Dissertations / Theses on the topic 'Homogeneous Reactions'

BDTBPMB has been proven to be an essential ligand in carbonylation chemistry. Its two tert-butyl groups and wide bite angle give it the ideal characteristics for this kind of chemistry, and leads to high activity and selectivity with use of its complexes. During this work the group of reactions where this ligand has been proven to be active has been extended with two new protocols for hydroxycarbonylation and aminocarbonylation. In the hydroxycarbonylation process, a large variety of unsaturated compounds were studied. Dioxane was found to be the ideal solvent, due to its properties in terms of coordinability, and miscibility with water. Using this solvent as the medium, a BDTBPMB complex of palladium was found to be highly active and selective under mild conditions. Initial attempts to address the aminocarbonylation of alkenes catalysed by the Pd/BDTBPMB system did not give high activity. This problem was overcome by the addition of an arylalcohol. Under those conditions, high selectivity and conversion was obtained in a wide variety of amides. However, attempts to address the aminocarbonylation of alkenes with ammonia gas to generate primary amides did not result in any conversion. The generation of these primary amides was obtained with transamidation of N-phenylnonamides which can be prepared by aminocarbonylation. Amides have been successfully hydrogenated to amines catalysed by a Ru/Triphos system. This system has been proven to be highly active in this reaction. High selectivities have been obtained in the generation of secondary amine. However, initial results of the hydrogenation of primary amides resulted in no formation of primary amines. A careful analysis of the mechanism of the formation of various products from the hydrogenation of primary amides allows the selective formation of primary amines by the ruthenium/Triphos system in the presence of ammonia. The possibility of the generation of primary amides in situ from acids under hydrogenation conditions, giving primary amines was explored with high conversion and moderate selectivities. To complete this work, a system based on a palladium complex for the decarboxylation of benzoic acids was developed. Usually, the decarboxylation reactions catalysed by copper require high temperatures. However, palladium complexes of highly electron donating ligands such as BDTBPMB or P([superscript]tBu)₃ were found to be highly active under milder conditions. This catalytic system was proven to be active in desulfonation reactions giving high conversion.

Reaction progress kinetic analysis (RPKA) is a powerful tool for determining kinetic parameters of catalytic reactions. Many of the published articles that have used RPKA have employed reaction calorimetry for obtaining sufficient data to be reliable. The use of gas uptake measurements, in place of calorimetry is explored in this Thesis. Chapter 2 details the use of gas uptake measurements in establishing the order with respect to substrate and gas for the rhodium catalysed hydrogenation of 1-octene. Previous studies have used initial rate measurements to establish these orders and the reaction cycle is well known. The use of RPKA allows the same information to be established in two reactions. Chapter 3 focuses on the rhodium catalysed hydroformylation of 1-octene as it involves the reaction of one substrate with two gases. Using RPKA it is possible to determine the order in substrate and the overall order in gas, but it was found difficult to determine the order with respect to the individual gases using RPKA alone. Chapter 4 shows the palladium catalysed methoxycarbonylation of vinyl acetate. The reaction has two substrate concentrations changing simultaneously as well as a gas. This chapter shows that by careful design of experiments the orders with respect to each of these substrates and CO can be determined in minimal numbers of experiments. Chapter 5 focuses on the methoxycarbonylation of alkynes, which uses RPKA in complex multistep reactions, to establish if RPKA can be used to determine the kinetics with respect to the individual reacting components for each step. This study focuses on the methoxycarbonylation of phenylacetylene to produce methyl cinnamate as well as the methoxycarbonylation of both terminal and internal linear alkynes. These linear alkynes carbonylate to produce an α,β-unsaturated ester. The double bond is isomerised from its conjugated position along the chain to the terminal position where it is trapped and carbonylated to produce an α,ω-dieter product.

The conversion of ethene, carbon monoxide and water to propanoic acid by the catalytic action of various rhodium species, was investigated by infra-red spectroscopy and autoclave batch reactions. Utilisation of a high pressure infra-red cell and a Fourier Transform infra-red spectrometry enabled study of the spectra of the catalytic systems at temperatures up to 180ºC, and at pressures of 10 -150 bar. The batch autoclave reactions enable rates, yield and selectivities to be determined with the aid of Gas Chromatography and Mass Spectroscopy. Rhodium halides were used as precursors and the effects of solvents, water, iodide initiators, were studied. It was shown that polar solvents favoured hydrocarbonylation as did hydrous conditions. Ethyl iodide and hydrogen iodide were active initiators, however hydrogen iodide was observed to poison the catalyst forming [Rh(CO)(_2)I(_4)](^-) and other rhodium(III) species. At temperatures above 170ºC rhodium(I) species such as [Rh(CO)(_2)I(_2)](^-) were more prominent. A novel catalyst system was produced by employing rhodium(III) chloride, tin(II) chloride and hydrochloric acid. The nature of this system was studied in terms of solvents, the interaction of rhodium and tin, and the role of hydrogen chloride. Infrared studies revealed rhodium-tin species in the reaction media. Studies were conducted to ascertain the role of cations and additives. Further studies determined the activity of other metals as co-catalysts to rhodium, showing tin to be a superior co-catalyst.

Magnetic field effects (MFE) on electrochemical systems have been of interest to researchers for the past 60 years. MFEs on mass transport, such as magnetohydrodynamics and magnetic field gradients effects are reported, but MFEs on electron transfer kinetics have been rarely investigated. Magnetic modification of electrodes enhances electron transfer kinetics under conditions of high concentrations and low physical diffusion conditions, as shown by Leddy and coworkers. Magnetic microparticles embedded in an ion exchange polymer (e.g., Nafion) applied to electrode surfaces. Rates of electron transfer reactions to diffusing redox probes and to adsorbates are markedly enhanced. This work reports MFEs on hydrogen evolution on illuminated p-Si; MFEs on hydrogen evolution on noncatalytic electrodes; a model for MFEs on homogeneous self-exchange reactions; and a convolution based voltammetric method for film modified electrodes. First, a MFE on the photoelectrochemical hydrogen evolution reaction (HER) at p-Si semiconductors is demonstrated. The HER is an adsorbate reaction. Magnetic modification reduces the energetic cost of the HER by 400 - 500 mV as compared to Nafion modified electrodes and by 1200 mV as compared to unmodified p-Si. Magnetically modified p-Si achieves 6.2 % energy conversion efficiency. Second, from HER on noncatalytic electrodes, the MFE on photoelectrochemical cells arises from improved heterogeneous electron transfer kinetics. On glassy carbon electrodes, magnetic modification improves heterogeneous electron transfer rate constant, k₀,for HER 80,000 fold. Third, self exchange reaction rates are investigated under magnetic modification for various temperatures, outersphere redox probes, and magnetic particles. Arrhenius analyses of the rate constants collected from the experiments show a 30 - 40 % decrease in activation energy at magnetically modified electrodes. A kinetic model is established based on transition state theory. The model includes pre-polarization and electron nuclear spin polarization steps and characterizes a majority of the experimental results. Lastly, a convolution technique for modified with uniform films electrodes is developed and coded in Matlab (mathematical software) for simple and straightforward analysis of Nafion modified electrodes.

Thesis (Ph. D.)--University of New Orleans, 2005.
Title from electronic submission form. "A dissertation ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry"--Dissertation t.p. Vita. Includes bibliographical references.

Most of the different homogeneous reactions catalyzed by gold have been developed in the past fifteen years and stem from the ability of both Au(I) and Au(III) complexes to coordinate and activate multiple carbon-carbon bonds. However, the high ionization potential of gold has long hindered Au(I)/Au(III) catalytic cycles under homogeneous conditions, an underdeveloped field compared to classical cross-coupling methodologies. Although direct evidence for the main elementary steps of organometallic chemistry has been obtained very recently, their scope is still limited and much remains to be done before our knowledge on gold reaches that of other transition metals, especially of groups 9 and 10. Therefore, the unifying motivation behind the different research topics presented in this doctoral dissertation is to enhance our expertise concerning the factors governing the reactivity of gold complexes, with oxidative addition and migratory insertion particularly under the spotlight
La majoria de reaccions homogènies catalitzades per or han estat desenvolupades els darrers quinze anys, i aprofiten la capacitat dels complexes d’Au(I) i Au(III) per coordinar i activar enllaços múltiples carboni-carboni. No obstant l'elevat potencial de ionització de l’or ha privat l’accés a cicles catalítics del tipus Au(I)/Au(III) en condicions homogènies, un camp subdesenvolupat en comparació amb d’altres metodologies d’acoblament creuat clàssiques. Malgrat que recentment els processos fonamentals en química organometàl·lica han estat evidenciats, el seu abast és encara limitat i queda molt per recórrer abans que el nostre coneixement en or assoleixi el d’altres metalls de transició. Així doncs, la motivació principal rere els projectes de recerca presentats en aquesta tesi doctoral és incrementar la nostra expertesa pel que fa als factors que governen les reactivitat dels complexes d’or, amb especial incidència en l’addició oxidant i la inserció migratòria

This thesis is concerned with the preparation of regiospecifically labelled compounds by homogeneous metal catalysed hydrogen isotope exchange reactions. The features of homogeneous hydrogen isotope exchange reactions are discussed in Chapter 1, along with other exchange methods; acid, base, heterogenous metal, radiation, enzymic and zeolite catalysis. In Chapter 2, homogeneous rhodium trichloride is investigated for regiospecificity of tritium labeling in a wide range of aromatic compounds. High regiospecificity of labelling ortho to carboxyl, carboxamide and methanamide groups is found, with the regiospecificity determined by 3H nmr spectroscopy. Also discussed is a study to determine whether any other Group VIII metal complexes will catalyse the ortho tritiation of benzoic acid, in addition to rhodium trichloride. The results of detritiation studies performed on benzoic acids using ruthenium acetylacetonate as catalyst as a model for rhodium trichloride are presented in Chapter 3, A possible reaction mechanism is also presented. Finally, an application of the rhodium trichloride system to the labelling of biologically useful molecules is discussed in Chapter 4. The deuteration and tritiation of a number of drugs and metabolites containing known ortho directing groups is described. In a large number of cases, the regiospecificity for ortho labelling is very high.

El objetivo general de esta tesis es establecer una ruta sintética para la inmovilización de organocatalizadores en soporte polimérico. En primer lugar, describimos el desarrollo de α,α-difenylprolinol metil/trimetilsilil éteres soportados en poliestireno (PS) a través de cicloadiciones azida-alquino catalizadas por cobre (CuAAC). Además, se tratará la preparación de tiourea homogéneas derivadas de prolina, asi como organocatalizadores de tipo squaramida y tiourea soportados en poliestireno para su uso en catálisis se enlace de hidrojeno. La formación y la aplicación de éteres de diarilprolinol inmovilizados PS se probó con éxito en reacciones de tipo Michael. Asimismo, se estudió la actividad y selectividad de tioureas bifuncionales derivadas de prolina en la reacción anti-Mannich enantioselectiva y se obtuvieron selectividades moderadas. La fácil preparación del organocatalizador de tipo squaramida soportado en PS dio lugar a, actividades y enantioselectividades elevadas en reacciones de adición de Michael. Además, todas las ventajas de los catalizadores inmovilizados sobre soporte sólido, como el reciclaje y aplicaciones de flujo continuo se han realizado con éxito. Al mismo tiempo, una tiourea organocatalitica soportada en PS ha sido elaborada con un enfoque adaptado a partir de la síntesis de la squaramida relacionada. Esta tiourea se utilizó en la reacción de α-aminación junto con la propia squaramida, proporcionando resultados de buena a moderados en la α-hydrazination de compuestos 1,3-dicarbonílicos. Por lo tanto, hemos sido capaces de desarrollar organocatalizadores soportados sobre polímero eficaces que han sido utilizados en aplicaciones de reciclaje y de flujo continuo con éxito.
The general aim of this thesis is to establish a synthetic route for the immobilization of organocatalysts onto polymer support. In this work, firstly we describe the development of polystyrene-supported diarylprolinol ethers via copper-catalyzed azide alkyne cycloaddition reaction, additionally, homogeneous proline derived thiourea organocatalyst and finally, polystyrene supported hydrogen bonding squaramide and thiourea organocatalysts. The formation and application of PS-supported diarylprolinol ethers was demonstrated successfully in Michael-type reactions. Then we continued with H-bonding homogeneous organocatalysts, proline derived bifunctional thiourea organocatalysts tested in enantioselective anti-Mannich reactions. In the last part, a facile preparation of PS-supported squaramide organocatalyst was successfully demonstrated, high catalytic activities and enantioselectivities obtained in the Michael addition reactions. Furthermore, all the advantages of solid supported catalysts such as recycling, and continuous flow applications have been performed with success. At the same time, the PS-supported thiourea organocatalyst was prepared with an approach adapted from the synthesis of squaramide organocatalyst. This thiourea was used in the α-amination reaction together with squaramide organocatalyst, good to moderate results were obtained in the α-hydrazination of 1,3-dicarbonyl compounds. Therefore, we have been able to develop effective polymer-supported organocatalysts and used them in the recycling and continuous flow applications successfully.

The first part of the thesis covers the development and utilization of electronically modified (pentaarylcyclopentadienyl)Ru-complexes in the racemization of secondary alcohols. This study revealed that the electronic properties of the substrate were the main factors dictating whether β-hydride elimination or hydride re-addition becomes the rate-determining step of the racemization process. With this knowledge in hand, it proved to be possible to design more efficient racemization protocols by matching the electronic properties of catalyst and substrate. The second part describes mechanistic work that aimed at elucidating the role of CO dissociation in the mechanism of secondary alcohol racemization catalyzed by a (pentaarylcyclopentadienyl)Ru-complex. From CO exchange studies, we demonstrated that CO dissociation occurred in the catalytically active tert-BuO-species as well as in the chloride precatalyst. Furthermore, an inhibition study showed that an increase of the partial pressure of CO had a negative influence on the racemization rate. Together, these two observations provide strong support for CO dissociation as a key step in the racemization of secondary alcohols. The third part concerns the improved synthesis and characterization of a heterogeneous catalyst consisting of Pd nanoparticles immobilized on aminopropyl-functionalized siliceous mesocellular foam. The developed Pd nanocatalyst was found to be a highly efficient and recyclable catalyst for the aerobic oxidation of a wide range of primary and secondary alcohols to the corresponding aldehydes and ketones. The fourth part deals with the successful application of the Pd nanocatalyst in chemically-induced H2O oxidation, when using either ceric ammonium nitrate or [Ru(bpy)3]3+ as the terminal oxidant. Remarkably, the Pd nanocatalyst proved to catalyze this reaction with high efficiency and the measured TOF was found to greatly exceed those of current state-of-the-art metal oxide catalysts. The fifth and final part describes the co-immobilization of Pd nanoparticles and the enzyme Candida Antarctica Lipase B into the same cavities of mesocellular foam, to generate a “metalloenzyme-like” hybrid catalyst for the dynamic kinetic resolution of a primary amine. The close proximity of the two catalytic species led to an enhanced cooperativity between them and resulted in an overall more efficient tandem process.

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 4: Manuscript. Paper 5: Epub ahead of print.

La gran quantitat de fluorocarbons a la natura i la seva estabilitat a animat a la comunitat científica a trobar noves metodologies per trencar l'enllaç C-F d'aquest compostos. D'aquesta manera, aquest flurorocarbons poden ser utilitzats com a reactius a la síntesi orgànica. L'estabilitat dels fluorurs d'aril es dona per la força de l'enllaç C-F, que és l'enllaç simple més fort de la natura. Aquesta és la seva principal característica i la raó de la seva poca reactivitat. Per aquest motiu, es desafiant per la comunitat científica trobar la manera per trencar l'enllaç C-F. De la mateixa manera l'enllaç C-O te característiques molt similars a les del C-F i per això, s'ha utilitzat com a alternativa per evitar residus fluorats. Aquesta Tesi tracta de l'estudi computacional del trencament d'enllaços C-F y C-O mitjançat borilacions i catalitzades per un catalitzador de níquel. Concretament, s'ha estudiat tres reaccions diferents, les hem comparades i trobat els punts en comú de les tres reaccions.
La gran cantidad de fluorocarbonos en la naturaleza y su estabilidad a animado a la comunidad científica a buscar nuevas metodologías para la rotura del enlace C-F de estos compuestos. De esta manera, estos fluorocarbonos pueden ser utilizados como reactivos en la síntesis orgánica. La estabilidad de los fluoruros de arilo se da por la fuerza del enlace C-F, que es el enlace simple más fuerte de la naturaleza. Ésta es su principal característica y la razón de su poca reactividad. Por este motivo, es desafiante para la comunidad científica encontrar la manera de romper el enlace C-F. De la misma forma el enlace C-O tiene características muy similares a las del C-F y por esto, se ha utilizado como alternativa para evitar residuos fluorados. Esta Tesis trata del estudio computacional de la ruptura de los enlaces C-F y C-O mediante borilaciones y catalizadas por un catalizador de níquel. Concretamente, se ha estudiado tres reacciones diferentes y las hemos comparado y buscado sus puntos en común.
The large presence of fluorocarbons in nature and its great stability encourage science community to found new methods to break the C-F bond of this compounds, because it could be used as a starting reactant in organic synthesis. The stability of aryl fluorides is given because its C-F bond is the strongest single bond in the nature. That is its principal characteristic and the reason of it lack of reactivity. For this reason, it is challenging for scientists found the manner for C-F cleavage. As the same wise, C-O becomes an alternative of C-F to avoid the fluoride waste. This Thesis is about the computational study of the C-F and C-O cleavage through the borylation catalysed by nickel catalyst. Concretely, we have studied three borylation of C-F and C-O bonds and we compared it and show what have in common the three reactions.

The complexes CpRu(PPh$ sb3)$(L)SR (Cp=$ eta sp5$-cyclopentadienyl; R=CMe$ sb3,$ CHMe$ sb2,$ 4-$ rm C sb6H sb4Me)$ reacted with NOBF$ sb4$ to give either (CpRu(PPh$ sb3)$(NO)SR) BF$ sb4$ (L=PPh$ sb3)$ or complexes containing disulfide ligands (L=CO). The bisphosphine complexes, CpRu(PPh$ sb3) sb2$SR, reacted with HBF$ sb4$ to give the corresponding thiol complex salts (CpRu(PPh$ sb3) sb2$(HSR)) BF$ sb4$ and with (MeSSME$ rm sb2 rbrack BF sb4$ to give (CpRu(PPh$ sb3) sb2$(SMe$ sb2)$) BF$ sb4$ regardless of the starting thiolates. The complexes CpRu(PPh$ sb3) sb2$SR reacted with the sulfur transfer agent MeSphth (phth=phthalimido) to give CpRu (PPh$ sb3) sb2$(phth) and the dimers ($ mu$-SMe)($ mu$-SR) (CpRu(phth)) $ sb2$ for R=CMe$ sb3$ or CHMe$ sb2,$ while for R=4-$ rm C sb6H sb4Me$ the same reaction gave CpRu(PPh$ sb3)$(phth)(MeSS-4-$ rm C sb6H sb4Me)$ and ($ mu$-SMe)($ mu$-S-4-$ rm C sb6H sb4$Me) (CpRu(S-4-$ rm C sb6H sb4Me) rbrack sb2.$ The complex CpRu(PPh$ sb3) sb2$ SCH$ sb2$CH=CH$ sb2,$ prepared from the reaction of CpRu(PPh$ sb3) sb2$Cl and LiSCH$ sb2$CH=CH$ sb2,$ reacted with CO and CS$ sb2$ to give CpRu(PPh$ sb3)$(CO)SCH$ sb2$CH=CH$ sb2$ and CpRu(PPh$ sb3)$S$ sb2$CSCH$ sb2$CH=CH$ sb2,$ respectively. Refluxing a toluene solution of CpRu(PPh$ sb3) sb2$SCH$ sb2$CH=CH$ sb2$ gave ($ mu sb3$-S)$ sb2( mu$-SCH$ sb2$CH=CH$ sb2$) (CpRu) $ sb3$ in which the C-S bond has been cleaved.
The complexes (PPh$ sb3) sb2$Pt(SR)$ sb2$ (R=H, $ rm CMe sb3, CHMe sb2,$ 4-$ rm C sb6H sb4Me)$ were treated with SO$ sb2$ as models for the Claus process. These reactions produced adducts of formula (PPh$ sb3) sb2$Pt(S(SO$ sb2)$R)$ sb2,$ which have a labile thiolate-bound SO$ sb2$ molecule, for R=CMe$ sb3,$ 4-$ rm C sb6H sb4Me$ and CHMe$ sb2.$ The reaction of cis-(PPh$ sb3) sb2$Pt(SH)$ sb2$ with SO$ sb2$ gave (PPh$ sb3) sb2$Pt(S$ sb3$O) and H$ sb2$O, a reaction which mimics Claus chemistry. The complexes cis-(PPh$ sb3) sb2$Pt(SH)$ sb2,$ (PPh$ sb3) sb2$Pt(S$ sb3$O) and (PPh$ sb3) sb2$Pt(SR)$ sb2$ catalyze the Claus reaction (2H$ sb2$S + SO$ rm sb2 to3/8S sb8+2H sb2O).$
The complexes (PPh$ sb3) sb2$Pt(SR)$ sb2$ reacted with CS$ sb2$ to form the mixed thiolato-thioxanthato complexes (PPh$ sb3)$Pt(SR)(S$ sb2$CSR) wherein CS$ sb2$ had inserted into one of the Pt-S bonds. The complex cis-(PPh$ sb3) sb2$Pt(SH)$ sb2$ reacted with CS$ sb2$ to give the known complex, (PPh$ sb3) sb2$Pt(S$ sb2$CS), which contains a trithiocarbonate group.
The structures of (CpRu(PPh$ sb3)$(NO)SCMe$ rm sb3 rbrack BF sb4, ( mu$-SMe)($ mu$-S-4-$ rm C sb6H sb4Me)$ (CpRu(S-4-$ rm C sb6H sb4Me) rbrack sb2, ( mu sb3$-S)$ sb2( mu$-SCH$ sb2$CH=CH$ sb2)$ (CpRu) $ sb3,$ (PPh$ sb3) sb2$Pt(S$ sb3$O) and (PPh$ sb3)$Pt(S-4-$ rm C sb6H sb4Me)$(S$ sb2$CS-4-$ rm C sb6H sb4Me)$ were determined by x-ray crystallography.

The work in this thesis couples reactions with separations through the use of switchable and tunable solvents. Tunable solvents are mixed solvents which can be easily altered to afford conditions optimal for reaction or separation. Switchable solvents are solvents that can be switched when desired to alter their properties affording conditions suitable for separation. Other studies are of the reaction of CO2 with the amidine base DBU, and an NMR study of solvent-to-solute nuclear Overhauser effects. These examples constitute a marriage of reaction environment with separation environment, significantly, to the benefit of both.

La dissertation suivante se focalise sur de nouvelles transformations organiques, à travers des transferts d’hydrogènes, en utilisant des complexes en tenaille Mn(I) et Ru(II). L’objectif principal est l’étude des complexes Mn(I) et Ru(II) et leur réactivité similaire lors des réactions de transferts d’hydrogènes, comprenant les réactions d’échanges d’hydrogènes et réductions. Le chapitre 1 est une introduction générale sur les réactions de transferts d’hydrogènes reportées dans la littérature pour les complexes Mn(I) et leur réactivité similaire à celle des complexes Ru(II), connus pour leur capacité à réaliser des transferts d’hydrogènes. Le chapitre 2 traite de l’utilisation de MeOH comme une source de carbone C1 pour la synthèse de produits de chimie fine, pharmaceutiques et carburants alternatifs. La beta-méthylation sélective des alcools a été conduite avec succès en utilisant MeOH comme source de carbone C1. Différents complexes de ruthénium ont été investigués pour cette transformation et le complexe en tenaille Ru-MACHO-BH s’est révélé être le meilleur en termes de résultats catalytiques. Des études mécanistiques et calculs DFT ont confirmé la voie par transferts d’hydrogènes « Hydrogen Borrowing Reaction » et la coopération métal-ligand sur le centre métallique ruthénium. Le chapitre 3, lui aussi, concerne la beta-methylation sélective des alcools à l’aide de MeOH comme source de carbone C1. Cependant, dans ce chapitre, les complexes étudiés sont des complexes en tenaille, stables à l’air, à base d’un métal abondant : le manganèse. La réactivité des deux complexes Mn(I) et Ru(II) a été comparée. De nombreux complexes de manganèse en tenaille ont été synthétisés et testés pour la beta-methylation sélective des alcools à l’aide de MeOH. Pour cette réaction, le complexe Mn-MACHO-iPr a montré les meilleurs résultats avec d’excellentes sélectivités et de très bons rendements. Le chapitre 4 démontre la formation de cycloalcanes substitués en utilisant des alcools secondaires ou des cétones ainsi que des diols comme réactifs de départ, avec les complexes Ru-MACHO-BH ou Mn-MACHO-iPr comme pré-catalyseurs. L’analyse de ces réactions a mis en évidence la meilleure réactivité du complexe Mn-MACHO-iPr en comparaison avec le complexe Ru-MACHO-BH. Différents cycloalcanes substitués comme des cyclopentanes, des cyclohexanes et des cycloheptanes ont été synthétisés avec ce complexe de manganèse. Des études mécanistiques ont révélé que la réaction procède via transfert d’hydrogène « Hydrogen Borrowing reaction ». Le chapitre 5 concerne la deutération sélective d’alcools primaires et aliphatiques en utilisant D2O comme source de deutérium et le complexe précédemment établi Mn-MACHO-iPr comme catalyseur. Les analyses ont montré la deutération sélective d’alcools benzyliques en position alpha et la deutération d’alcools aliphatiques en position alpha et béta. Le chapitre 6 concerne l’hydrogénation sélective de carbonates cycliques en méthanol et diols correspondants. Différents complexes de manganèse en tenaille ont été synthétisés pour confirmer l’actitivité envers cette transformation. Le complexe stable à l’air Mn-MACHO-iPr a montré la meilleure activité catalytique avec des TON élevés ainsi qu’une très bonne sélectivité concernant la formation de méthanol et diols. Le chapitre 7 traite de la préparation de méthoxy-boranes and boronate-diols via réduction sélective de carbonates organiques cycliques et linéaires, ainsi que du CO2, en utilisant le pinacolborane comme agent réducteur. Un nouveau complexe de manganèse en tenaille synthétisé a été exploré et a révélé une grande efficacité et sélectivité pour cette transformation
The present dissertation focuses on new organic transformations enabled by hydrogen transfer reactions using Mn(I) and Ru(II) pincer complexes. The primary focus deals with the study of Mn(I) and Ru(II) complexes and their similar reactivity in hydrogen transfer reactions which includes hydrogen borrowing and reduction reactions.Chapter 1 is a general introduction of hydrogen-transfer reactions reported for Mn(I) complexes and their similar reactivity with the Ru(II) complexes that are well-established for the hydrogen-transfer reactions.Chapter 2 focuses on the utilization of MeOH as a C1 source for the synthesis of fine chemicals, pharmaceuticals and alternative fuels. The selective beta-methylation of alcohols was achieved using methanol as a C1 source. Various ruthenium complexes were investigated for this transformation and a Ru-MACHO-BH pincer complex revealed the best catalytic results. Mechanistic studies and DFT calculations confirmed that the reaction proceeds via “Hydrogen borrowing pathways” and involved metal-ligand cooperation on the ruthenium metal center.Chapter 3 also deals with the selective beta-methylation of alcohols using methanol as a C1 source. However, in this chapter, earth-abundant and air-stable manganese pincer complexes were investigated. The reactivity of Mn(I) pincer complexes with Ru(II) pincer complexes was compared. Numerous manganese pincer complexes were synthesized and checked for this process where the Mn-MACHO-iPr complex demonstrates the optimum results with high selectivity and high yield to the corresponding desired product. Chapter 4 demonstrates the formation of substituted cycloalkanes using secondary alcohols or ketones and diols as initial substrates employing Mn-MACHO-iPr complex as pre-catalyst. The reaction studies showed that the Mn-MACHO-iPr complex revealed better reactivity in comparison to the Ru-MACHO-BH complex. Various substituted cycloalkane rings such as substituted cyclopentane, cyclohexane, and cycloheptane rings were synthesized employing the Mn-MACHO-iPr complex. Mechanistic studies revealed that the reaction proceeds via “hydrogen borrowing pathways”.Chapter 5 addresses the selective deuteration of primary and aliphatic alcohols using D2O as a deuterium source. The already established Mn-MACHO-iPr complex was investigated for this transformation which showed selective deuterations of benzylic alcohols at the alpha positions and alpha and beta deuteration for aliphatic alcohols.Chapter 6 deals with the selective hydrogenation of cyclic carbonates to the analogous methanol and diols. Several manganese pincer complexes were synthesized to confirm the activity towards this transformation. Air-stable Mn-MACHO-iPr pincer complex showed the best catalytic activity with high turnover numbers and selective preparation to the corresponding methanol and diols.Chapter 7 discusses the preparation of methoxy-borane and boronate-diols via selective reduction of cyclic and linear carbonates and CO2 using pinacolborane as a reducing agent. A newly synthesized manganese pincer complex was explored for this process which revealed the high efficiency and selectivity towards this transformation

Cette thèse présente des travaux de méthodologie de synthèse et des études mécanistiques. Une approche complémentaire est utilisée, avec des résultats expérimentaux et des résultats théoriques issus de calculs DFT. Trois réactions ont été étudiées. La première réaction est l’alpha-arylation de cétones énolisables en l’absence de métal de transition. Elle se déroule en présence de DMF et de tBuOK. L’étude mécanistique met en évidence la formation d’une espèce riche en électrons par déprotonation du solvant. La deuxième réaction étudiée est la N-arylation de pyrazoles via la formation d’aryldiazoniums in situ. Cette réaction est catalysée au cuivre. Une évaluation de la méthode DFT la plus adaptée est présentée. Un double cycle catalytique est proposé, faisant intervenir le complexe de cuivre et l’acide acétique. La dernière réaction étudiée est la formation stéréoselective d’alkényl thioethers fluorés trisubstitués par catalyse au cuivre. La méthodologie de synthèse est présentée, suivie d’une étude mécanistique. Celle-ci révèle un mécanisme radicalaire qui peut être généralisé à d’autres substrats
In this thesis, synthetic methodology development and mechanistic studies are presented. A complementary approach, using both experiments and theoretical outcomes from DFT, is used. Three reactions were studied. The first reaction is the transition-metal free alpha-arylation of enolizable ketones. It proceeds using DMF and tBuOK. The mechanistic study reveals the formation of an electron-rich species by deprotonation of the solvent. The second reaction studied is the copper-catalyzed N-arylation of pyrazoles with arenediazonium salts generated in situ. A benchmark is performed to evaluate the best DFT methodology. A double catalytic cycle is proposed, involving copper and acetic acid. The last reaction studied is the copper-catalyzed stereoselective access to trisubstituted fluorinated alkenyl thioethers. The development of the methodology is presented. Then a mechanistic study reveals a radical mechanism that can be generalized to other substrates

La catàlisi homogènia d'or(I) és una eina per a la construcció de complexitat molecular mitjançant l'activació selectiva d'enllaços múltiples C-C. El nostre grup ha desenvolupat una sèrie de reaccions d'alquins amb alquens catalitzades per or(I) tant en forma intramolecular com intermolecular. Aquestes reaccions s’inicien amb l'atac nucleofílic del doble enllaç a l'alquí per formar un intermedi tipus ciclopropil carbé d'or(I) que evoluciona per donar diferents productes. En aquesta tesi doctoral es descriu una sèrie de noves reaccions intermoleculars de alquens amb alquins substituïts amb heteroàtoms catalitzades per or(I). A més, es presenten els estudis mecanístics corresponents, realitzats mitjançant experiments i càlculs DFT. En les reaccions entre bromolaquins i alquens catalitzades per or(I), inicialment es genera un 1-brom ciclopropil carbé d'or(I) que evoluciona a través d'un catió bromoni ciclic per formar un vinilidè d'or(I) o en un catió vinilidilareni estabilitzat per or. Els càlculs DFT demostren que aquests dos intermedis són confòrmers de la mateixa espècie però tenen diferent reactivitat. D'una banda, el vinilidè d'or(I) pot participar en reaciones d'activació C-H o de hidroarilació, mentre que el catió vinilidilareni participa en transposicions 1,2 de l'areni per a formar un triple enllaç. A més, els alquinil èters terminals participen en cicloaddicions [2 + 2] amb alquens per formar ciclobutens que poden convertir-se fàcilment en les corresponents ciclobutanones.
La catálisis homogénea de oro(I) es una poderosa herramienta para la construcción de complejidad molecular en condiciones suaves mediante la activación selectiva de enlaces múltiples C-C. Nuestro grupo ha desarrollado una serie de reacciones de alquinos con alquenos catalizadas por oro(I), tanto de forma intramolecular como intermolecular. Estas reacciones comienzan con el ataque nucleofílico del doble enlace al alquino para formar un intermedio tipo ciclopropil carbeno de oro(I), que evoluciona para dar lugar a diferentes productos. En esta Tesis Doctoral se describen una serie de nuevas reacciones intermoleculares entre alquenos y alquinos sustituidos con heteroátomos catalizadas por oro(I). Además, se presentan los estudios mecanísticos correspondientes, realizados mediante experimentos y cálculos DFT. En las reacciones entre bromoalquinos y alquenos catalizadas por oro(I), inicialmente se genera un 1-bromo ciclopropil carbeno de oro(I) que evoluciona a través de un catión bromonio cíclico para formar un vinilideno de oro(I) o un catión vinilidilarenio estabilizado por oro. Los cálculos DFT demuestran que estos dos intermedios son confórmeros de la misma especie pero tienen diferente reactividad. Los vinilidenos de oro(I) pueden participar en reacciones de activacion C-H o de hidroarilación, mientras que los cationes vinilidilarenio participan en transposiciones 1,2 del areno para formar enlaces triples.
Homogeneous gold(I) catalysis is a powerful tool for the construction of molecular complexity under mild conditions by mean of the selective activation of C-C multiple bonds. Our group developed a series of gold(I)-catalyzed reactions of alkynes with alkenes both in intramolecular and intermolecular settings. These reactions start with the nucleophilic attack of the double bond on the alkyne to form a cyclopropyl gold(I) carbene intermediate that than rearranges into a variety of products. In this Doctoral Thesis we present a series of new gold(I)-catalyzed intermolecular reactions of heteroatom-substituted alkynes with alkenes and the mechanistic investigation we performed by means of experimental work and DFT calculations. In the gold(I) catalyzed reactions of bromoalkynes with alkenes, the 1-bromo-cyclopropyl gold(I) carbene initially formed rearranges into gold(I) vinylidenes and vinylidenephenonium gold(I) cations passing through a cyclic bromonium intermediate. DFT calculations demonstrated that these two reactive intermediates are conformers of the same species but have different reactivity. On one side gold(I)-vinylidenes can undergo hydroarylation or C-H insertion, while vinylidenephenonium gold(I) cations easily undergo 1,2-aryl shift forming a triple bond. Moreover, we found that terminal alkynyl ethers are undergoing efficiently [2+2] cycloaddition with alkenes to form cyclobutene derivatives that can be easily transformed into the corresponding cyclobutanones.

Throughout this dissertation, the versatility of metal-catalyzed cycloaddition reactions for synthesizing structurally diverse bicyclic systems has been demonstrated. Nickel-catalyzed intramolecular [4+4]-cycloadditions have led to cis-eight-membered fused [6.3.0] and trans- or cis- eight-membered fused [6.4.0] bicyclic systems. These intramolecular [4+4]-cycloadditions proceeded efficiently on a set of bis-dienes linked by a three- or four-atom chain to afford cis- or trans-configured bicyclic systems, with one cyclic motif being an eight-membered ring. Computational studies on the stereo-determining step of the reaction have helped rationalize the stereochemical outcome of the reaction. The mechanistic insights gained within the present work for nickel-catalyzed intramolecular [4+4]-cycloadditions contributed to developing an enantioselective version of this transformation with a thorough screening of enantiopure phosphorus- and nitrogen-containing ligands. Research activities within the present dissertation have also demonstrated the versatility and efficacy of XBPhos-Rh combined with silver BArF as catalysts for intramolecular [4+2] cycloadditions of dienynes. This cycloaddition reaction proceeded efficiently on a set of structurally diverse dienynes to afford six-membered carbocycles fused to a five-membered ring. The products were isolated as 1,4-unconjugated cyclohexenes, without aromatization taking place. A tentative rationalization of the reaction pathway involving a Rh/Ag cooperative mechanism has also been suggested.
Al llarg d’aquesta tesi doctoral, s’ha demostrat la versatilitat de les reaccions de cicloaddició catalitzades per metalls de transició amb l’objectiu de sintetitzar sistemes bicíclics estructuralment diversos. Les cicloaddicions intramoleculars [4+4] catalitzades per níquel han conduït a productes bicíclics de tipus [6.3.0] fusionats en cis i de tipus [6.4.0] fusionats en trans o cis. Aquestes cicloaddicions intramoleculars han funcionat en un conjunt de bisdiens units per una cadena de tres o quatre àtoms i han conduït a sistemes bicíclics fusionats en cis o en trans, on un dels anells és de vuit baules. Els estudis computacionals sobre l’etapa estereodeterminant de la reacció han ajudat a racionalitzar l’estereoquímica dels productes obtinguts. Els coneixements mecanístics obtinguts en el present treball per a les cicloaddicions intramoleculars [4+4] catalitzades amb níquel han contribuït al desenvolupament d’una versió enantioselectiva d’aquesta transformació mitjançant un ampli cribatge de lligands enantiopurs basats en fòsfor i nitrogen. Les activitats de recerca dins de la present tesis també han demostrat la versatilitat i eficàcia del complex XBPhos-Rh combinat amb AgBArF com catalitzadors de cicloaddicions intramoleculars [4+2] de dienins. Aquesta reacció de cicloaddició va funcionar de manera eficient en un conjunt de dienins estructuralment diversos per a generar carbocicles de sis membres fusionats a un anell de cinc membres. Els productes es van aïllar com els derivats 1,4-ciclohexènics no conjugats, sense que és produís l’aromatització de l’anell. També s'ha suggerit una racionalització mecanística provisional que implica un mecanisme cooperatiu con rodi i plata.
A lo largo de esta tesis doctoral, se ha demostrado la versatilidad de las reacciones de cicloadición catalizadas por metales de transición para sintetizar sistemas bicíclicos estructuralmente diversos. Las reacciones de cicloadición [4+4] intramoleculares catalizadas por níquel han dado lugar a sistemas bicíclicos de tipo [6.3.0] fusionados en cis y de tipo [6.4.0] fusionados en trans o cis. Estas cicloadiciones [4+4] intramoleculares se aplicaron de forma eficiente a un conjunto de bisdienos unidos por una cadena de tres o cuatro átomos para dar lugar a sistemas bicíclicos fusionados en cis o trans, en los que uno de los anillos era de ocho miembros. Los estudios computacionales sobre el paso estereodeterminante de la reacción han ayudado a racionalizar la estereoquímica de los productos de la reacción. Los conocimientos mecanísticos adquiridos en el presente trabajo sobre las cicloadiciones [4+4] intramoleculares catalizadas por níquel han contribuido a desarrollar una versión enantioselectiva de esta transformación con un cribado exhaustivo de ligandos enantiopuros basados en fósforo y nitrógeno. Las actividades de investigación de la presente tesis también han demostrado la versatilidad y eficacia del complejo XBPhos-Rh combinado con AgBArF como catalizadores para las cicloadiciones [4+2] intramoleculares de dieninos. Esta reacción de cicloadición se aplicó de manera eficiente a un conjunto de dieninos estructuralmente diversos para obtener ciclos carbonados de seis miembros fusionados a un anillo de cinco miembros. Los productos se aislaron como ciclohexenos 1,4-no conjugados, sin que tuviera lugar la aromatización. También se ha sugerido una racionalización mecanística provisional que implica un mecanismo cooperativo con rodio y plata.

This work focuses on understanding the heterogeneous/homogeneous nature of the catalytic species for a variety of immobilized metal precatalysts used for C-C coupling reactions. These precatalysts include: (i) tethered organometallic palladium pincer complexes, (ii) an encapsulated small molecule palladium complex in a polymer matrix, (iii) mercapto-modified mesoporous silica metalated with palladium acetate, and (iv) amino-functionalized mesoporous silicas metalated with Ni(II). As part of this investigation, the use of metal scavengers as selective poisons of homogeneous catalysis is introduced and investigated as a test for distinguishing heterogeneous from homogeneous catalysis. The premise of this test is that insoluble materials functionalized with metal binding sites can be used to selectively remove soluble metal, but will not interfere with catalysis from immobilized metal. In this way the test can definitely distinguish between surface and solution catalysis of immobilized metal precatalysts. This work investigates three different C-C coupling reactions catalyzed by the immobilized metal precatalysts mentioned above. These reactions include the Heck, Suzuki, and Kumada reactions. In all cases it is found that catalysis is solely from leached metal. Three different metal scavenging materials are presented as selective poisons that can be used to determine solution vs. surface catalysis. These selective poisons include poly(vinylpyridine), QuadrapureTM TU, and thiol-functionalized mesoporous silica. The results are contrasted against the current understanding of this field of research and subtleties of tests for distinguishing homogeneous from heterogeneous catalysis are presented and discussed.

A numerical model was developed to examine the behaviour of a vertical laminar flow tubular reactor subject to varying physical properties. Analysis of the results of the model using factorial design techniques indicated that the characteristics of the reactor were closely tied to the heat transfer occurring in the reactor. Three regimes of heat transfer behaviour were identified. These three regimes were instrumental in the effect that varying physical properties had upon reactor performance. In the high heat transfer regime it was found that varying properties were only important when there were appreciable changes in the thermal conductivity and density due to changes in composition. The medium heat transfer regime gave similar results; however, under some conditions changes in heat capacity were found to be significant. In the low heat transfer regime physical property variations had the largest effect. Under these conditions temperature dependent properties were capable of affecting reactor performance when large temperature rises occurred. Concentration dependence was also significant. With respect to concentration dependence of the physical properties, density and heat capacity variations were found to be the most significant in this regime. An experimental program was carried out to verify the more obvious effects determined in the theoretical program. Although the experimental results could not completely be modelled through the developed numerical model, some of the major findings of the numerical study were verified. In the experimental investigation the reaction was carried out in an adiabatic reactor. Some of the differences between theoretical and experimental conversions were directly attributable to the sensitivity of the system to the dimensionless heat of reaction and to free convection. To a smaller extent the effect of a varying heat capacity was observed. The correspondence between numerical and experimental results could be improved if the following modifications were made: (1) Modify the numerical model to allow for the possibility of negative or stagnant flows. (2) In conjunction with the above recommendation the range of values for the buoyancy term that are solvable by the numerical model should be increased. Convergence difficulties were encountered for larger values of $\beta\sb{U}$. These were quite likely due to the manner in which the system pressure was solved. A different formulation of the momentum equation may be necessary. (3) Investigate a reaction in which all of the pertinent information regarding the kinetics and physical property data are readily available. Some of the error between the numerical and experimental results could be attributed to the contradictory literature on the hydrolysis of acetic anhydride. The experimental results also indicated that the heat of reaction, heat capacity and density should be as accurate as possible.

Neste trabalho, várias reações de Heck foram investigadas utilizando principalmente métodos baseados na Teoria do Funcional de Densidade (DFT). Na primeira parte foi proposto um novo ciclo catalítico de Heck, com etapas aniônicas e neutras combinadas desencadeado por um complexo de paládio (Pd) suportado por um ligante carbeno N-heterocíclico (NHC) inédito. Posteriormente, a influência estérica do ligante NHC foi investigada na seletividade da reação de Heck inicialmente estudada. Para o NHC pouco volumoso, a componente eletrônica era majoritária comparada às contribuições de caráter não-covalente. Entretanto, quando o NHC com maior impedimento estérico foi analisado, somente alguns funcionais de densidade (TPSS-D3, ωB97x-D, BP86-D3, e M06-L), juntamente com o método de função de onda DLPNO-MP2, foram capazes de predizer a tendência de seletividade experimental. Por fim, a natureza do metal foi analisada por meio de uma comparação entre catalisadores NHC de níquel (Ni) e Pd nas reações de Heck. Os resultados teóricos forneceram indícios mecanísticos para o entendimento da menor atividade catalítica usualmente encontrada nos processos envolvendo complexos NHC de Ni e da necessidade experimental da formação de complexos de Ni catiônicos para atingir uma maior eficiência catalítica nessas reações. Na segunda parte deste estudo, dois exemplos marcantes da literatura sobre as reações de Heck-Matsuda enantiosseletivas foram teoricamente investigadas. Os cálculos DFT mostraram a influência crucial do substrato (olefina) na seletividade destas reações. Em um dos casos a seletividade da reação foi aprimorada através dos dados mecanísticos fornecidos pelos cálculos DFT.
In this work, several examples of Heck reactions were investigated using mostly Density Functional Theory (DFT) methods. At the first part, a new Heck catalytic cycle was proposed with combined anionic and neutral steps initiated by a newly N-heterocyclic carbene (NHC) based palladium (Pd) complex. Posteriorly, the influence of steric demanding of NHC ligand was investigated on selectivity of Heck reaction initially studied. In the case of small NHC ligand, the electronic component is more important than the noncovalent contributions. However, when the crowded NHC ligands were studied only selected density functionals (TPSS-D3, ωB97x-D, BP86-D3, e M06-L), and the wavefunction based method DLPNO-MP2, were capable to predict the experimental selectivity trends reported. Finally, the metal nature was analyzed by a comparison of the nickel (Ni) and Pd catalyzed Heck reactions. The theoretical results provided mechanistic insights that help to understand the low catalytic activity usually reported when Ni catalysts were used and the experimental requirement of cationic intermediates to achieve some efficiency for NHC-Ni-catalyzed Heck coupling. At second part, two representative examples from literature about the enantioselective Heck-Matsuda reactions were theoretically investigated. DFT calculations shown the crucial influence of substrate (olefin) on the selectivity of these reactions. One of cases studied, the selectivity of reaction was improved by the DFT results

Los compuestos organoborados son considerados de gran interés en síntesis orgánica debido a que el enlace C-B puede ser transformado en una amplia variedad de grupos funcionales. La adicción catalítica de H-B o B-B a enlaces C-C insaturados se considera uno de los procesos catalíticos con mayor control selectivo en la formación de dichos intermedios organoborados.
En el capítulo primero de la presente tesis se muestra la evolución a través de la bibliografía de las tres principales reacciones de adición catalítica de boro a alquenos, como son hidroboración, diboración y -boración.
El segundo capítulo describe por primera vez la hidroboración catalítica asimétrica tanto en version homogénea como heterogeneizada de sistemas alilícos heterofuncionalizados. También describe el primer ejemplo de diboración de fenil alil sulfonas con sistemas catalíticos de Pt modificados con ligandos N-heterocíclicos.
El tercer capítulo muestra la diboración catalítica de alquenos con sistemas catalíticos formados por Cu, Pd e Ir modificados con ligandos NHC. La presencia de una base y la adicción de un exceso de diborano son esenciales para obtener un alto grado de actividad y selectividad.
El cuarto capítulo muestra una efectiva síntesis de boro enolatos quirales usando metales de bajo coste como son Cu y Ni modificados con ligandos NHC quirales y ligandos difosfina quirales respectivamente.
El quinto capítulo describe las reacciones tándem "in situ" tales como adición de boro-acoplamiento cruzado catalizadas por complejos de Pt modificado con ligandos carbenos y Pd modificados con ligandos difosfina.
Organoboron compounds are some of the most useful reagents in organic synthesis. The carbon-boron bond, once formed, can be cleaved in a variety of ways, with or without homologation, leading to a wide range of useful functional groups. The catalytic addition of H-B or B-B across to unsaturated C-C bond is one of the catalytic processes with higher selective control in the C-B bond formation.
In the first Chapter of this thesis shows the evolution through the literature of the three main catalytic reactions of boron addition to alkenes, such as hydroboration, diboration and -boration.
Chapter 2 describes the first attempt at the catalytic asymmetric hydroboration in both homogeneous and heterogenised version of functionalised allylic system. In addition, the first example of the diboration reaction of these mentioned substrates with complexes based on Pt modified with NHC ligands is described.
Chapter 3 discusses catalytic diboration of alkenes based on Cu, Pd and Ir- catalytic system modified with NHC ligands. The presence of a base and the use of an excess of diboron reagent are essential to obtain high degree of activity and selectivity.
Chapter 4 shows the successful synthesis of chiral boron enolates by using inexpensive metals such as copper and nickel modified with chiral NHC ligands and modulated chiral commercially available diphosphines respectively.
In Chapter 5 describes complexes containing transition metals such as platinum and palladium modified with NHC ligands and P,P respectively capable to perform the in situ tandem catalytic boron-addition-Suzuki-Miyaura cross-coupling.

Synthese de l'acetaldehyde par hydrocarbonylation du methanol avec utilisation d'une haute pression et de solvants chelatants, puis synthese selective de l'ethanol a partir de ces resultats. Mise au point d'un systeme catalytique ternaire permettant d'optimiser la reaction d'hydrocarbonylation des alcools superieurs et des esters et de determiner le mecanisme reactionnel

The main contribution of this doctoral thesis has been devoted to the field of synthetic organic chemistry. The Pauson-Khand reaction (PKR) is a metal-catalyzed [2+2+1] cycloaddition between an alkyne, an alkene and a carbon monoxide molecule. In this thesis, we have reported novel synthetic protocols to overcome some limitations. These protocols are based in the use of ethylene glycol as additive, which enhances the selectivities and yields of the corresponding PK adducts in stoichiometric manner, in both intramolecular and intermolecular fashion. Moreover, this positive effect was also observed in catalytic PKR and, furthermore the cobalt catalyst could be recycled by simple liquid-liquid separation when using toluene as reaction solvent. This strategy was then applied to the enantioselective total synthesis of (R)-Sarkomycin, which is an antitumoral agent. Moreover, novel enantio- and regioselective isomerizations have been disclosed, focusing on allylic and heterocyclic compounds, using iridium catalysis or Lewis acids. First, Ir- MaxPHOX catalysts, which were designed by our research group, have been successfully employed in the unprecedented, enantioselective isomerization of allyl amides. On the other hand, commercially available and user-friendly Crabtree’s catalyst has been used for the regioselective isomerization of epoxides and N-sulfonyl aziridines. Finally, we have disclosed that B(C6F5)3, a Lewis acid, promotes the regioselective isomerization of 2,2-disubstituted oxetanes in extremely mild conditions. Moreover, and for all the selective isomerizations of heterocyclic compounds, DFT calculations have been performed to understand the reaction mechanism. Finally, highly enantioselective and efficient catalytic methods to afford chiral β-methyl amines have been reported. Particularly, we have studied the asymmetric hydrogenation of N-protected allyl amines, which are a class of minimally functionalized olefins. For this enantioselective transformation, iridium catalysts bearing chiral phosphine-oxazoline ligands (UbaPHOX and MaxPHOX) have been used. As result, enantioenriched chiral amines were obtained in high enantiomeric excesses. To showcase the applicability of this methodology, we have reported the formal synthesis of Lorcaserin, which is an anorectic, among some other examples of bioactive compounds.
La principal contribución de esta tesis doctoral se ha dedicado al campo de la química orgánica sintética. La reacción de Pauson-Khand (PKR) es una cicloadición catalizada por metales [2 + 2 + 1] entre un alquino, un alqueno y una molécula de monóxido de carbono. En esta tesis, hemos informado sobre nuevos protocolos sintéticos para superar algunas limitaciones. Estos protocolos se basan en el uso de etilenglicol como aditivo, que mejora las selectividades y rendimientos de los aductos PK correspondientes estequiométricamente, tanto intramolecularmente como intermolecularmente. Además, este efecto positivo también se observó en la PKR catalítica y, además, el catalizador de cobalto podría reciclarse mediante simple separación líquido-líquido cuando se usa tolueno como disolvente de reacción. Esta estrategia se aplicó luego a la síntesis enantioselectiva total de (R)-Sarkomicina, que es un agente antitumoral. Además, en esta tesis doctoral se han revelado nuevas isomerizaciones altamente regioselective, centrándose en compuestos alílicos y heterocíclicos, utilizando catálisis de iridio o ácidos de Lewis. Primero, los catalizadores Ir-MaxPHOX, que fueron diseñados por nuestro grupo de investigación, se han utilizado con éxito en la isomerización enantioselectiva sin precedentes de alilamidas. Por otro lado, el catalizador de Crabtree se ha utilizado para la isomerización regioselectiva de epóxidos y N-sulfonil aziridinas. Finalmente, hemos revelado que B(C6F5)3, un ácido de Lewis, promueve la isomerización regioselectiva de oxetanos 2,2-disustituidos en condiciones extremadamente suaves. Además, en todos estos procesos de isomerización de heterociclos se han realizado cálculos de DFT sobre el mecanismo de reacción. Finalmente, se han desvelado nuevos métodos catalíticos altamente enantioselectivos que proporcionan β-metilaminas quirales de forma eficiente. En particular, hemos estudiado la hidrogenación asimétrica de alilaminas N-protegidas, que son una clase de olefinas mínimamente funcionalizadas. Para esta transformación enantioselectiva, se han usado catalizadores de iridio que llevan ligandos quirales de fosfina-oxazolina (UbaPHOX y MaxPHOX). Como resultado, se obtuvieron aminas quirales con excesos enantioméricos elevados. Para mostrar la aplicabilidad de esta metodología, hemos presentado la síntesis formal de Lorcaserin, que es un anoréxico, entre otros ejemplos de compuestos bioactivos.

Commercial fuels are mixtures with large numbers of components. Continuous thermodynamics is a technique for modelling fuel mixtures using a probability density function rather than dealing with each discreet component. The mean and standard deviation of the distribution are then used to model the chemical reactions of the mixture. This thesis develops the necessary theory to apply the technique of continuous thermodynamics to the oxidation reactions of hydrocarbon fuels. The theory is applied to three simplified models of hydrocarbon oxidation: a global one-step reaction, a two-step reaction with CO as the intermediate product, and the four-step reaction of Müller et al. (1992), which contains a high- and a low-temperature branch. These are all greatly simplified models of the complex reaction kinetics of hydrocarbons, and in this thesis they are applied specifically to n-paraffin hydrocarbons in the range from n-heptane to n-hexadecane. The model is tested numerically using a simple constant pressure homogeneous ignition problem using Cantera and compared to simplified and detailed mechanisms for n-heptane. The continuous thermodynamics models are able not only to predict ignition delay times and the development of temperature and species concentrations with time, but also changes in the mixture composition as reaction proceeds as represented by the mean and standard deviation of the distribution function. Continuous thermodynamics is therefore shown to be a useful tool for reactions of multicomponent mixtures, and an alternative to the "surrogate fuel" approach often used at present.

This thesis investigates the fast-reaction limit for a one dimensional reaction-diffusion system describing the penetration of the carbonation reaction in concrete. Three conceptually different scaling regimes of the effective diffusivities of the driving chemical species are explored using matched asymptotics. The limiting models include one-phase and two-phase generalised Stefan moving boundary problems as well as a nonstandard two-scale (micro-macro) moving boundary problem. These sharp interface models are studied to uncover the mechanisms at the free boundary. A power law for the concentration of the chemical species at the interface is derived, as well as the large and small time asymptotic behaviour of the free boundary and the concentration profiles. Numerical results, supporting the analytical results, are presented throughout this thesis, including the application of the method of lines to solve the limiting Stefan problems. To conclude, numerical illustrations of different two-dimensional geometries are included.

The efficient conversion of solar energy into a chemical fuel represents a technological milestone that would engender society with a clean and renewable source of energy orders of magnitude more powerful than our current consumption. By dividing the process into two complementary half reactions each step of the conversion can be assessed and modified independently. Of the potential oxidants, few are better than the currently employed dioxygen gas but the formation of oxygen from reduced species is plagued by high thermodynamic barriers and requires multiple concerted proton and electron transfers. Homogeneous catalysis is an excellent platform from which to study these reactions and iridium complexes in particular have been shown to be highly active and long-lived in contrast to several other water oxidation catalysts. Building on the wealth of knowledge already contained in the literature, this thesis describes the in situ speciation and provides evidence for the homogeneity of a class of iridium complexes capable of water oxidation over an extended period of time. In contrast to initial evidence that a single site was sufficient, spectroscopic and computational investigations support the formation of a dimeric species at the expense of a sacrificial place-holder ligand, Cp*. The dimeric complex then undergoes several sequential proton coupled electron transfer steps to generate at least one iridium(V) species followed by nucleophilic attack of a solvent water to form the difficult O-O bond. An additional consequence of dividing the overall reaction into two complementary half reactions is the choice of oxidant. Investigations also support the non-innocence of the oxidants employed underpinning the importance of reaction conditions. Despite these complications, these catalysts are robust and highly active.

Els compostos organoborats són intermedis de reacció molt valuosos en síntesi orgànica, degut a que l'enllaç carboni-bor pot ser derivatitzat de múltiples maneres. La diboració catalitzada d'alquins i alquens ha estat ampliament estudiada en els darrers quinze anys, essent la diboració catalitzada d'alquins un procés en el que s'han obtingut elevats rendiments i activitats. No obstant això, en la diboració catalitzada d'alquens la presència de la reacció secundaria de b-eliminació de H sempre s'ha presentat com un seriós inconvenient, impedint un bon compromís entre activitat catalítica i quimioselectivitat.
En el primer capítol de la present tesi es recull l'evolució a través de la bibliografia de les reaccions de diboració d'alquens i alquins, els diferents metalls i lligands utilitzats en la reacció catalítica de diboració i els estudis mecanístics que s'han realitzat fins a data d'avui. Tanmateix, s'han posat de manifest les diferents derivatitzacions que s'han dut a terme a partir d'intermitjos organoborats. També es descriu breument la tècnica de les microones. Com a punt final del capítol, s'introdueixen els objectius de la tesi, incloent-hi el desenvolupament de nous sistemes catalítics que millorin l'activitat, quimioselectivitat i enantioselectivitat dels catalitzadors reportats prèviament en la reacció de diboració catalítica, l'estudi del mecanisme de la reacció de diboració d'alquens catalitzada per rodi, i la busqueda de nous mètodes de fluorofuncionalització d'esters vinic(bisboronics).
En el segon capítol es descriu l'activitat, quimioselectivitat i enantioselectivitat de diferents precursors catalítics en la diboració catalitzada d'alquens i alquins. En el primer apartat es porta a terme un estudi en profunditat de la diboració d'alquens catalitzada per compostos de Rh(I), observant-se que en aquest cas els efectes estèrics en el diborà tenen un efecte dramàtic en la quimioselectivitat de la reacció. També s'observa que el lligand que ofereix una major quimioselectivitat es el DPPM (bis(difenilfosfino)metà), mostrant una influència del bite angle del lligand, mentre que el lligand QUINAP (1-(2-difenilfosfino-1-naftil)isoquinolina) és el que ofereix una major enantioselectivitat. En els següents apartats es descriu la utilització de diferents complexos d’or, argent, coure i platí modificats amb lligands carbens, els quals augmenten la quimioselectivitat de la reacció, reduïnt la producció de subproductes de b-eliminació de H. Malgrat que s’han utilitzat diferents carbens quirals, només en un cas s’ha aconseguit induir asimetria, utilitzant un complex de Cu(I) modificat amb un lligand carbé quiral, però comprometent la quimioselectivitat. També es descriu l’aplicació de carbens de platí i coure a la diboració catalitzada d’alquins, obtenint-se bons resultats d’activitat i quimioselectivitat. La utilització d’unes noves condicions de reacció, en les que es requereix un excés de diborà (2 eq.) i l’addició d’una base (NaOAc), fa que precursors catalítics en principi inactius, com complexos d’Au(I) modificats amb lligands difosfina tipus BINAP (2,2'-bis(difenilfosfino)-1,1'-binaftil), donin bons resultats d’activitat i quimioselectivitat, encara que malauradament no indueixen asimetria. Per últim, es descriu l’aplicació de les tècniques de microones com a mitjà d’acceleració en la diboració d’alquins catalitzada per Pt(0), disminuint-se espectacularment els temps de reacció. En el tercer capítol de la tesi es porta a terme un estudi mecanístic de la reacció de diboració d’alquens catalitzada per Rh(I)-QUINAP. En primer lloc es porta a terme un estudi de RMN (Ressonància Magnètica Nuclear) per a detectar les possibles espècies metàl·liques implicades. A partir d’aquí, es realitza un estudi computacional DFT (Density Functional Theory) del mecanisme de reacció, observant-se que després de l’addició oxidant es produeix la inserció de l’alqué en un enllaç Rh-B, seguida d’un reordenament per a ocupar la posició vacant creada, finalitzant amb la eliminació reductora del producte, essent el camí més favorable aquell en el qual l’alquè queda coordinat trans al nitrogen del lligand QUINAP. L’estudi de la reacció secundària de b-eliminació de H demostra que la utilització de BINAP com a lligand l’afavoreix, en comparació amb la utilització del lligand QUINAP.
En el quart capítol es descriu la flurofuncionalització d’ésters vinil (bisborònics), la qual dóna lloc a la formació de cetones a,a-difluorades a través d’un procés de fluoració electròfila. Primer de tot, es fa una petita introducció als processos de fluoració electròfila, amb especial interès en la fluoració electròfila de compostos organosilats, els quals estan força relacionats amb els compostos organoborats. La reacció es duu a terme a partir dels alquins, a través d’un procés tandem de diboració catalítica/fluoració electròfila. Només els esters vinil(bisborònics) derivats del bis(pinacolato)diborà són susceptibles d’ésser derivatitzats d’aquesta manera. Els alquins interns són més actius que els alquins terminals. També es descriu la síntesi d’a,a-difluoroimines directament a partir d’alquins mitjançant un procés tandem de diboració catalítica/fluoració electròfila/iminació, l’eficiència del qual depen de les propietats electròniques del sustrat.
Per últim, en el capítol 5 es descriu la fluoració electròfila asimètrica d’a- nitroésters, la qual es porta a terme mitjançant la utilització d’auxiliars quirals derivats d’alcaloids de cincona, obtenint-se excessos enantiomèrics de fins a un 40%.
Organoboron compounds are very useful intermediates in organicsynthesis, because the carbon-boron bond can be cleaved in a variety of ways leading to the formation of useful functional groups. The catalyzed diboration ofalkenes and alkynes has been widely studied in the last 15 years, obtaining high yields and activities in the alkyne catalyzed diboration reaction. However, when alkenes are used as substrates in the catalyzed diboration reaction, the problem of b-hydride elimination could arise, preventing a good agreement between catalytic activity and chemoselectivity.
In the first chapter of this thesys an overview of the precedents of the diboration reactions of alkenes and alkynes is presented, including the different metals and ligands used in this reactions and the mechanistic studies published to date. Moreover, there has been collected the different derivatizations of organoboron intermediates carried out. The microwave technique is also described briefly. Finally, the scope of this thesys is explained, including the development of new catalytic systems which improve the activity, chemoselectivity and enantioselectivity of the catalytic systems previously reported, the study of the mechanism of the rhodium catalyzed alkene diboration reaction, and the search of new routes for the fluorofunctionalization of organoboron compounds.
In the second chapter, the activity, chemoselectivity and enantioselectivity of different catalytic precursors in the alkene and alkyne catalytic diboration reaction is described. In the first part, a deep study on the rhodium catalyzed alkene diboration reaction is carried out, finding in this case that the steric effects on the diborating reagent have a dramatic effect on the chemoselectivity of the reaction. It is also observed that the DPPM (bis(diphenylphosphino)methane) is the ligand which provide a better chemoselectivity, showing an important bite angle influence on the ligand, while QUINAP (1-(2-diphenilphosphino-1-naphthyl)isoquinoline) is the ligand which offers a higher enantioselectivity. In the next parts it is described the utilization of different gold, silver, copper and platinum complexes as catalyst precursors, which improve the chemoselectivity of the reaction, reducing the b-hydride elimination side reaction. Despite several chiral carbene modified complexes have been used, only in one case some enantioselectivity was induced, using a carbene modified copper complex, but reducing chemoselectivity. It is also described the application of arbene modified copper and platinum complexes as catalyst precursors in the alkyne diboration reaction, obtaining good results in activity and chemoselectivity. The utilization of new reaction conditions, in which an excess of the diborating reagent (2 eq.) and the addition of a base (NaOAc) is required, improve the activity of catalytic systems like BINAP 2,2’-bis(difenilfosfino)-1,1’-binaphthyl) modified gold complexes, whose activity was very low under the typical conditions; unfortunately, no enantioselectivity was obtained in this case. Finally, it is described the application of microwave techniques to the platinum catalyzed alkyne diboration reaction, in order to reduce the reaction times.In the third chapter, an in-depth study of the mechanism of the Rh(I)-catalyzed alkene diboration reaction is described. First of all, an NMR (Nuclear Magnetic Ressonance) study was carried out in order to identify plausible intermediates. Next, a DFT (Density Functional Theory) study of the reaction mechanism was carried out, finding that after the oxidative addition of the diborane, an insertion of the alkene into a Rh-B bond is produced, followed by an internal rearrangement in order to ocupy the vacant position created, and,finally, reductive elimination of the product is produced, being the most favourable path that in which the alkene is placed trans to the nitrogen of the QUINAP ligand. The study of the b-hydride elimination side reaction shows that the utilization of BINAP as ligand favours it, with respect to the utilization of QUINAP.
In the fourth chapter, the fluorofunctionalization of cis-1,2-bis(boryl)alkenes is described, leading to the formation of a,a-difluorinated ketones through an eletrophilic fluorination process. First of all, a little introduction to the electrophilic fluorination processes is made, with special interest to the electrophilic fluorination of organosilanes, which are quite similar to the organoboron compounds. The reaction is carried out starting from alkynes, through a tandem catalytic diboration/electrophilic fluorination process process. Only the cis-1,2-bis(boryl)alkenes derived from bis(pinacolato)diboron are susceptible to the fluorination process. Internal alkynes are more reactive than terminal ones. It is also described the synthesis of a,a-difluoroimines directly from alkynes through a tandem catalytic diboration/electrophilic fluorination/imination process, the efficiency of which depends on the electronic properties of the substrate.
Finally, in the fifth chapter, the asymmetric electrophilic fluorination of a-nitro esters is described. This process was carried out using cinchona derivatives chiral auxiliaries, obtaining enantiomeric excesses up to 40%.

Aquesta Tesis Doctoral s'ha centrat en l'estudi computacional mitjançant metodologia DFT (Teoria del funcional de la densitat) de reaccions redox catalitzades en fase homogènia. La primera part recau en l'estudi computacional de dos cicles catalítics d'acoblament oxidatiu. Aquest estudi ha aconseguit desxifrar una de les claus d'aquest tipus de reaccions, l'efecte de l'oxidant extern. Demostrem que en totes dues reaccions, diferents metalls de transició poden col•laborar per a donar una reacció més eficient i selectiva. A més a més, descobrim els factors claus per a la regioselectivitat de les dues reaccions estudiades. La segona reacció va ser estudiada en col•laboració amb el grup experimental del Prof. Frederic Patureau (University of Kaiserslautern). La segona part de la tesis es centra en canvi en l'estudi teòric de la reacció d'oxidació de l'aigua catalitzada per complexes de la primera serie de transició. S'ha desenvolupat una nova família de catalitzadors mononuclears de coure en col•laboració amb el grup del Prof. Antoni Llobet (ICIQ). S'ha descobert un nou mecanisme de formació de l'enllaç oxígen-oxígen que consisteix en l'atac nucleòfil de l'aigua mitjançant la transferència d'un electró (SET-WNA). Un cop descobert aquest mecanisme, es va veure que també operava sobre altres catalitzadors de coure i ruteni, redefinint així el context mecanístic d'aquesta reacció en catàlisis homogènia. Aquesta tesis, per tant, proporciona una profunda base mecanística sobre importants reaccions redox mitjançant la química computacional a través dels mètodes DFT.
Esta Tesis Doctoral se ha centrado en el estudio computacional mediante metodología DFT (Teoría del funcional de la densidad) de reacciones redox catalizadas en fase homogénea. La primera parte versa sobre el estudio computacional de dos ciclos catalíticos de acoplamiento oxidativo. Este estudio dio con una de las claves en este tipo de reacciones, el efecto del oxidante externo. Demostramos en ambas reacciones como diferentes metales de transición podían colaborar para dar una reacción más eficiente y selectiva. Además descubrimos las claves para la regioselectividad en ambas reacciones. La segunda reacción fue estudiada en colaboración con el grupo experimental del profesor Frederic Patureau (University of Kaiserslautern). Por otro lado, la segunda parte de esta tesis se centra en el estudio teórico de la reacción de oxidación de agua catalizada por complejos de la primera serie de transición. Desarrollamos una nueva familia de catalizadores mononucleares de cobre con la colaboración experimental del grupo del profesor Antoni Llobet (ICIQ), descubriendo un nuevo mecanismo en la formación de enlace oxígeno-oxígeno, el ataque nucleófilo del agua mediante la transferencia de un electrón (SET-WNA). Tras esto extendimos este mecanismo a otros sistemas de cobre y de rutenio, redefiniendo el contexto mecanístico para esta reacción en catálisis homogénea. Esta tesis, por tanto, proporciona una profunda base mecanística sobre el estudio de importantes reacciones redox mediante química computacional a través de los métodos DFT.
This Doctoral Thesis is focused on the computational study by DFT methodology (Density Functional Theory) of homogeneous redox catalized reactions. The first part describes successfully the mechanism of two different catalytic cycles of oxidative coupling reactions. This study found out the explanation about one of the challenging questions on the field, the key role of the external oxidant. We demonstrated the cooperation between different transition metals is essential to catalyze the reaction efficiently and with good selectivities. Additionally, we explained also the regioselectivity of both reactions, in very good agreement with the experimental results. The second reaction was studied in collaboration with the experimental group of professor Frederic Patureau (University of Kaiserslautern). On the other hand, the second part of the thesis is focused on the theoretical study of water oxidation reaction catalyzed by first-row transition metal complexes. Firstly, we developed a new family of mononuclear copper complexes in collaboration with the experimental group of professor Antoni Llobet (ICIQ), discovering a new mechanism for the oxygen-oxygen bond formation step, the water nucleophilic attack. single electron transfer (SET-WNA). From this point, we extended the new mechanism to other catalytic systems based on copper and ruthenium, redefining the mechanistic scenario for the homogeneous catalytic version of this reaction. Therefore, this thesis provides a deep theoretical knowledge abour the homogeneous redox catalysis mechanisms by DFT calculations.

Energy usage is continually on the rise and significant efforts are being extended to provide more renewable energy. One area of exploration is the development of fuel cells, which includes biofuel cells that can extract energy from carbohydrates obtained from biomass. Recently, viologen catalysts have been shown to enhance reaction rates of energy extraction and improve carbohydrate conversion efficiencies. However, characterizing the effects of process parameters such as pH, reactant concentrations, and carbohydrate exposure time to buffer solutions with a rigorous model is lacking. This thesis characterizes the homogeneous reaction between carbohydrates and a methyl viologen catalyst to provide insights on ways to enhance the reaction rates to produce more energy. Specifically, the rate of formation of reduced methyl viologen (MV+) in the presence of carbohydrates was measured based on changes in the MV2+ concentration, carbohydrate concentration, pH, and carbohydrate exposure time. A rigorous mechanistic model of the reaction rate was developed and showed a first-order dependence on OH- concentration, a zero-order dependence when the MV2+ concentration was >> 0.5 mM, and a 3-fold increase in the reaction rate when glucose was pre-incubated in a pH 12 buffer solution for 100 minutes. The pre-incubation effect had a strong dependence on pH. The mechanistic model agreed well with experimental data. This thesis also addresses the decomposition of viologen catalysts. MV2+ decomposition experiments showed a trend seen previously in literature that the rate of decomposition increases with an increase in MV2+ concentration, OH- concentration, and temperature. The data and mechanistic model suggest second order dependence of both MV2+ and OH- concentrations under conditions in this thesis (MV2+ concentrations of 100-300 mM and OH- concentrations of 0.001 M and 0.01 M). An activation energy was found from MV2+ decomposition to be 145 kJ/mol. MMV+ decomposition was shown to decompose anywhere from 6.2 – 16.1 times slower than MV2+. Therefore, MMV+ decomposes slower and is more stable than MV2+. It was also found that MV2+ is more stable than IPV-Cl and IPV-Br. An analysis was performed to find the recommended operating range for MV2+/glucose biofuel cells under different conditions while ensuring that at least a viable amount of energy could be produced.

Bis(diphenylphosphino)amine (PNP) ligands, prepared from (S)-(-)-1-methylbenzyl amine, (-)-cis-myrtanylamine, (S)-(-)-1,1-napthyl(ethyl)amine (PNP1 1a, PNP2 1b, and PNP3 1c respectively) and their cobalt carbonyl complexes are reported. In the absence of alkynes the PNP ligands chelate to the cobalt rather than bridging the two cobalt centers. Although the PNP ligands are chiral the crystal structures are best solved in centrosymmetric space groups with disorder at the chiral carbon with the exception of (PNP3)Co2(CO)6, 2c, which is solved in a non-centrosymmetric space group. When the PNP ligand chelates to cobalt, as in 2, the compounds show activity for the catalytic Pauson-Khand reaction, whereas when the PNP ligand bridges, as in 3, the reaction precedes stiochiometrically. The use of these chiral ligands has not yet resulted in enantioselective catalytic Pauson-Khand cycloadditions. However, a small 15% e.e. was detected for the stiochiometric Pauson-Khand cycloaddition with 3c as the metal substrate.
Master of Science

Cette thèse est constituée de deux parties indépendantes. La première consiste à former de nouveaux systèmes catalytiques hétérogènes par intercalation d’éthylacétonate de cuivre et de fer dans une argile : la bentonite. Pour cela, celle-ci est purifiée avant d’inclure les deux complexes. Une étude de l’activité de ces deux matériaux a été réalisée avec le diazoacétate d’éthyle afin de former le fumarate et le maléate d’éthyle. Des réactions d’insertion de carbènes ont ensuite été étudiées avec des amines et des alcools en vue de former respectivement des a-oxa et a-aza acétates d’éthyles avec des rendements de l’ordre de 60 à 95%. L’objectif de la seconde partie est d’étudier, en milieu homogène, la réaction de cyclopropanation asymétrique d’alcènes catalysée au cuivre (I) ; les motifs cyclopropaniques étant présents dans de nombreux composés possédant des activités biologiques. Pour ce faire, la synthèse de nouveaux ligands oxazolines et imines issus de l’isosorbide et l’isomannide, deux composés de la biomasse a été réalisée. Complexés au cuivre (I), ces ligands ont été évalués pour la cyclopropanation asymétrique du styrène, de l’ a-méthylstyrène, de l’indène, de l’oct-1-ène en présence de diazoacétate d’éthyle. La cyclopropanation du cyclopentène a de même été réalisée. Divers paramètres ont été examinés afin de déterminer les meilleures conditions réactionnelles. Les résultats les plus significatifs en terme de diastéréosélectivité et d’énantiosélectivité ont été obtenus lors de la cyclopropanation du styrène avec un complexe oxazoline/CuI (diastéréoselection trans/cis : 90/10, ee : 93% pour l’isomère trans). De plus, nous avons montré qu’un système diimine/Cu(CH3CN)4PF6 a donné des stéréosélectivités similaires pour la cyclopropanation du styrène et de l’ a-méthylstyrène, indiquant ainsi que ce système était moins substrat dépendant
This thesis is divided in two independent parts. The first concerns the development of new heterogeneous catalytic systems involving intercalation of ethylacetonate copper and iron complexes in a clay: the bentonite. For this purpose, the bentonite is purified prior to the inclusion of the two complexes. A study of the catalytic activity of these two materials was performed with ethyl diazoacetate to form ethyl fumarate and maleate. Carbene insertion reactions were then studied with amines and alcohols to form respectively a-oxa and a-aza ethyl acetate derivatives in 60 to 95% yields. The aim of the second part is to study, the homogeneous catalytic asymmetric cyclopropanation reaction of alkenes catalyzed by copper (I) complexes; the cyclopropane unit being present in many compounds presenting biological activities. For that purpose, the synthesis of new oxazolines and imines ligands derived from isosorbide and isomannide, two compounds of the biomass was performed. Complexed with copper (I), these ligands were evaluated for the asymmetric cyclopropanation of styrene, of a-methylstyrene, indene, of oct-1-ene in the presence of ethyl diazoacetate. Cyclopropanation of cyclopentene was similarly performed. Various parameters were examined to determine the best reaction conditions. The most significant results in terms of diastereoselectivity and enantioselectivity were obtained in the cyclopropanation of styrene with a complex oxazoline/CuI (diastereoselection trans/cis: 90/10, ee : 93% for the trans isomer). Furthermore, we showed that a catalytic system formed by a diimine and Cu(CH3CN)4PF6 gave similar stereoselectivities for the cyclopropanation of styrene and a-methyl styrene, indicating that the system is less dependent on the nature of the substrate

HCCI engines are a class of engines which use high compression ratio to ignite a charge of air-fuel mixture, essentially eliminating the need for spark plugs. This contrasts with diesel engines (although HCCI can be used for diesel engines) where the fuel is injected near the top dead center of the compression stroke regime. Gasoline HCCI engines are of significance because, it attempts to improve the characteristics of the engine for example the thermal efficiency. High compression ratio comes with higher thermal efficiency, yet the peak temperature remains low enough to have low production rates of harmful oxides of nitrogen and formation of soot. However, there are certain challenges associated with such type of engine, one of which and perhaps the most important of all is how to control the combustion rate. Flow dynamics and chemical-kinetics analysis, is essential to predict combustion timing, duration, and rate. The objective of this study is to analyze a HCCI engine using, simulation analysis models including a three-dimensional CFD simulation model. Simulation analysis is carried out using a generic HCCI engine, initially with simplified chemical kinetics, and then using detailed chemical kinetics and using RANS turbulence CFD model. A sensitivity analysis of the effect of RPM on the combustion time, burn duration, heat release, efficiency and emission concentration are carried out.

This thesis is divided into three main results chapters that reflect the path my research took. In the first results chapter, the first organocatalyst for the carbonyl-ene reaction was discovered and found to give high conversion using 1,3-bis(3,5-bis(trifluoromethyl)phenyl)thiourea. Various carbonyl and alkene precursors were examined in the ene reaction in both catalysed and uncatalysed reactions. It was found that ene reactions using fluoral and ethyl trifluoropyruvate give higher rates of reaction when compared to other carbonyl compounds. A novel enantiopure thiourea was synthesised and the ene reaction was catalysed enantioselectively to 33% e.e. In an attempt to catalyse the reaction to a further extent a new thiourea bonded to a P(=S)R2 group was developed. However, the intramolecular hydrogen bonding of this catalyst was thought to be so strong that this it did not catalyse the reaction. The synthesis of a chiral phosphoric acid was achieved but this was an unsuccessful catalyst in the ene reaction. Two component achiral thiourea and chiral acids were also examined in the ene and Mannich-type reaction. The new easily synthesised thiourea for this reaction has an interesting intermolecular hydrogen bonding coordination in the solid state. Asymmetric fluorination of ketoesters using palladium is a dynamic kinetic resolution. In the 2nd chapter cationic palladium complexes were synthesised and used to determine the optimum parameters for bidentate ligands in this reaction. Four carbon chain phosphines were found to give the highest conversion for this reaction among those ligands tested such as 1,4-bisdiphenylphosphinobutane (bite angle 99º). A new bis-phosphinous amide chiral ligand was developed with a bite angle of 96.7º. The dichloropalladium complex of this phosphine was isolated and structurally characterised. The use of the palladium complex in asymmetric fluorination was attempted however this was found to be unsuccessful. Mechanistic studies reveal that the formation of the desired cationic catalyst did not occur under conditions shown to work well for other palladium phosphine complexes. The ligand was investigated further in hydrogenation reactions. The phosphinous amide was protected as its borane and was used in the rhodium catalysed hydrogenation of alkenes to give high conversion and up to 93% e.e. The borane protected phosphinous amide was also found to catalyse the hydrogenation of acetophenone using copper complexes with up to 84% e.e for the hydrogenation of acetophenone, although conversion was quite low.

Thesis (Ph. D.) -- University of Maryland, College Park, 2008.
Thesis research directed by: Dept. of Chemical and Biomolecular Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Source de carbone la plus abondante du règne végétal et non concurrentielle de la chaîne alimentaire, la cellulose est une alternative aux ressources fossiles crédible pour le développement de nouveaux matériaux polymères. Néanmoins, à ce jour, les nombreux travaux décrits dans la littérature et visant la valorisation et la modification chimique de ce biopolymère fascinant ne répondent pas suffisamment, ou tout au moins que très partiellement, aux critères de durabilité. Pour répondre à ces critères de développement durable, le caractère renouvelable de la cellulose et les concepts de procédés propres et de chimie ‘verte’, doivent être réellement pris en compte. Ceci implique un choix réfléchi des solvants et réactifs utilisés, une maîtrise des procédés de modification chimique et bien évidemment une évaluation de la pertinence des produits formés, pour lesquels les propriétés obtenues doivent être innovantes et supérieures aux matériaux polymères existants. Cette thèse se divise en trois parties principales, à savoir la solubilisation, la régénération et la modification chimique de la cellulose. Tout au long de ce travail, une attention particulière a été portée sur la durabilité de sa transformation chimique pour viser l’élaboration de matériaux cellulosiques processables et aux propriétés innovantes. Dans la première partie de la thèse, un système composé d’un catalyseur organique nucléophile (DBU) et de CO2 a permis la dissolution rapide de la cellulose dans le DMSO. Une étude détaillée visant à optimiser le système DMSO-DBU-CO2 a été réalisée grâce à un suivi par spectroscopie infrarouge in situ. Ainsi, jusqu'à 8 % massique de cellulose ont pu être dissous en 15 minutes à 30 °C sous une faible pression de CO2 (2-5 bars). L’originalité de ce système commutable (fixation-relargage réversible du CO2), par comparaison aux autres solvants classiques de la cellulose, inclut une recyclabilité plus facile par simple dépressurisation du CO2 et une solubilisation rapide et douce, à plus bas coût, en comparaison aux systèmes utilisant les liquides ioniques. La mise en évidence de la création de fonctions carbonate par réaction avec différents composés électrophiles tels les halogénures d’alkyle a permis d’avoir une connaissance approfondie de ce système. L'optimisation réussie d'un système ‘propre’ permettant la dissolution de la cellulose nous a conduit à étudier sa régénération. Dans cet objectif, des aérogels de cellulose ont été préparés par un procédé de solubilisation, coagulation et lyophilisation. Différents paramètres ont été examinés tels la concentration en cellulose, le solvant de coagulation ou encore la nature et concentration en super-base (DBU-CO2), sur les propriétés des aérogels (densité, morphologie, taille des pores). Les résultats obtenus démontrent que des aérogels avec une densité entre 0.05 et 1,2 g/cm3, des porosités entre 92 et 97 % et des tailles de pore entre 1,1 et 4,5 μm ont été obtenus. Enfin, l’analyse des aérogels par microscopie électronique à balayage (SEM), a révélé la formation de réseaux de cellulose interconnectés et macroporeux. La modification chimique de la cellulose pour l’élaboration de matériaux processables aux propriétés innovantes fait l’objet de la troisième partie de la thèse. Cette partie est divisée en deux sous-parties: la dérivatisation de la cellulose par réaction de transestérification d’une part, et par réaction multi-composants, d’autre part. Dans la première sous-partie et gardant à l'esprit les principes de la chimie verte, la nature unique du système commutable DBU-CO2 amenant un changement d’hydrophilie du squelette cellulosique a permis l’utilisation directe de l’huile de tournesol pour la transestérification de la cellulose. [...]
As the most abundant source of carbon in our planet, without any competition with food or feed supplies, cellulose is a viable alternative to replace the widely used and unsustainable fossil-based polymers. However, the majority of researchers working on this fascinating biopolymer fail to incorporate sustainability considerations during cellulose chemical transformation to make materials. The consequence is a shift of the “environmental burden” to other stages of the process cycle. Therefore, to ensure sustainability, both the renewability feature of cellulose as well as sustainability considerations concerning its transformation processes are necessary. This implies to consider the solvent, the reactants, the derivatization process and the wastes produced as well as an evaluation of the suitability of the resultant products, for which relevant properties have to be obtained to compete with existing alternatives. This thesis is therefore divided into three main parts (solubilization, regeneration and derivatization of cellulose), and addresses the various concerns of sustainability during cellulose transformation with an end-goal of making processable materials.In the first part of the thesis, a sustainable solvent system for cellulose was investigated. In this regard, a detailed optimization study of the DBU-CO2 switchable solvent system was performed using in-situ infrared spectroscopy. Upon optimization, up to 8 wt.% cellulose could be dissolve within 15 min at 30 °C using low CO2 pressure (2-5 bar). What makes this solvent system sustainable, when compared to other classical cellulose solvents, includes: easier recyclability by simple release of the CO2 pressure, fast and mild solubilization and lower cost compared to ionic liquids. Finally, by successfully trapping the formed in-situ cellulose carbonate using an electrophile, a clearer understanding of this solvent system was established.The successful optimization of a sustainable solvent system for cellulose led to the second part of the thesis: the regeneration of cellulose. Here, the general solubilization and coagulation ways followed by freeze-drying was adopted to prepare cellulose aerogels. Various processing conditions such as cellulose concentration, coagulating solvent and super base, were investigated on their effect of the aerogels properties (density, morphology, pore size). The obtained results showed aerogels with densities between 0.05 and 1.2 g/cm3, porosities between 92 and 97 % and pore sizes between 1.1 and 4.5 μm. In addition, from scanning electron microscopy (SEM), open large macroporous inter-connected cellulose networks were observed.The derivatization of cellulose to make thermally processable materials is covered in the third part of the thesis. This part is divided into two sub-parts; transesterification and multicomponent reaction modification. [...]
Als Kohlenstoffquelle mit der größten Verfügbarkeit auf unserem Planeten, ohne Konkurrenz zur Lebens- und Futtermittelversorgung, stellt Cellulose eine interessante Alternative dar, um die vielfältig genutzten, nicht-nachhaltigen Polymere auf Erdölbasis zu ersetzen. Die Mehrheit der Forscher, die mit diesem faszinierenden Biopolymer arbeiten, vernachlässigt allerdings Überlegungen zur Nachhaltigkeit in die chemische Modifizierung von Cellulose bei der Herstellung von Materialien zu integrieren. Die Konsequenz dessen ist eine Verlagerung der Umweltbelastung auf andere Abschnitte des Prozess-Zyklus. Um Nachhaltigkeit sicherzustellen, sind deshalb sowohl der erneuerbare Aspekt von Cellulose als auch Überlegungen zur Nachhaltigkeit im Reaktionsprozess wichtig. Dies beinhaltet die Berücksichtigung des Lösungsmittels, die Reaktanden, des Derivatisierungsprozesses, die produzierten Abfälle sowie eine Beurteilung der Nachhaltigkeit der resultierenden Produkte, die relevante Eigenschaften aufweisen müssen um mit bestehenden Alternativen konkurrieren zu können. Diese Arbeit ist deshalb in drei Teile gegliedert (Löslichkeit, Rückgewinnung und Derivatisierung von Cellulose) und befasst sich mit den verschiedenen Aspekten der Nachhaltigkeit während der Umsetzung von Cellulose mit dem Ziel, verarbeitbare Materialien herzustellen.Im ersten Teil der Arbeit wurde ein nachhaltiges Lösungsmittelsystem für Cellulose untersucht. In diesem Zusammenhang wurde eine detaillierte Optimierungsstudie des DBU-CO2 schaltbaren Lösungsmittelsystems mittels in-situ Infrarot Spektroskopie durchgeführt. Nach der Optimierung konnten bis zu 8 Gew.-% Cellulose innerhalb von 15 min. bei 30°C und einem niedrigen CO2-Druck (2-5 bar) gelöst werden. Verglichen mit klassischen Lösungsmitteln für Cellulose weist dieses Lösungsmittelsystem verschiedene nachhaltige Aspekte auf: Einfaches Recycling durch entfernen des CO2-Drucks, schnelles und mildes Auflösen und geringere Kosten als ionische Flüssigkeiten. Durch erfolgreiches Abfangen des in-situ gebildeten Cellulose-Carbonats mit einem Elektrophil, konnte schließlich ein besseres Verständnis dieses Lösungsmittelsystems erreicht werden. Die erfolgreiche Optimierung eines Lösungsmittelsystems für Cellulose führte zum zweiten Teil der Arbeit: der Regenerierung von Cellulose. Hier wurde der bereits mit anderen Systemen beschriebene Weg von Lösen und Ausfällen, gefolgt von Gefriertrocknen übernommen, um Cellulose-Aerogele herzustellen. Verschiedene Bedingungen bei der Verarbeitung wie die Cellulose-Konzentration, Lösungsmittel zum Ausfällen und die Superbase und deren Effekt auf die Eigenschaften der Aerogele (Dichte, Morphologie und Porengröße) wurden untersucht. So wurden Aerogele mit einer Dichte von 0.05-1.20 g/cm3, Porositäten zwischen 92 und 97% und Porengrößen zwischen 1.1 und 4.5 μm erhalten. Zusätzlich wurden im Rasterelektronenmikroskop offene große und makroporöse, miteinander verbundene Cellulose-Netzwerke beobachtet. [...]

Les hétérocycles azotés ont toujours retenu l’attention des chimistes du fait de leurs potentielles activités biologiques mais également pour leurs grandes occurrences dans les produits naturels. De ce fait émerge la nécessité de développer de nouvelles méthodes de synthèse innovantes permettant un accès rapide et efficace à ces hétérocycles. C’est dans cette philosophie que s’inscrivent ces travaux de thèse dont l’objectif est le développement de nouvelles approches basées sur l’utilisation de réactions d’ammoniumation catalysées à l’or(I) afin d’induire des cascades réactionnelles donnant accès à une large variété d’hétérocycles azotés. Ainsi, un motif de base N-sulfonyl-2-(1-propargyl)azétidine a permis d’accéder à une large variété de dérivés pyrroliques et de tétrahydroazépines. L’extension du concept d’ammoniumation lors de l’utilisation des N-(2-alcynylaryl)sulfonyl azétidines a conduit à l’obtention de benzosultames. Un autre défi majeur de la chimie de synthèse moderne est l’obtention de molécules énantiopures. Pour répondre à cette problématique, de nouveaux complexes chiraux NHC platine(II) ont été synthétisés et évalués en tant que catalyseurs sur des réactions de cycloisomérisation
Nitrogen-containing heterocycles have always retained the attention of chemists considering their potent biological properties as well as their large occurrence in natural product structures. Therefore, the development of new innovative synthetic methods that allow a rapid and efficient access to these heterocycles is highly sought. It is in this philosophy that these PhD works take place, whose aims at the development of new approaches based on gold(I) catalyzed ammoniumation reactions in order to trigger cascade reactions and to reach important nitrogen-containing heterocycles. The N-sulfonyl-2-(1-propargyl) azetidine scaffold allows formation of a large variety of pyrroles and tetrahydroazepines derivatives. The extension of the concept of ammoniumation by using N-(2-alcynylaryl)sulfonyl azetidines allowed the formation of benzosultam derivatives. Another major challenge of modern synthetic chemistry is the formation of enantiopur molecules. To reach this goal, new chiral NHC platinum (II) complexes have been synthesized and evaluated as catalysts for cycloisomerization reactions