Ce manuscrit est consacré à l’étude et au développement de microsystèmes capteurs de gaz sélectifs au dioxyde d’azote, destinés au contrôle de la qualité de l’air atmosphérique. La stratégie que nous avons développée consiste à associer une structure sensible à base de matériaux semi-conducteurs partiellement sélectifs aux gaz oxydants et des filtres sélectifs à l’ozone. L’objectif premier est la mise en oeuvre et la caractérisation de matériaux chimiques strictement imperméables à l’ozone (O3) et non-réactifs vis-à-vis du dioxyde d’azote (NO2). Notre choix s’est focalisé sur un matériau moléculaire, l’indigo, connu pour sa réactivité vis-à-vis de O3, et plusieurs nanomatériaux carbonés. Pour ces derniers, la possibilité de conformer leurs textures, leurs morphologies et leurs chimies de surface par traitements thermiques, chimiques et mécaniques, permet d’étendre le panel de matériaux potentiels et d’identifier les facteurs d’influence de leur réactivité avec les espèces gazeuses. La caractérisation de l’ensemble de ces matériaux a nécessité l’utilisation de techniques adaptées et complémentaires (adsorption de N2 à 77 K, spectroscopies Raman, XPS, IR en mode ATR, RPE et NEXAFS). Les filtres chimiques les plus efficaces (hauts rendements de filtration et grande durabilité) ont été sélectionnés d’après des tests de soumission aux gaz selon une méthodologie adaptée. Enfin, l’association de ces meilleurs filtres et de la structure capteur a conduit à l’élaboration de prototypes microsystèmes capteurs de gaz optimisés. De plus, une contribution à la compréhension des mécanismes d’interaction de l’indigo et de certains nanocarbones avec O3 et NO2 a aussi permis d’améliorer le microsystème en développant des méthodologies pertinentes et innovantes mais également en réalisant la synthèse de nouveaux filtres indigo / nanocarbone. / This work is devoted to the study and the development of gas sensors microsystems highly selective to nitrogen dioxide, dedicated to the air quality control. The strategy developed consists in the implementation of a sensitive structure based on semiconductor materials partially selective to oxidizing gases associated to an ozone selective filter. The first objective is the development of chemical filters strictly impervious to ozone (O3) and non-reactive towards the nitrogen dioxide (NO2). We have chosen a molecular material, indigo, well-known for its reactivity towards O3, and several carbonaceous nanomaterials. For these one, the possibility to modify their textures, their morphologies and their surface chemistries by chemical, mechanical and thermic treatments, enables us to extend the range of potential materials and to identify the factors of influence on their reactivity with gaseous species. The characterization of all these materials required the use of appropriate and complementary techniques (N2 adsorption at 77 K, Raman, XPS, IR in ATR mode, EPR and NEXAFS). The more efficient filters (high filtering yield and life-time) have been selected by means of specific tests of gas exposure. Finally, the association of the best filter and the sensitive structure has led to the development of optimized gas sensors microsystems prototypes.

Cyclooctyne and cycloocten-5-yne undergo, at room temperature, a 1,3-dipolar cycloaddition with dialkyl acetylenedicarboxylates 1a,b to generate furan-derived short-lived intermediates 2, which can be trapped by two additional equivalents of 1a,b or alternatively by methanol, phenol, water or aldehydes to yield polycyclic products 3b–d, orthoesters 4a–c, ketones 5 or epoxides 6a,b, respectively. Treatment of bis(trimethylsilyl) acetylenedicarboxylate (1c) with cyclooctyne leads to the ketone 7 via retro-Brook rearrangement of the dipolar intermediate 2c. In all cases, the products are formed with perfect atom economy.