Part I Studies on methodology development of the syntheses of carboline derivatives using Bischler-Napieralski reaction and electror-eduction gave moderate yields. Carbolines were undergone Mannich reaction to give yohimbane alkaloids. We got oxidative carboline products using Bischler-Napieralski reaction. We got carbolines or dimmer by the reaction of electroreduction in different condition. Part II Phenylacetamides using Bischler-Napieralski reaction conditions with acetonitrile as a solvent, gave the 3-amino-isoquinolines. Various amides and various nitriles were undergone Bischler-Napieralski reaction conditions to give 3-aminoiso-quinoline products.

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Part1: Application of electrooxidation reaction toward the synthesis of atropine allcaloids and synthesis of cocaine alkaloids. Part2: Application of electroreduction reaction toward the synthesis of yohimbine alkaloids.

In the last few years the quest towards a hydrogen based economy has intensified interest for effective and less expensive catalysts for fuel cell applications. Due to its slow kinetics, alternative catalysts for the oxygen electroreduction reaction are actively researched. Platinum alloys with different transition metals (for example: Ni, Co and Fe) have shown improved activity over pure Pt. The design of a Pt-free catalysts is also highly desirable, and different alternatives including metalloporphyrins and Pd-based catalysts are being researched. Pd-based catalysts constitute an attractive alternative to Pt alloys in some fuel cell applications, not only because of lower costs but also because of the lower reactivity of Pt alloys towards methanol, which is important for improved methanol crossover tolerance on direct methanol fuel cells. In this work we apply density functional theory (DFT) to the study of four catalysts for oxygen electroreduction. The electronic structure of these surfaces is characterized together with their surface reconstruction properties and their interactions with oxygen electroreduction intermediates both in presence and absence of water. The energetics obtained for the intermediates is combined with entropy data from thermodynamic tables to generate free energy profiles for two representative reaction mechanisms where the cell potential is included as a variable. The study of the barriers in these profiles points to the elementary steps in the reaction mechanisms that are likely to be rate-determining. The highest barrier in the series pathway is located at the first proton and charge transfer on all four catalytic surfaces. This is in good agreement with observed rate laws for this reaction. The instability of hydrogen peroxide on all surfaces, especially compared with the relatively higher stability of other intermediates, strongly points at this intermediate as the most likely point where the oxygen bond is broken during oxygen reduction. This adds to the argument that this path might be active during oxygen electroreduction. A better understanding behind the reaction mechanism and reactivities on these representative surfaces will help to find systematic ways of improvement of currently used catalysts in the oxygen electroreduction reaction.

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Ce travail de thèse s'inscrit dans le cadre de la valorisation du CO2 par voie électrochimique. Il est consacré en grande partie à l'élaboration et l'étude physico-chimique d'électrodes à diffusion de gaz (GDE), dans le but de mieux comprendre les mécanismes et les paramètres déterminants pour l'électrocatalyse de la réduction du CO2 avec ce type d'électrodes poreuses. Cette étude est articulée autour de deux axes principaux, le premier concerne des catalyseurs métalliques et le second se focalise sur des catalyseurs moléculaires.Le premier axe est relatif à la préparation, la caractérisation et l'étude électrochimique de catalyseurs de Cu, Co, In, Zn, Bi, Fe et Pb supportés sur poudre de carbone poreux. La mise en œuvre de ces catalyseurs sous forme de GDE a été étudiée, ainsi que leur activité électrocatalytique vis-à-vis la réduction du CO2. En milieu aqueux, les GDE contenant de l'indium ont permis d'obtenir les meilleurs rendements faradiques pour l'électroréduction du CO2 en acide formique. Par comparaison avec une plaque métallique d'indium, les GDE-In/C montrent des performances catalytiques améliorées et une meilleure résistance aux impuretés de l'électrolyte. Nous avons montré, qu'en phase aqueuse, l'apport de CO2 gaz en continu à travers une GDE entraînait une amélioration de l'activité du catalyseur supporté. Ceci met en évidence l'intérêt d'utiliser des métaux sous forme de particules dispersées au sein d'une GDE plutôt que des électrodes métalliques massives.Le second axe de cette étude a fait appel à trois complexes dimère de ruthénium de formule générale [Ru(L)(CH3CN)(CO)2]2(PF6)2. L'étude des propriétés redox de ces précurseurs de catalyseurs contenant des ligands L (bipyridine) diversement substitués a permis de mettre en évidence la formation de polymères à liaisons Ru-Ru par électroréduction. Le ligand portant une fonction pyrrole permet, au préalable, la formation d'un film de polypyrrole conférant au catalyseur une meilleure stabilité et de meilleures performances catalytiques. Différentes stratégies d'immobilisation de ces complexes sur carbone poreux ont été utilisées pour obtenir des GDE modifiées. Cette étude a permis de mieux comprendre l'interaction entre le catalyseur moléculaire et le support lors de la réduction du CO2. Nous avons ainsi montré que l'activité électrocatalytique du catalyseur supporté sur GDE était maintenue en milieu aqueux.Parallèlement à ce travail fondamental, un pilote de laboratoire a été développé pour effectuer la réduction électrocatalytique du CO2 en phase gaz, afin de s'affranchir de limitations rencontrées en milieu aqueux, telles que la solubilité du CO2 et la séparation des produits de la réaction. Cette étude en cours de développement a permis d'identifier certains verrous, notamment la nature de la membrane échangeuse d'ions ainsi que la nature et la proportion du polymère électrolytique entrant dans la formulation de la couche catalytique. Ce travail apporte des connaissances fondamentales et des réponses concrètes qui permettront probablement qu'un tel procédé de valorisation du CO2 puisse constituer un jour un procédé viable à l'échelle industrielle. / This thesis concerns the valorization of CO2 by electrochemical means. It is largely devoted to the preparation and physico-chemical study of gas diffusion electrodes (GDE) in order to better understand the mechanisms and key parameters for electrocatalytic reduction of CO2 using this type of porous electrode. This study revolves around two main axes, the first is related to metal catalysts and the second is focused on molecular catalysts.The first axis deals with the preparation, characterization and electrochemical properties of Cu, Co, In, Zn, Bi, Pb and Fe catalysts supported on porous carbon powder. Their implementation to form GDE and their electrocatalytic activity toward CO2 reduction were studied. In aqueous medium, the GDE containing indium allowed obtaining the highest Faraday yields for electroreduction of CO2 to formic acid. In comparison with a metallic indium foil, the GDE-In/C showed improved catalytic performance and improved resistance to the electrolyte's impurities. We demonstrated that in the aqueous phase, a continuous flow of CO2 through a GDE resulted in an improved reactivity of the supported catalyst. This highlights the advantage of using dispersed metal particles on GDE rather than metal foil electrodes.The second axis of this study focuses on three dimeric ruthenium complexes with the general formula [Ru(L)(CH3CN)(CO)2]2(PF6)2. The study of the redox properties of these catalyst precursors containing variously substituted L (bipyridine) ligands, allowed the formation of polymer bonds of Ru-Ru by electroreduction to be demonstrated. The ligand with a pyrrole functional group allows for the prior formation of a polypyrrole film, conferring improved catalyst stability and enhancing the catalytic performance. Different ways of immobilizing the complex on porous carbon have been used to obtain modified GDE. This study provided insight into the interaction between the molecular catalyst and the catalyst carrier during the CO2 reduction. We have demonstrated that the electrocatalytic activity of the catalyst deposited on the GDE is maintained in an aqueous medium.Alongside this fundamental work, a laboratory pilot was developed to perform the electrocatalytic reduction of CO2 in the gas phase, in order to overcome limitations encountered in an aqueous medium, such as CO2 solubility and reaction products separation. This under development study has not only identified obstacles, including the nature of the ion exchange membrane, but has also identified the nature and proportion of the polymer electrolyte used in the formulation of the catalyst layer. This work has provided fundamental knowledge and concrete answers which probably allow one day that such a process as CO2 valorization may be viable on an industrial scale.

The price of crude glycerol has significantly decreased worldwide because of its oversupply. Many chemical and biological processes have been proposed to transform glycerol into numerous value-added products, such as glycolic acid, 1,3-propanediol (1,3-PDO), 1,2-propanediol (1,2-PDO), glyceric acid, and lactic acid. However, these processes suffer from several drawbacks, including high production cost. Therefore, in this study, a simple and robust electrochemical synthesiswas developed to convert glycerol into various value-added compounds. This study reports for the first time the use of Amberlyst-15 as a reaction mediumand redox catalyst for electrochemical conversion of glycerol. In the first part, the electrochemical performance of Amberlyst-15 over platinum (Pt)electrode was compared with that of conventional acidic (H2SO4) and alkaline (NaOH) media. Other parameters such as reaction temperature [room temperature (27°C) to 80 °C] and applied current (1.0 A to 3.0 A) were also examined. Under the optimized experimental condition, this novel electrocatalytic method successfully converted glycerol into glycolic acid after 8 h of electrolysis, with a yield of 45% and selectivity of 65%, as well as to glyceric acid after 3 h of electrolysis, with a yield of 27% and selectivity of 38%. In the second part of this study, two types of cathode electrodes, namely, activated carbon composite(ACC) and carbon black diamond (CBD) electrodes, were used in electrochemical conversion of glycerol. To the best of our knowledge, electrochemical studies of glycerol conversion using these electrodes have not been reported yet. Glycerol was also successfully reduced to lactic acid, 1,2-PDO, and 1,3-PDO, in addition to oxidation compounds (e.g. glycolic acid). Three operating parameters, namely, catalyst amount (6.4% to 12.8% w/v), reaction temperature [room temperature (27 °C) to 80 °C], and applied current (1.0 A to 3.0 A), were tested. In the presence of 9.6% w/v Amberlyst-15 at 2.0 A and 80 °C, the selectivity of glycolic acid can reach 72% and 68% (with yield of 66% and 58%) for ACC and CBD electrodes, respectively. Lactic acid was obtained as the second largest compound, withselectivity of 16% and yield of 15% for the ACC electrode and 27% selectivity and 21% yield for the CBD electrode. Finally, electro-oxidation and electroreduction of glycerol were performed in a two-compartment cell separated by a cation exchange membrane (Nafion 117). This study only focused on the electroreduction region. Three cathode electrodes (Pt, ACC, and CBD) were evaluated under the following conditions: 2.0 A, 80 °C, and 9.6% w/v Amberlyst-15. ACC demonstrated excellent performance in the electroreduction study and successfully reduced glycerol to 1,2-PDO, with a high selectivity of 85%. The selectivity of 1,2-PDO on Pt and CBD was 61% and 68%, respectively. Acetol and diethylene glycol were also obtained. The reaction mechanisms underlying the formation of these products are then proposed.

Avec les récents changements climatiques et la mutation de plusieurs secteurs industriels, une meilleure gestion des rejets de dioxyde de carbone (CO2) est fortement envisagée. De plus en plus d'intérêt est porté sur la valorisation de CO2 au lieu de son stockage simple. Ainsi, ce projet de thèse s'est focalisé sur l'utilisation de polyoxométallates (POMs) et plus particulièrement ceux substitués par des métaux de transition (TMS-POMs), pour la valorisation de CO2 via son électroréduction. Cette approche permet par la même occasion d'assurer une meilleure gestion de l'énergie électrique. Différentes structures de TMS-POMs ont été préparés, donnant des POM mono et polysubstitués aux métaux de transition simples, ainsi qu'un POM fonctionnalisé par un complexe organométallique actif pour l'électroréduction de CO2. Une approche synthétique originale a permis d'obtenir ce dernier complexe, ouvrant la voie à de nouveaux complexes actifs pour l'électroréduction de CO2. Les propriétés électrochimiques, ainsi que leurs aptitudes à catalyser l'électroréduction de CO2 ont été évaluées en différents milieux réactionnels. Une vue globale sur l'application potentielle de cette classe de complexe a ainsi été adopté, montrant notamment la capacité de ces complexes de mener la réduction à 4 électrons et 4 protons de CO2 en formaldéhyde. / With the recent climate change issues and the recent industrial evolutions, a better management of carbon dioxide (CO2) releases is highly demanded. More and more research is focused on CO2 industrial uses rather than its mere storage. Thus, this PhD project deals with the use of polyoxometalates (POMs), especially transition metals substituted ones (TMS-POMs), for CO2 conversion through its électroréduction. This approach allows both a better electrical power and CO2 release management. Different TMS-POMs structures were prepared, yielding mono and polysubstituted POM with simple transition metal and also functionalized ones with active organometallic complex for CO2 électroréduction. An original synthetic approach allowed us to achieve this late functionalization, opening the way for new catalysts for CO2 conversion. Theirs electrochemical properties, as well as their ability to catalyze CO2 électroréduction were investigated in different reaction media. An overview on the potential application of this complex class has been adopted. Noticeably, it highlighted the ability of these complexes to carry out the 4-electrons and 4-protons reduction of CO2 to formaldehyde.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15375号 / 工博第3254号 / 新制||工||1490(附属図書館) / 27853 / 京都大学大学院工学研究科原子核工学専攻 / (主査)教授 森山 裕丈, 教授 山名 元, 准教授 佐々木 隆之 / 学位規則第4条第1項該当

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