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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.
321

Estudos da diastereosseletividade da adição de nucleófilos ao grupo carbonila de β-cetossulfóxidos sulfanilados derivados da 1-indanona e 1-tetralona / On the diastereoselectivity of the addition of nucleophiles to 1- indanone and 1- tetralone sulfanylated β-ketosulfoxides

Paiva, Derisvaldo Rosa 17 June 2011 (has links)
Neste trabalho, foi proposta a preparação e redução, seguida de hidrólise oxidativa, de alguns derivados imínicos da 2-metilsulfinil-2-metilsufanil-1-tetralona e da 2-metilsulfinil-2-metilsulfanil-1-indanona. A 2-metilsulfinil-O-metil-oxima da 1-tetralona foi preparada pela oxidação da 2-metilsulfanil-O-metil-oxima. O sulfóxido assim obtido pôde ser sulfanilado empregando-se terc-butil lítio e metanotiolsulfonato de metila, resultando um único diastereoisômero que se mostrou inerte na reação de redução da função imínica com NaBH4. Tentativas de preparar a N-tosil-imina da 2-metilsulfinil-1-tetralona, por oxidação do sulfeto correspondente, não conduziram ao produto esperado, mas sim à enamina. Buscando uma rota alternativa para a preparação de derivados imínicos de sulfinil ciclanonas sulfaniladas, foram preparados β-cetossulfóxidos derivados da 1-tetralona e da 1-indanona que, após serem sulfanilados, seriam submetidos às reações com aminas aromáticas ou alifáticas. As reações de sulfanilação da 2-metilsulfinil-1-indanona e da 2-metilsulfinil-1-tetralona foram efetuadas em condições de transferência de fase, na presença dos catalisadores TEBAC ou QUIBEC. Para ambos os casos, os rendimentos de produto foram cerca de 80 %. Enquanto os dois catalisadores conduziram a resultados estereoquímicos similares para a sulfanilação da 2-metilsulfinil-1-indanona, para a 2-metilsulfinil-1-tetralona, o uso do catalisador quiral QUIBEC resultou em um aumento da diastereosseletividade da reação, no sentido da formação do diastereoisômero majoritário de configuração relativa CR,SR. Foram também efetuadas as reações de sulfanilação das duas 2-metilsulfinil ciclanonas em meio homogêneo, empregando como bases o hidróxido de lítio ou o di-isopropil amideto de magnésio. Porém, as reações das sulfinil ciclanonas sulfaniladas assim preparadas com a anilina e com a metil-amina não foram bem sucedidas. As reações de redução com boroidreto de sódio das duas sulfinil ciclanonas sulfaniladas conduziram aos respectivos álcoois em cerca de 70 % de rendimento e na forma de um único diastereoisômero, de configuração relativa SR,C-1R,C-2R, no caso do tetralol. As duas metilsulfinil ciclanonas sulfaniladas, opticamente ativas, foram preparadas em bons rendimentos, mas sob forma escalêmica, o que não permitiu o prosseguimento do estudo do curso estereoquímico da redução da carbonila de tais compostos. A reação de adição do enolato de lítio do acetato de etila à 2-metilsulfinil-2-metilsulfanil-1-indanona conduziu ao produto esperado em bom rendimento, mas com baixo excesso diastereoisomérico. Em condições análogas, a 2-metilsulfinil-2-metilsulfanil-1-tetralona mostrou-se inerte. / The original proposal of this research work was to prepare imines of 2-methylsulfinyl-2-methylsulfanyl-1-tetralone and 2-methylsulfinyl-2-methylsulfanyl-1-indanone that would be subsequently reduced and submitted to oxidative hydrolysis. By oxidation of 2-methylsulfanyl-1-tetralone-O-methyloxime the corresponding sulfoxide could be prepared, and submitted to the sulfanylation reaction using tert-butyllittium/methyl methanethiolsulfonate. The resulting product was obtained as a single diastereoisomer but showed to be unreactive towards reduction using sodium borohydride In attempting to convert the 2-methylsulfanyl-1-tetralone into the corresponding sulfoxide by oxidation, the corresponding sulfinylenamine was obtained instead of the expected sulfinylimine. Searching for an alternative synthetic route to the desired imines, the required β-ketosulfoxides were prepared and sulfanylated under phase-transfer catalysis using TEBAC or QUIBEC, as catalysts. In both cases, product yield was ca. 80%. Although for the sulfanylation of 2-methylsulfinyl-1-indanone using either TEBAC or QUIBEC the same diastereoselectivity was observed, for the reaction performed with 2-methylsulfinyl-1-tetralone and QUIBEC an improved diastereoselectivity was observed, in favour of the CR,SR diastereoisomer. Analogous sulfanylation reactions were performed in homogeneous medium in the presence of lithium hydroxide or magnesium diisopropylamide acting as bases. However, the reactions of the prepared 2-metylsulfinyl-2-methylsulfanyl ciclanones with aniline or methylamine were unsuccessful. The borohydride reduction of the 2-metylsulfinyl-2-methylsulfanyl ciclanones afforded the corresponding diastereoisomerically pure alcohols in ca. 70% yield, bearing, in the case of the tetralol derivative, the SR,C-1R,C-2R relative configuration. The two optically active sulfanylated 2-methylsulfinyl ciclanones could be prepared in good yields but as a scalemic mixture that precluded further studies in order to determine the stereochemical course of the carbonyl reduction. As for the addition reaction of the ethyl acetate lithium enolate to 2-methylsulfinyl-2-methylsulfanyl-1-indanone, the expected adduct was obtained in good yield but with poor diastereoselectivity. Under the same experimental conditions, the 2-methylsulfinyl-2-methylsulfanyl-1-tetralone underwent no reaction.
322

Benzo[5]radialenos como precursores de fluorenos e benzo[b]fluorenos / Benzo[5]radialenes as precursors of fluorenes and benzo[b]fluorenes

Von Richthofen, Andreas Albert 03 July 2015 (has links)
Neste trabalho demonstramos a preparação de fluorenos e benzo[b]fluorenos por uma nova rota sintética, baseada na reação de Diels-Alder de derivados benzo[5]radialênicos. Para a preparação destes últimos investigamos diversas estratégias, partindo de p-benzoquinona e três dienos: 1,1-dimetoxiciclopentadieno, 6,6-dimetilfulveno e 6-acetoxifulveno. A partir de cada fulveno obtivemos um benzo[5]radialeno diferente, sendo que o derivado dimetilado se mostrou inerte como dieno em cicloadições. O benzo[5]radialeno derivado do 6-acetoxifulveno, reagiu com diversos dienófilos tais como p-benzoquinona, 2,3-dicloro-p-benzoquinona, 1,4-naftoquinona, N-metilmaleimida, acetilenodicarboxilato de dimetila, acrilato de metila, etc. Notamos uma alta quimiosseletividade entre os sistemas diênicos, pois obtivemos apenas adutos trans. Com alguns dienófilos observamos a formação de compostos aromatizados (formados pela eliminação de ácido acético que, para os casos pertinentes, foi regiosseletiva). Com dienófilos como acrilato de metila ou sulfinil-naftoquinonas, alta regiosseletividade foi observada. Tentamos explorar tais seletividades para a preparação de análogos da eucapsitriona. Os adutos de Diels-Alder obtidos constituem exemplos de derivados fluorênicos e benzo[b]fluorênicos que, ultimamente, têm recebido grande atenção tanto por aspectos estruturais como por apresentarem propriedades biológicas importantes / In this work we demonstrated the preparation of fluorenes and benzo[b]fluorenes by a new synthetic route, based on the Diels-Alder reaction of benzo[5]radialenes derivatives. For the preparation of the last we investigated several strategies starting from p-benzoquinone and three dienes: 1,1-dimethoxycyclopentadiene, 6,6-dimethylfulvene and 6-acetoxyfulvene. From each fulvene we obtained a different benzo[5]radialene, but the dimethylated one showed no reactivity in cycloadditions. The benzo[5]radialene prepared from 6-acetoxyfulvene reacted with several dienophiles such as p-benzoquinone, 2,3-dichloro-p-benzoquinone, 1,4-naphtoquinone, N-methylmaleimide, dimethyl acetylenedicarboxylate, methyl acrylate, etc. We noted a high quimiosselectivity between the dienic sub units since only trans adducts were obtained. With some dienophiles we observed the formation of aromatized compounds (formed by acetic acid elimination which, for suitable cases, was regiosselective). With dienophiles such as methyl acrylate or sulfinyl-naphtoquinones high regiosselectivity was observed. We tried to explore such selectivities to prepare eucapsitrione analogues. These Diels-Alder adducts are examples of fluorenic and benzo[b]fluorenic derivatives, compounds that have gained considerable attention due to structural and biological aspects.
323

Análise da influência de condições experimentais sobre o comportamento eletroquímico e a distribuição dos produtos da oxidação eletroquímica de glicerol / Analysis of the influence of experimental conditions on electrochemical behavior and the distribution of products obtained by electrooxidation of glycerol

Teixeira, Wanderson Sirley Reis 14 August 2015 (has links)
O glicerol, 1,2,3-propanotriol, é o principal subproduto da indústria do biodiesel, cerca de 10% em massa. Apesar das inúmeras aplicações que o glicerol tem na indústria, a oferta desse poliálcool, devido ao grande aumento da produção de biodiesel nos últimos anos, tem crescido tanto que o produto tem se acumulado nas usinas, levando a um desequilíbrio entre produção e consumo. Dessa forma, muita pesquisa vem sendo feita na tentativa de utilizar essa abundante, barata e não tóxica matéria prima como base para a obtenção de energia e outros produtos de maior valor agregado. Dentre os vários processos para a conversão do glicerol, a eletro-oxidação recebe atenção especial devido à sua versatilidade, simplicidade e baixo custo. Neste trabalho, utilizou-se a voltametria cíclica para a análise do comportamento eletroquímico do glicerol e dos possíveis produtos obtidos pela sua eletro-oxidação sobre diversos eletrodos e a influência de variáveis experimentais, tais como, solvente, eletrólito de suporte, concentrações de substrato e eletrólito de suporte, na atividade eletrocatalítica do sistema. As técnicas de eletroforese capilar, coulometria e voltametria cíclica foram utilizadas para a determinação da taxa de conversão e análise quantitativa do glicerol e dos produtos obtidos por meio de eletrólise exaustiva e como esses parâmetros são influenciados pelas variáveis experimentais. Além disso, é importante citar que o método analítico baseado na técnica de eletroforese capilar com detecção condutométrica sem contato foi desenvolvido e otimizado durante o projeto de mestrado e tem grande relevância para este trabalho / Glycerol, 1,2,3-propanetriol, is the main by-product of biodiesel industry, around 10% w/w. Despite of several glycerol applications in industry, the offer of this polyalcohol has increased so much in the last years that it has accumulated in the mills, leading to an unbalance between its production and consumption. Thus, a lot of research has been done trying to use this abundant, cheap and non-toxic raw material as the basis for energy production and synthesis of other more value-added compounds. Among the several conversion processes, the electrooxidation has drawn attention due to its versatility, simplicity and low cost. Cyclic voltammetry is used for analyzing the electrochemical behavior of glycerol and the possible electroconversion products on several electrodes, as well as the influence of experimental variables, such as, solvent, supporting electrolyte and its concentration, substrate concentration on the electrocatalytic activity of the system. Capillary electrophoresis, coulometry and cyclic voltammetry were used for determination of rate conversion and quantitative analyses of glycerol and the obtained products through bulk electrolysis and how these parameters are influenced by experimental conditions. Besides, it is noteworthy that the analytical method based on capillary electrophoresis technique with contactless conductometric detection was developed and optimized along this Master project and it has large relevance for this work.
324

Synthèse des composés biologiquement actifs en utilisant des réactions photochimiques / Synthesis of biologically active compounds using photochemical reactions

Gomez fernandez, Mario Andres 09 January 2018 (has links)
En industrie chimique, on cherche continuellement des molécules biologiquement actives essentiellement pour les domaines pharmaceutique et agrochimique. De plus en plus les exigences à ces produits deviennent dures. Elles concernent, par exemple, les activités secondaires ou l'écotoxicité. En conséquence, un grand nombre de structures doit être testé pour trouver des composés actifs remplissant les propriétés imposées. En parallèle, les capacités dans l'industrie pour tester un grand nombre de composés différents en peu de temps ont considérablement augmentées. En conséquence, l'industrie cherche des nouvelles méthodes de synthèse pour accéder rapidement à une plus grande variété des structures moléculaires.Dans ce contexte, l'industrie chimique et pharmaceutique s'intéresse fortement aux réactions photochimiques appliquées en synthèse organique. Ces réactions permettent de synthétiser des composés en grande variété structurale inaccessibles par la synthèse organique conventionnelle. Les produits des réactions photochimiques sont une partie de l’espace chimique qui n’a pas encore été complètement exploré pour la recherche des structures avec de l’activité biologique.Dans les travaux de thèse presentés nous nous sommes interessés d’abord à la photocycloaddition [2+2] entre un groupement carbonyl et un alcène, la réaction de Paternò-Büchi. Nous avons utilisé cette reáction pour obtenir des oxétanes qui possèdent des groupements intéressants en agrochimie et au même temps des sites clés qui permettront d’autres transformations lors des étapes ultérieures. Par la suite nous avons exploré la réaction de Paternò-Büchi avec des alcènes fluorés. Les résultats ont été très encourageants. Nous avons découvert une nouvelle famille d’oxétanes fluorés très stables. Au vu de ses propriétés, ces produits peuvent être utilisés comme des <chassis moléculaires> pour l’obtention des composés biologiquement actifs. D’autre côté, une nouvelle reactivité photochimique a été découverte : il s’agit d’une réaction Photo-Wittig analogue. Cette reactivité chimique dépend des substituants sur le carbonyl. Nous pensons que cette réactivité chimique est directement liée à l’état excité du carbonyl. / In life sciences, there is a continuos research for new biological active molecules, this is true for both pharmaceultical industry and agrochemical industry. In the last years regulations have become more and more severe. In recent years, the technology for the test of new chemical compounds in industry has considerably evolved. Nowdays it is possible to test a vast number of compounds for the screening of biological activity in a short time. This means that industry is searching for new methodologies that allow the obtention of diverse chemical structures that can present biological activity.In this context, chemical industry, in particular, pharmaceutical and agrochemical industry are interested in the use of photochemical reactions in organic synthesis. Photochemical reactions allow the obtention of a variety of complex structures that are not easily obtained by classical methods. This chemical space has not been completly explored in the search of biological active compounds.In the works presented in this PhD research we first explored the [2+2] photocycloadtion of a carbonyl compound to an olefin, the called Paternò-Büchi reaction. We succesfully applied this reaction to obtain oxetanes wich posses agro-like substituents and key sites for further functionalization, a requirement demanded in industry. We also explored the use of fluorinated olefins in this photoreaction. The results are very promising: we discovered a new family of stable fluorinated oxetanes. These compounds can be used cas molecular scaffolds for the obtention of biological active compounds. At the same time, we discovered a new photochemical reactivity: a Photo-Wittig like reaction. This new reactivity depends on the substitution pattern of the carbonyl group. We hypothesize that the new reactivity depends on the excited state of the carbonyl compound.
325

Síntese, caracterização e estudo da reatividade de clusters de ouro / Synthesis, characterization and study of the reactivity of gold clusters

Sotelo, Adriana Fernandez 14 April 2004 (has links)
Nesta tese são abordadas as propriedades químicas e espectroscópicas dos clusters de Au-M, onde M = Pd ou Pt com o ligante PPh3. A nuclearidade destes compostos varia de 7: [Pd(PPh3)(AuPPh3)6](PF6)2 a 9: [Pt(AuPPh3)8](NO3)2 tendo ambos 16 e- de valência, segundo a contagem de elétrons estabelecida por Mingos. Um terceiro cluster preparado a partir dos precursores [pd(pPh3)(AuPPh3)6]2+ e Sn2+ também apresentou nuclearidade 9, com contagem de 16 e- de valência e possível fórmula molecular: [pd(SnCl3)2(AuPPh3)6](NO3)2. Foi empreendido um estudo da solubilidade e estabilidade do cluster [pd(SnCl3)2(AuPPh3)6](NO3)2 nos detergentes CTAB ou NaLS em meio aquoso, sendo esta solubilidade monitorada utilizando um espectrofotômetro UV/vis. A caracterização dos compostos foi feita com o uso das técnicas termogravimétricas (TGAlDTG) e espectroscópicas RMN, IV, UV-vis, Raman, FABMS e difração de raios-X. A estrutura cristalina e molecular do cluster [Pd(PPh3)(AuPPh3)6](PF6)2, obtida por difração de raios-X, mostra que o sistema cristalino é o triclínico com grupo espacial P1 com a = 17,138 (3) &#197;, b = 27,263 (5) &#197;, c = 27,543 (6) &#197;, &#945; = 101,70 (3) &#176;, &#946;= 105,80 (3) &#176;, &#947; = 90,19 (3) &#176;, T= 273°C, Z = 4, V= 12 102 &#197;3, R = 0,1149 e Rw = 0,2669 para 23 620 observações e radiação Mo K&#945;. Testes catalíticos realizados com o cluster [Pd(PPh3)(AuPPh3)6](NO3)2 na reação de hidrogenação, à alta pressão, do 1,5-COD foram bem sucedidos. / This work presents the chemistry and spectroscopic properties of phosphine-stabilized, M-centered Au cluster compounds where M = palladium or platinum. The nuclearity of the clusters ranges from 7: [Pd(PPh3)(AuPPh3) 6](PF6)2 to 9: [Pt(AuPPh3)8](NO3)2 both having 16-electrons in terms of the electron counting model established by Mingos. A third cluster prepared from [Pd(PPh3)(AnPPh3)6]2+ and Sn2r presents nuclearity 9 too and 16-electrons and the molecular formula apparently is [pd(SnCl3)2(AuPPh3)6](NO3)2. The solubility study of the cluster [pd(SnCl3)2(AuPPh3)6](NO3)2 was made using CTAB or NaLS and the results obtained are based on UV/vis analysis. Nuclear magnetic resonance (NMR), fast atom bombardment mass (FABMS), UV-visible, Infrared, TGA/DTG thermogravimetric and a single-crystal X-ray crystallographic analysis of the clusters were of great utility for the characterization of these compounds. The crystal data for [pd(pPh3)(AuPPh3)6 (PF6)2 are as follows: triclinic P1, a = 17,138 (3) &#197;, b = 27,263 (5) &#197;, c = 27,543 (6) &#197;, &#945; = 101,70 (3) &#176;, ¨&#946; = 105,80 (3) &#176;, &#947; = 90,19 (3) &#176;, T= 273°C, Z = 4, V= 12 102 &#197;3, R = 0,1149 and Rw = 0,2669 for 23 620 observed reflections and Mo K&#945; radiation. The catalytic application of the cluster [Pd(PPh3)(AuPPh3)6](NO3)2 in the hydrogenation of 1,5-COD brought promising results when the reaction is developed at high pressure.
326

Synthèse organique de macrocycles conjugués par réaction de Perkin / Formation of fully conjugated macrocycles by Perkin reactions

Robert, Antoine 19 December 2017 (has links)
La synthèse organique contrôlée de nanobagues de carbone est un challenge scientifique de longue date. Ces composés polycycliques aromatiques cylindriques peuvent être définis comme des sections de nanotubes de carbone plus larges qu’épaisses ; et la courbure de leur système pi pourrait leur conférer des propriétés électroniques intéressantes.Depuis quelques années, notre équipe développe une approche générale de synthèse de composés aromatiques polycycliques fonctionnalisés par des fonctions carboxyliques. Cette approche repose sur la réaction de Perkin entre des acides aryle-acétiques et des acides aryle-glyoxyliques, qui va permettre l’assemblage de ces briques élémentaires en longs précurseurs flexibles mais conjugués. Une dernière étape de cyclisation intramoléculaire, ou « graphitisation », pourra alors conjuguer complètement et donc rigidifier la molécule finale. Cette approche a permis la synthèse de plusieurs nouveaux composés aromatiques polycycliques linéaires.L’objectif de cette thèse est l’adaptation de l’approche de Perkin à la formation de nanobagues aromatiques. Un premier défi a été efficacement remporté avec l’obtention et la caractérisation complète de plusieurs macrocycles flexibles mais conjugués. Certains de ces macrocycles ont même été formés avec d’excellents rendements grâce à la mise en place d’une technique de haute dilution. Plusieurs tentatives de graphitisation ont été menées sur ces composés, impliquant différentes techniques de synthèse telles que la photochimie ou la catalyse au palladium, mais ne permirent malheureusement pas la formation des nanobagues aromatiques désirées. Néanmoins, en modifiant la structure initiale de certaines briques élémentaires nous avons pu obtenir d’autres macrocycles conjugués plus flexibles qui, après photocyclisation, ont abouti à la formation d’autres macrocycles conjugués présentant des structures rigides mais atypiques car non planes. / The controlled organic synthesis of carbon nanobelts has been scientific challenge for a long time. Such cylindrical polycyclic aromatic compounds can be defined as sections of carbon nanotubes that are larger than wide. Interesting electronic properties could result from the curvature of their pi system.These last years, our team has developed a general synthetic approach for the formation of carboxy-functionalised polycyclic aromatic compounds. This approach involves the Perkin reaction of arylacetic acids with arylglyoxylic acids, in order to form conjugated and flexible elongated precursors. The last step is an intramolecular cyclisation, or “graphitisation”, which rigidifies the precursor and yields a fully conjugated final molecule. Applying this approach, our team has synthesised several new linear polycyclic aromatic compounds.The aim of this thesis is to adapt the Perkin reaction for the formation of aromatic nanobelts. A first challenge has been solved by synthesising and fully characterising several flexible and conjugated macrocycles. Some of those macrocyclic compounds have been obtained with unexpectedly good yields using a high dilution addition technique. Graphitisations have been tried on some of those macrocycles by different synthetic methods, i.e. photochemistry and palladium catalysis, but none of them led to the formation of the desired aromatic nanobelt. However, by modifying the initial structure of some of the building blocks, we obtained more flexible conjugated macrocycles, which then reacted, by photocyclisation, to form conjugated and non-planar rigid macrocycles with atypical structures.
327

Análise da influência de condições experimentais sobre o comportamento eletroquímico e a distribuição dos produtos da oxidação eletroquímica de glicerol / Analysis of the influence of experimental conditions on electrochemical behavior and the distribution of products obtained by electrooxidation of glycerol

Wanderson Sirley Reis Teixeira 14 August 2015 (has links)
O glicerol, 1,2,3-propanotriol, é o principal subproduto da indústria do biodiesel, cerca de 10% em massa. Apesar das inúmeras aplicações que o glicerol tem na indústria, a oferta desse poliálcool, devido ao grande aumento da produção de biodiesel nos últimos anos, tem crescido tanto que o produto tem se acumulado nas usinas, levando a um desequilíbrio entre produção e consumo. Dessa forma, muita pesquisa vem sendo feita na tentativa de utilizar essa abundante, barata e não tóxica matéria prima como base para a obtenção de energia e outros produtos de maior valor agregado. Dentre os vários processos para a conversão do glicerol, a eletro-oxidação recebe atenção especial devido à sua versatilidade, simplicidade e baixo custo. Neste trabalho, utilizou-se a voltametria cíclica para a análise do comportamento eletroquímico do glicerol e dos possíveis produtos obtidos pela sua eletro-oxidação sobre diversos eletrodos e a influência de variáveis experimentais, tais como, solvente, eletrólito de suporte, concentrações de substrato e eletrólito de suporte, na atividade eletrocatalítica do sistema. As técnicas de eletroforese capilar, coulometria e voltametria cíclica foram utilizadas para a determinação da taxa de conversão e análise quantitativa do glicerol e dos produtos obtidos por meio de eletrólise exaustiva e como esses parâmetros são influenciados pelas variáveis experimentais. Além disso, é importante citar que o método analítico baseado na técnica de eletroforese capilar com detecção condutométrica sem contato foi desenvolvido e otimizado durante o projeto de mestrado e tem grande relevância para este trabalho / Glycerol, 1,2,3-propanetriol, is the main by-product of biodiesel industry, around 10% w/w. Despite of several glycerol applications in industry, the offer of this polyalcohol has increased so much in the last years that it has accumulated in the mills, leading to an unbalance between its production and consumption. Thus, a lot of research has been done trying to use this abundant, cheap and non-toxic raw material as the basis for energy production and synthesis of other more value-added compounds. Among the several conversion processes, the electrooxidation has drawn attention due to its versatility, simplicity and low cost. Cyclic voltammetry is used for analyzing the electrochemical behavior of glycerol and the possible electroconversion products on several electrodes, as well as the influence of experimental variables, such as, solvent, supporting electrolyte and its concentration, substrate concentration on the electrocatalytic activity of the system. Capillary electrophoresis, coulometry and cyclic voltammetry were used for determination of rate conversion and quantitative analyses of glycerol and the obtained products through bulk electrolysis and how these parameters are influenced by experimental conditions. Besides, it is noteworthy that the analytical method based on capillary electrophoresis technique with contactless conductometric detection was developed and optimized along this Master project and it has large relevance for this work.
328

Estudos da diastereosseletividade da adição de nucleófilos ao grupo carbonila de &#946;-cetossulfóxidos sulfanilados derivados da 1-indanona e 1-tetralona / On the diastereoselectivity of the addition of nucleophiles to 1- indanone and 1- tetralone sulfanylated &#946;-ketosulfoxides

Derisvaldo Rosa Paiva 17 June 2011 (has links)
Neste trabalho, foi proposta a preparação e redução, seguida de hidrólise oxidativa, de alguns derivados imínicos da 2-metilsulfinil-2-metilsufanil-1-tetralona e da 2-metilsulfinil-2-metilsulfanil-1-indanona. A 2-metilsulfinil-O-metil-oxima da 1-tetralona foi preparada pela oxidação da 2-metilsulfanil-O-metil-oxima. O sulfóxido assim obtido pôde ser sulfanilado empregando-se terc-butil lítio e metanotiolsulfonato de metila, resultando um único diastereoisômero que se mostrou inerte na reação de redução da função imínica com NaBH4. Tentativas de preparar a N-tosil-imina da 2-metilsulfinil-1-tetralona, por oxidação do sulfeto correspondente, não conduziram ao produto esperado, mas sim à enamina. Buscando uma rota alternativa para a preparação de derivados imínicos de sulfinil ciclanonas sulfaniladas, foram preparados &#946;-cetossulfóxidos derivados da 1-tetralona e da 1-indanona que, após serem sulfanilados, seriam submetidos às reações com aminas aromáticas ou alifáticas. As reações de sulfanilação da 2-metilsulfinil-1-indanona e da 2-metilsulfinil-1-tetralona foram efetuadas em condições de transferência de fase, na presença dos catalisadores TEBAC ou QUIBEC. Para ambos os casos, os rendimentos de produto foram cerca de 80 %. Enquanto os dois catalisadores conduziram a resultados estereoquímicos similares para a sulfanilação da 2-metilsulfinil-1-indanona, para a 2-metilsulfinil-1-tetralona, o uso do catalisador quiral QUIBEC resultou em um aumento da diastereosseletividade da reação, no sentido da formação do diastereoisômero majoritário de configuração relativa CR,SR. Foram também efetuadas as reações de sulfanilação das duas 2-metilsulfinil ciclanonas em meio homogêneo, empregando como bases o hidróxido de lítio ou o di-isopropil amideto de magnésio. Porém, as reações das sulfinil ciclanonas sulfaniladas assim preparadas com a anilina e com a metil-amina não foram bem sucedidas. As reações de redução com boroidreto de sódio das duas sulfinil ciclanonas sulfaniladas conduziram aos respectivos álcoois em cerca de 70 % de rendimento e na forma de um único diastereoisômero, de configuração relativa SR,C-1R,C-2R, no caso do tetralol. As duas metilsulfinil ciclanonas sulfaniladas, opticamente ativas, foram preparadas em bons rendimentos, mas sob forma escalêmica, o que não permitiu o prosseguimento do estudo do curso estereoquímico da redução da carbonila de tais compostos. A reação de adição do enolato de lítio do acetato de etila à 2-metilsulfinil-2-metilsulfanil-1-indanona conduziu ao produto esperado em bom rendimento, mas com baixo excesso diastereoisomérico. Em condições análogas, a 2-metilsulfinil-2-metilsulfanil-1-tetralona mostrou-se inerte. / The original proposal of this research work was to prepare imines of 2-methylsulfinyl-2-methylsulfanyl-1-tetralone and 2-methylsulfinyl-2-methylsulfanyl-1-indanone that would be subsequently reduced and submitted to oxidative hydrolysis. By oxidation of 2-methylsulfanyl-1-tetralone-O-methyloxime the corresponding sulfoxide could be prepared, and submitted to the sulfanylation reaction using tert-butyllittium/methyl methanethiolsulfonate. The resulting product was obtained as a single diastereoisomer but showed to be unreactive towards reduction using sodium borohydride In attempting to convert the 2-methylsulfanyl-1-tetralone into the corresponding sulfoxide by oxidation, the corresponding sulfinylenamine was obtained instead of the expected sulfinylimine. Searching for an alternative synthetic route to the desired imines, the required &#946;-ketosulfoxides were prepared and sulfanylated under phase-transfer catalysis using TEBAC or QUIBEC, as catalysts. In both cases, product yield was ca. 80%. Although for the sulfanylation of 2-methylsulfinyl-1-indanone using either TEBAC or QUIBEC the same diastereoselectivity was observed, for the reaction performed with 2-methylsulfinyl-1-tetralone and QUIBEC an improved diastereoselectivity was observed, in favour of the CR,SR diastereoisomer. Analogous sulfanylation reactions were performed in homogeneous medium in the presence of lithium hydroxide or magnesium diisopropylamide acting as bases. However, the reactions of the prepared 2-metylsulfinyl-2-methylsulfanyl ciclanones with aniline or methylamine were unsuccessful. The borohydride reduction of the 2-metylsulfinyl-2-methylsulfanyl ciclanones afforded the corresponding diastereoisomerically pure alcohols in ca. 70% yield, bearing, in the case of the tetralol derivative, the SR,C-1R,C-2R relative configuration. The two optically active sulfanylated 2-methylsulfinyl ciclanones could be prepared in good yields but as a scalemic mixture that precluded further studies in order to determine the stereochemical course of the carbonyl reduction. As for the addition reaction of the ethyl acetate lithium enolate to 2-methylsulfinyl-2-methylsulfanyl-1-indanone, the expected adduct was obtained in good yield but with poor diastereoselectivity. Under the same experimental conditions, the 2-methylsulfinyl-2-methylsulfanyl-1-tetralone underwent no reaction.
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Benzo[5]radialenos como precursores de fluorenos e benzo[b]fluorenos / Benzo[5]radialenes as precursors of fluorenes and benzo[b]fluorenes

Andreas Albert Von Richthofen 03 July 2015 (has links)
Neste trabalho demonstramos a preparação de fluorenos e benzo[b]fluorenos por uma nova rota sintética, baseada na reação de Diels-Alder de derivados benzo[5]radialênicos. Para a preparação destes últimos investigamos diversas estratégias, partindo de p-benzoquinona e três dienos: 1,1-dimetoxiciclopentadieno, 6,6-dimetilfulveno e 6-acetoxifulveno. A partir de cada fulveno obtivemos um benzo[5]radialeno diferente, sendo que o derivado dimetilado se mostrou inerte como dieno em cicloadições. O benzo[5]radialeno derivado do 6-acetoxifulveno, reagiu com diversos dienófilos tais como p-benzoquinona, 2,3-dicloro-p-benzoquinona, 1,4-naftoquinona, N-metilmaleimida, acetilenodicarboxilato de dimetila, acrilato de metila, etc. Notamos uma alta quimiosseletividade entre os sistemas diênicos, pois obtivemos apenas adutos trans. Com alguns dienófilos observamos a formação de compostos aromatizados (formados pela eliminação de ácido acético que, para os casos pertinentes, foi regiosseletiva). Com dienófilos como acrilato de metila ou sulfinil-naftoquinonas, alta regiosseletividade foi observada. Tentamos explorar tais seletividades para a preparação de análogos da eucapsitriona. Os adutos de Diels-Alder obtidos constituem exemplos de derivados fluorênicos e benzo[b]fluorênicos que, ultimamente, têm recebido grande atenção tanto por aspectos estruturais como por apresentarem propriedades biológicas importantes / In this work we demonstrated the preparation of fluorenes and benzo[b]fluorenes by a new synthetic route, based on the Diels-Alder reaction of benzo[5]radialenes derivatives. For the preparation of the last we investigated several strategies starting from p-benzoquinone and three dienes: 1,1-dimethoxycyclopentadiene, 6,6-dimethylfulvene and 6-acetoxyfulvene. From each fulvene we obtained a different benzo[5]radialene, but the dimethylated one showed no reactivity in cycloadditions. The benzo[5]radialene prepared from 6-acetoxyfulvene reacted with several dienophiles such as p-benzoquinone, 2,3-dichloro-p-benzoquinone, 1,4-naphtoquinone, N-methylmaleimide, dimethyl acetylenedicarboxylate, methyl acrylate, etc. We noted a high quimiosselectivity between the dienic sub units since only trans adducts were obtained. With some dienophiles we observed the formation of aromatized compounds (formed by acetic acid elimination which, for suitable cases, was regiosselective). With dienophiles such as methyl acrylate or sulfinyl-naphtoquinones high regiosselectivity was observed. We tried to explore such selectivities to prepare eucapsitrione analogues. These Diels-Alder adducts are examples of fluorenic and benzo[b]fluorenic derivatives, compounds that have gained considerable attention due to structural and biological aspects.
330

Développements de méthodologies de synthèse innovantes pour l'obtention de chimiothèques de polyélectrolytes multifonctionnalisés / Development of innovative synthetic methodologies for the design of multifunctional polyelectrolyte libraries

Benlahouès, Antoine 17 December 2018 (has links)
Les polyélectrolytes sont des polymères chargés, solubles dans l'eau, omniprésents dans les nature et capables d’interagir avec de nombreux composants cellulaires. Leur utilisation dans des essais cliniques est actuellement limitée par le manque de données fiables sur les relations entre leurs structures et leurs biopropriétés. Ce projet s'inscrit dans un programme plus vaste visant à obtenir une bibliothèque de polyélectrolytes multifonctionnalisés bien caractérisés pour le criblage de biopropriétés. Dans ce cadre, nous avons cherché à synthétiser des chaînes macromoléculaires contenant des unités maloniques C(COOH)2 situées à différentes positions le long du squelette du polymère. Ces unités peuvent être utilisées comme points de départ pour introduire plusieurs autres groupes fonctionnels en utilisant de nombreuses réactions de la chimie organique, conduisant à un grand nombre de structures à partir d'un squelette commun, y compris des copolymères. Cette thèse est schématiquement divisée en quatre parties : (a) une présentation bibliographique des relations existant entre structures et propriétés pour des polymères multifonctionnalisés, suivie d'une analyse plus spécifique de l'importance du positionnement d’esters carboxyliques le long d’une chaîne carbonée, (b) une description des efforts expérimentaux menés pour obtenir les poly(triméthylène-1,1-dicarboxylate)s, des intermédiaires clés dans la synthèse des polymères décrits dans les chapitres suivants, (c) une description de l'hydrolyse du précurseur ci-dessus, donnant l'acide poly(triméthylène-1,1-dicarboxylique), ainsi que des propriétés et de la réactivité de ce polyacide, (d) un rapport détaillé sur la synthèse de l’acide poly(triméthylène carboxylique) par décarboxylation quantitative du polyacide ci-dessus, ainsi que sur les propriétés et réactivité de ce polyacide. Dans les deux dernières sections, un accent particulier est mis sur la portée et les limites de diverses procédures de post-fonctionnalisation lorsque l'on tente d'obtenir une bibliothèque de polymères fonctionnels à partir de précurseurs polycarboxyliques / Polyelectrolytes are water-soluble charged polymers that are ubiquitous in life science and capable of interacting with many cellular constituents. Their use in clinical trials is currently limited by a lack of reliable data on the relationships linking their structures to bioproperties. This project is part of a larger program aimed at obtaining a library of well-characterized multifunctionalized polyelectrolytes for the screening of bioproperties. In this framework, we aimed at synthesizing macromolecular chains containing malonic units C(COOH)2 located at various positions alongside the polymer backbone. These units can be used as starting points to introduce several other functional groups using many reactions from organic chemistry, leading to a great number of structures from a common skeleton, including copolymers. This thesis is schematically divided into four parts: (a) a bibliographical presentation of the relationships existing between structures and properties for multifunctional polymers, followed by a more specific analysis on the importance of carboxylic esters positioning alongside a carbon chain backbone, (b) a description of experimental efforts aimed at obtaining poly(trimethylene-1,1-dicarboxylate)s, key intermediates in the synthesis of a large family of polymers described in the next chapters, (c) a depiction of the hydrolysis of the above precursor, yielding poly(trimethylene-1,1-dicarboxylic acid), as well as of the properties and reactivity of this polyacid, (d) a detailed report on the synthesis of poly(trimethylenecarboxylic acid) via the quantitative decarboxylation of the above polyacid, as well as of the properties and reactivity of this polyacid. A special focus is made in the last two sections on the scope and limitations of various post-functionalizing procedures when attempting to obtain a large library of functional polymers from polycarboxylic precursors

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