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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Complexes dinucléaires Ruthénium-cyanamides : composés modèles pour l'étude de la communication électronique à longue distance

Fabre, Muriel 30 June 2006 (has links) (PDF)
La communication électronique dans des complexes dinucléaires du ruthénium peut être caractérisée soit par le couplage électronique Vab dans le système à valence mixte (RuII-RuIII), soit par le couplage magnétique J dans le système homovalent paramagnétique (RuIII-RuIII). L'objectif de ce travail était d'obtenir une famille de composés en faisant varier la longueur du ligand pontant et de mesurer les interactions électronique et magnétique afin d'établir une corrélation entre J et Vab.<br />Une première famille de complexes dinucléaires du ruthénium [{RuII(tpy)(acac)}2(µ-L)] (où tpy = 2,2'-6',2''-terpyridine, acac = acétylacétonate et L est un ligand pontant dicyanamide) a été synthétisée. Ces complexes, bien que prometteurs pour la mesure des couplages électroniques et magnétiques, n'ont pas pu être caractérisés et étudiés complètement en raisons des problèmes de solubilité rencontrés.<br />Une deuxième famille de composés [{RuII(tpy)(thd)}2(µ-L)] (où thd = 2,2,6,6-tétraméthylheptanedione), plus solubles de par la présence de groupements tert-butyles, a ensuite été synthétisée, la distance métal-métal variant entre 12,0 et 25,1 Å. Les formes à valence mixte RuII-RuIII de ces complexes ont été générées par électrochimie et le couplage électronique Vab déterminé par spectroscopie UV-Vis-Proche IR. On retrouve une décroissance exponentielle de ce paramètre avec la distance métal-métal. Les formes homovalentes paramagnétiques RuIII-RuIII ont été générées chimiquement et/ou électrochimiquement, des mesures de susceptibilité magnétique et des études RPE ont permis la détermination du paramètre de couplage magnétique J et la mise en évidence d'une loi de décroissance exponentielle de ce paramètre avec la distance métal-métal.<br />Le complexe le plus court de cette famille [{RuII(tpy)(thd)}2(µ-dicyd)] (où dicyd = dicyanamidobenzène) présente un comportement très différent. Des études électrochimiques, spectroscopiques (UV-Vis-PIR, RPE), magnétiques et cristallographiques complétées par des calculs DFT ont mis en lumière la non-innocence du ligand dicyanamidobenzène dans ce type de systèmes. En l'occurrence, celui-ci est oxydé avant les deux ions ruthénium (II).
12

Produção da videira Niagara Rosada submetida a indutores de brotação, no Oeste do Paraná / Production of Niagara Rosada grapevine submitted to sprouting inducers, in Western Paraná

Werle, Tatiana 14 August 2011 (has links)
Made available in DSpace on 2017-07-10T17:37:44Z (GMT). No. of bitstreams: 1 Tatiana_Werle.pdf: 502997 bytes, checksum: a8ed05a8a76d34c68e008dc33707334a (MD5) Previous issue date: 2011-08-14 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In an attempt to induce the grapevines buds sprouting in mild winter regions, characterized by mild temperatures during the hibernal season, it becomes necessary the use of sprouting inducers. Considering the grapevines cultivation expansion in Western Paraná, the current study had as its aims to determine the optimal concentration of hydrogenated cyanamide, ethephon and Stimulate® bio-stimulant for the induction and uniformity of sprouting in Niagara Rosada cultivar, as well to indicate the most effective product in the uniformity sprouting inducing and which promotes improved productivity and fruits quality. The experiment was conducted in a commercial vineyard located in the municipality of Quatro Pontes, West of Paraná State. The experiment was carried out in outlined blocks in factorial scheme 3 X 5, totaling 15 treatments with four repetitions, and each plant was considered an experimental unit. The treatments consisted of the following concentrations: 0; 10 mL L-1; 20 mL L-1; 30 mL L-1 and 40 mL L-1 of hydrogenated cyanamide (H2CN2); 0 ; 2 L ha-1; 4 L ha-1; 6 L ha-1 and 8 L ha-1 of ethephon; 0; 5 mL L-1; 10 mL L-1; 15 mL L-1 and 20 mL L-1 Stimulate® bio-stimulant. The products application was made immediately after pruning, by spraying with backpack sprayer. After pruning, it was assessed the number of buds per plant, time to sprouting onset after application, number and percentage of sprouting per plant, production per plant, expected productivity, average weight of berries, number of berries per cluster, width of shoulder and berries, berries length, soluble solids content, titration total acidity, pH and ratio. Considering the conditions under which the experiment was conducted, one can conclude that: The concentration of hydrogenated cyanamide which showed higher percentage of 'Niagara Rosada' grapevine sprouted buds was the 20mL L-1; the ethephon concentration which provided the highest percentage of Niagara Rosada grapevine sprouted buds was the 8 L ha-1; the bio-stimulant concentration which provided the highest percentage of Niagara Rosada grapevine sprouted buds was the 5 mL L-1; the hydrogenated cyanamide provided the anticipation and uniformity of the Niagara Rosada grapevine sprouting. The buds spraying with hydrogenated cyanamide, ethephon and bio-stimulant resulted in no effect on the grapevine productivity and quality, cv. Niagara Rosada / Na tentativa de induzir a brotação das gemas de videiras em regiões de inverno ameno, caracterizado por temperaturas suaves durante a estação hibernal, torna-se necessário o emprego de indutores de brotação. Considerando a expansão do cultivo de videiras no Oeste do Paraná, o presente trabalho teve como objetivos verificar a concentração ideal de cianamida hidrogenada, ethephon e do bioestimulante Stimulate® para a indução e uniformização de brotação na cultivar Niagara Rosada, bem como indicar o produto mais eficiente na indução de uniformização de brotação e que promove melhor produtividade e qualidade de frutos. O experimento foi conduzido em vinhedo comercial localizado no município de Quatro Pontes, Oeste do Estado do Paraná. O experimento foi implantado em delineamento de blocos em esquema fatorial 3 X 5, totalizando 15 tratamentos com quatro repetições, sendo que cada planta foi considerada uma parcela experimental. Os tratamentos foram compostos pelas seguintes concentrações: 0; 10 mL L-1; 20 mL L-1; 30 mL L-1 e 40 mL L-1 de cianamida hidrogenada (H2CN2); 0; 2 L ha-1; 4 L ha-1; 6 L ha-1 e 8 L ha-1 de ethephon; 0; 5 mL L-1; 10 mL L-1; 15 mL L-1 e 20 mL L-1 de bioestimulante Stimulate®. A aplicação dos produtos foi feita imediatamente após a poda, através de pulverização com pulverizador costal. Após a poda avaliou-se o número de gemas por planta, tempo para início da brotação após a aplicação, número e porcentagem de brotações por planta, produção por planta, produtividade esperada, massa média das bagas, número de bagas por cacho, largura do ombro e das bagas, comprimento das bagas, teor de sólidos solúveis, acidez total titulável, pH e ratio. Considerando as condições em que foi conduzido o experimento pode-se concluir que: A concentração de cianamida hidrogenada que proporcionou maior porcentagem de gemas brotadas de videira Niagara Rosada foi a de 20 mL L-1; A concentração de ethephon que proporcionou maior porcentagem de gemas brotadas de videira Niagara Rosada foi a de 8 L ha-1; A concentração de bioestimulante que proporcionou maior porcentagem de gemas brotadas de videira Niagara Rosada foi a de 5 mL L-1; A cianamida hidrogenada proporcionou a antecipação e uniformização das brotações de videira Niagara Rosada. A pulverização das gemas com cianamida hidrogenada, ethephon e bioestimulante não resultou em efeito sobre a produtividade e qualidade de videira, cv. Niagara Rosada
13

Palladium(II)-Catalyzed Addition Reactions : Synthesis of Aryl Amidines and Aryl Ketones

Rydfjord, Jonas January 2017 (has links)
Palladium-catalyzed reactions have become one of the most important tools in modern organic chemistry due to its ability to catalyze the formation of new carbon-carbon bonds. The aim of the work presented in this thesis was to develop new palladium(II)-catalyzed addition reactions. In this work, cyanamides were investigated as a new substrate to give aryl amidines as products. The first protocol developed employed aryltrifluoroborates as the aryl partner, and the insertion of the aryl group into un-, mono-, and di-substituted cyanamides was successful for a wide variety of aryltrifluoroborates. An alternative method of generating the necessary intermediate for insertion into the cyanamide is the decarboxylative formation of aryl-palladium from aryl carboxylic acids. A protocol was developed for this reaction, but was unfortunately limited to a small number of ortho-substituted electron-rich aryl carboxylic acids. The mechanism was investigated by the means of DFT calculations and ESI-MS studies, and the rate-determining step was suggested to be the 1,2-carbopalladation based upon those results. A translation of the batch protocol to continuous-flow conditions was also demonstrated. The ideal method of generating the aryl-palladium species is by C-H bond activation, and this approach was demonstrated with indoles, giving a variety of 3-amidinoindoles as products. The mechanism was investigated by DFT calculations and a plausible catalytic cycle was proposed. A continuous-flow application of a desulfitative palladium(II)-catalyzed addition to nitriles to give ketones was developed. In addition, different reactor materials were evaluated in the microwave heated reactor cavity. Thus the reaction was shown to proceed with microwave heating in a borosilicate glass and an aluminum oxide reactor, and also in conditions mimicking conventional heating in a silicon carbide reactor. Finally, a protocol was developed for the convenient synthesis of sodium aryl sulfinates from Grignard and lithium reagents using a solid sulfur dioxide source as a safe alternative to the gas. The products of this protocol can be used as aryl-palladium precursors by a desulfitative process.
14

Nouvelles exploitations des tétrazoles comme précurseurs en synthèse organique: accès aux morpholines, cyanamides et produits naturels

Duchamp, Edouard 01 1900 (has links)
Les cycles azotés font partie intégrante de la vie sur Terre. Cette thématique est transcrite dans les travaux de cette thèse à travers les tétrazoles et les morpholines. Les morpholines sont des azacycles saturés possédant de nombreuses propriétés physico-chimiques et structurales intéressantes, ce qui en fait un motif de choix en chimie médicinale. L'essor des morpholines est d'autant plus important que les industries pharmaceutiques tendent à limiter l'utilisation de cycles insaturés au profit de motifs permettant des structures plus complexes et occupant les trois dimensions de l'espace. Ainsi, le développement de nouvelles voies d'accès aux morpholines est contemporain. La contribution présentée dans ce manuscrit s'appuie sur la réduction de tétrazoles oxabicycliques par des hydrures. Le mécanisme du clivage réductif du tétrazole en amine a par ailleurs été étudié et élucidé. Les cyanamides forment un groupement fonctionnel intéressant grâce à leur nature électronique ambivalente. Elles sont de plus en plus utilisées en chimie médicinale en tant qu'inhibiteurs covalents. Alors que les cyanamides ont été découvertes à l'aube de la chimie organique, leurs synthèses ont traditionnellement eu recours à des sources de cyanure, composé extrêmement toxique. La métallation en position 5 des tétrazoles 1-substitués permet d'induire la rétrocyclisation spontanée conduisant à l'expulsion d'une molécule de diazote et d'un sel de cyanamidure. Ce sel a pu être isolé ou alkylé in situ, offrant une nouvelle voie d'accès aux cyanamides sans source de cyanure. Les cyanamides ainsi obtenues ont pu être diversifiées en amidines par addition d'organolithiens. La Polygonapholine est un alcaloïde contenant une morpholine 2,6-disubstituée isolé en 1997. La structure rapportée est probablement erronée et seule une synthèse en laboratoire peut confirmer son exactitude. Ainsi, la première synthèse totale de ce produit naturel a été débutée et est présentée dans le dernier chapitre de ce manuscrit. / Nitrogen-containing rings are core entities in the living world. This theme is conveyed in the manuscript through tetrazoles and morpholines. Morpholines are saturated azacycles possessing numerous physico-chemical and structural properties, which makes them a motif of interest in medicinal chemistry. The impact of morpholines is even more important as pharmaceutical industries try to avoid overuse of unsaturated rings in favor of saturated motifs that allow for more complex structures in the three dimensions. Therefore, development of new methods to access morpholines is an ongoing activity in many laboratories. The approach presented herein relies on the hydride reduction of oxabicyclic tetrazoles to morpholines. A detailed mechanism of the reductive cleavage of the tetrazole unit is presented. Cyanamides are endowed with an ambident electronic character that adds value to this functional group. They are widely used in drug design as covalent inhibitors. Even though cyanamides were discovered in late 19th century, their synthesis has traditionally relied on the cyanation of amines using toxic cyanide reagents. 1-Substituted 5-metalotetrazoles undergo rapid cycloreversion releasing dinitrogen and forming N-metalated cyanamide salts. The salts can be isolated or alkylated in situ, providing a new method for accessing cyanamides without the use of cyanide reagents. The obtained cyanamides could be subjected to an addition reaction with organolithium reagents, thereby yielding novel amidines. The alkaloid Polygonapholine is a 2,6-disubstituted morpholine isolated in 1997. The reported structure has never been confirmed, nor has the natural product been synthesized in the laboratory. Efforts towards its total synthesis and stereochemical confirmation is presented in the last chapter of the thesis.
15

Voies alternatives de traitement pour l'obtention de papiers résistants à l'état humide et de textiles cellulosiques infroissables / Alternative ways to obtain paper with wet-strength and wrinkle resistant cellulosic textiles

Ben Fadhel, Besma 13 November 2012 (has links)
Cette thèse comporte un volet papetier et un volet textile. Dans le premier volet, de nouveaux produits capables d’améliorer la résistance à l’état humide (REH) du papier et qui soient si possible ‘écologiques’ ont été recherchés. Dans ce but, nous avons synthétisé avec de bons rendements des sels d’ammoniums quaternaires (SAQs) allylés dont beaucoup sont originaux. Ces sels ont été par la suite polymérisés à l‘aide d’un réacteur micro-onde. Les polymères obtenus sont cationiques, hydrosolubles et amphiphiles. Après fixation sur papier, nous avons mis en évidence qu’un traitement bicouche avec un copolymère amphiphile à base de bromure N,N-diallyl-pyrrolidinium (BDAP) et de carboxyméthylcellulose (CMC) apporte de façon inattendu un caractère hydrophobe marqué au papier traité alors que des copolymères réactifs synthétisés à base de N,N-diallyl-3-hydroxy-azétidinium (CDAHA) sont capables de conférer au papier une REH comparable à celle fournie par les résines polyamide-amine-épichlorhydrine (ou PAE) commerciales. Concernant le volet textile, l’objectif était de produire une recette optimale de traitement infroissable pour un tissu 100% coton à base d’acides polycarboxyliques, qui soit performante, non onéreuse et écologique. Pour cela, nous avons choisi l’acide citrique (AC) comme étant l’élément actif de la recette qui est à base de 5% d’AC et d’un mélange de catalyseurs : hypophosphite de sodium / cyanamide (1 éq ; 0,75 : 0,25). La température et le temps de réticulation ont été optimisés respectivement à 170°C et 90 s. L’infroissabilité ainsi conférée peut être estimée au mieux à assez bonne. En contrepartie, ce traitement infroissable engendre une dégradation de la résistance à la traction et du degré de blanc du support. Des supports de coton traités avec la recette optimale et éventuellement d’autres recettes ont été caractérisés par différentes méthodes analytiques. Les résultats trouvés montrent que la réaction d’estérification de la cellulose avec l’AC se produit principalement dans la paroi cellulaire et non pas en surface des fils de coton. En outre, le degré de polymérisation de la cellulose traité chute de 60%, ce qui est en accord avec les mesures dynamométriques déjà réalisées. / This work is divided into two parts: a papermaking part and a textile one. In the first part, new and if possible ‘green’ products, which can improve paper wet-strength, have been designed. For this purpose, unsaturated quaternary ammonium salts (SAQs), many of them unpublished so far, were synthesized. These salts were then polymerized using a microwave reactor. The resulting (co)polymers are cationic, water-soluble and amphiphilic. We demonstrated that papers, once treated by an amphiphilic N,N-diallyl-pyrrolidinium-based copolymer and carboxymethylcellulose (CMC) via a bi-layer treatment, were endowed with an obvious hydrophobic character. Moreover, other copolymers synthesized from N,N-diallyl-3-hydroxy-azetidinium (CDAHA) were able to impart to paper sheet a wet-strength comparable to that usually provided by polyamide-amine-epichlorohydrin (PAE) resins. The second part of the present work is dedicated to the development of an optimal anti-wrinkle recipe for cotton fabrics based on polycarboxylic acids. This recipe should be ideally efficient, cheap and eco-friendly. For that goal, citric acid (CA) was used as the active medium of the recipe that was based on 5% aq AC (w/w) solution and a catalyst mixture: sodium hypophosphite / cyanamide (1 eq, 0.75, 0.25). Temperature and heating duration was respectively optimized at 170°C and 90 s. Resulting crease-resistant properties can be estimated at best to good. However, such an anti-wrinkle treatment causes a degradation of both tensile strength and whiteness index. Cottons treated with the optimum recipe and other recipes were characterized by different analytical methods. Data showed that esterification reaction of cellulose with AC occurs mainly in the cell wall and does not affect the yarn surface. In addition, polymerization degree of treated cellulose was reduced of 60% in accordance with already measured mechanical properties.

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