Στην παρούσα διατριβή ειδίκευσης παρασκευάσθηκαν νανοσύνθετα υλικά αργιλικών ορυκτών/διοξειδίου του τιτανίου (TiO2) για την περιγραφή και μελέτη των νέων βελτιωμένων χαρακτηριστικών τους και την εφαρμογή τους σαν φωτοκαταλύτες στη διάσπαση ανόργανων αέριων ρύπων οξειδίων του αζώτου (NOX). Τρία αργιλικά ορυκτά (σαπωνίτης, παλυγορσκίτης και αλλοϋσίτης) χρησιμοποιήθηκαν για την διεξαγωγή των πειραμάτων. Δείγματα σαπωνίτη και παλυγορσκίτη συλλέχθηκαν από τη λεκάνη του Βεντζίου στα Γρεβενά και αλλοϋσίτη από τη νήσο Λήμνο. Δύο διαφορετικές μορφές νανοσύνθετων αργιλικού ορυκτού/TiO2 παρήχθησαν με δύο διαφορετικές μεθόδους και χρησιμοποιήθηκαν για τη μελέτη της φωτοαποικοδόμησης ανόργανων αέριων ρύπων NOX : Υποστυλωμένα με TiO2 νανοσύνθετα σαπωνίτη (Ti-sap1, Ti-sap2) παρήχθησαν με τη μέθοδο της «solvothermal synthesis” χρησιμοποιώντας TiCl3 σαν πρόδρομο TiO2 και νανοσύνθετα TiO2/ παλυγορσκίτη (Ti-pal) και TiO2/ αλλοϋσίτη (Ti-hall) παρήχθησαν με τη μέθοδο κολλοειδούς διαλύματος σε πήκτωμα (sol-gel) χρησιμοποιώντας Titanium Tetraisopropoxide (Ti(OC3H7)4) σαν διάλυμα διασποράς-επικάθησης. Για τον χαρακτηρισμό των ιδιοτήτων των φυσικών και τροποποιημένων δειγμάτων εφαρμόστηκαν διαφορετικές τεχνικές (XRD, FTIR-ATR, SEM-EDS, TEM, DLS, BET, porosimetry). Τα νανοσύνθετα αποδείχθηκαν αρκετά αποτελεσματικά για τη φωτοδιάσπαση των αέριων ρύπων NOX συγκριτικά με τον standard τύπο διοξειδίου του τιτανίου, Degussa P25, που χρησιμοποιείται γιαυτό το σκοπό. Tα υποστυλωμένα νανοσύνθετα Ti-sap1 και Ti-sap2 (με αναλογίες μάζας TiO2:σαπωνίτη = 0.2:1 και 0.1:1 αντίστοιχα) έδειξαν αύξηση της ειδικής τους επιφάνειας συγκριτικά με το φυσικό δείγμα σαπωνίτη και μεσοπορώδη δομή με κατανομή πόρων 5.7-9.8nm για το Ti-sap1 και 3.8nm για το Ti-sap2. Και τα δύο νανοσύνθετα απέκτησαν αυξημένη φωτοκαταλυτική ικανότητα βάση του περιεχόμενου ποσοστού TiO2 συγκριτικά με τον standard P25 λόγω της ομοιογενούς διασποράς των σωματιδίων TiO2 στον σαπωνίτη αλλά συγκρίνοντας τα δύο δείγματα Tisap1 και Tisap2, το Tisap2 είχε καλύτερη φωτοκαταλυτική δράση από το Tisap1. Όσον αφορά τα νανοσύνθετα TiO2-pal και TiO2-hall τα αποτελέσματα έδειξαν τη δημιουργία μεσοπορώδους δομής με πόρους 6.5 και 5.6 nm αντίστοιχα για το κάθε υλικό ενώ η μακροπορώδης δομή (lumen) του αλλοϋσίτη δεν υπήρχε στο τροποποιημένο δείγμα λόγω του ότι καλύφθηκε από τα νανοσωματίδια του TiO2 με αποτέλεσμα να προκύψει ένα υλικό με μικρότερο μέγεθος πόρων. Τα δύο δείγματα έδειξαν υψηλή φωτοκαταλυτική ικανότητα στη διάσπαση των αέριων ρύπων NOX υπό την επίδραση ορατής (λ>510nm) και υπεριώδους (λ>290nm) ακτινοβολίας σε σύγκριση με τα αποτελέσματα που έδωσε ο standard τύπος TiO2 P25. / In this thesis TiO2/clay nanocomposites have been synthesized and characterized as photocatalysts in the decomposition of NOx gases. Three different clay minerals (saponite, palygorskite and halloysite) have been used. The saponite and palygorskite samples were collected from Western Macedonia (Grevena, Ventzia basin) and halloysite from Lemnos island. The two different forms of nanocomposites that synthesized by two different methods were: TiO2 -pillared saponite (Ti-sap1, Tisap2) were successfully prepared by solvothermal synthesis using titanium trichloride as the precursor and TiO2- Palygorskite (Ti-pal) and TiO2-Halloysite (Ti-hall) nanocomposites were prepared by deposition of anatase form of TiO2 on the clay surfaces using a sol–gel method with titanium isopropoxide as a precursor. The characterization of the natural and modified samples was done by using different techniques (XRD, FTIR-ATR, SEMEDS, TEM, DLS, BET, porosimetry) The photocatalytic properties of the TiO2-clay nanocomposites were found to be better than that of the standard titania, Degussa P25 in decomposing NOX gases. The pillared TiO2 nanocomposites Ti-sap1, Tisap2 (mass ratio of TiO2:saponite= 0.2:1 and 01:1 respectively) showed a mesoporous structure compared to the natural saponite, with the distribution of pore diameters centered at 5.7-9.8 and at 3.8 nm, with high specific surface areas. Both TiO2-saponite nanocomposites showed higher photocatlytic activity than the standard (Degussa P25) based on TiO2 content because the TiO2 was well dispersed on saponite. By comparing the two modified samples Ti-sap1, Ti-sap2, the second one showed better photocatalytic activity than Ti-sap1 The results of the other two nanocomposites, Ti-hall and Ti-pal, showed mesopores of about 5.6 and 6.5 nm, respectively, while the macropores of halloysite (lumen) disappeared. The latter is attributed to the covering of the lumen of halloysite tubes by TiO2 nanoparticles and for that reason the pore size of the TiO2–treated halloysite was significantly smaller. The clay minerals- TiO2 samples showed significantly higher activity in decomposing NOx gas under visible-light irradiation (λ> 510 nm) and UV light irradiation (λ> 290 nm) compared to that of the standard commercial TiO2, P 25.

No description available.

The current economic system began in the mid-twentieth century to present unsustainability signals due to the realization of various externalities that go beyond the destruction and depletion of natural resources. In this scenario, the chemical-industrial activity due to its polluting action and some world level disaster is being questioned and required a new attitude towards the issues surrounding the care and preservation of the environment. In this context, this thesis aimed to investigate how environmental issues - Environmental Problems, Green Chemistry, Sustainable Development and Environmental Education - are being inserted in the course of degree in Chemistry offered by the Federal University of Sergipe on the campus of São Cristóvão. To this end, we sought to identify the concepts, methods and practices adopted by teachers. The Qualitative Research and interpretive served as the theoretical north in order to analyze in depth the research universe. In data collection were used: Documents and interviews analysis of semi-structured screen in the course teachers. In the analysis of the results there have based on the Textual Analysis Discourse. In order to meet the rigors and the internal validity of the research, the triangulation method was used so that the inferences and interpretations of the results guarantee the quality of the research. The diagnosis of curricular analysis was carried out by reference to the criteria proposed by the network Environmentalisation Curricular for Advanced Studies, pointing to an innovative curriculum that seeks to meet the legal requirements, but when broken down into its curriculum components, we see a low structure flexible where environmental issues are poorly covered. Regarding the analysis categories investigated, it is observed by teachers that treatment of environmental problems is limited to the development of their laboratory activities, micro context. An understanding of sustainable development that is widely criticized. And behaviorists views on environmental education. Generally that appear as anthropocentric conceptions, based on a technical-instrumental rationality, where technical solutions are sufficient to enable the current problems. Regarding the Green Chemistry, there are certain ignorance associated with its principles and philosophy, and their ideas framed in the developmental chain or pragmatic macro trend. The data collected both in research as in the references point out that the way they operated, the Green Chemistry is a rationalization instrument that could end up collaborating in maintaining the interests of hegemonic groups. As for the methods and practices have been reported the use of pedagogical interventions that encourage participation and the construction of knowledge by the students, however, is still marked concern about the transmission of disciplinary scientific content. / El sistema económico actual se inició a mediados del siglo XX para presentar señales insostenibilidad debido a la realización de diversas externalidades que van más allá de la destrucción y el agotamiento de los recursos naturales. En este escenario, la actividad química industrial debido a su acción contaminante y algún desastre nivel mundial está siendo cuestionado y requiere una nueva actitud hacia los temas relacionados con el cuidado y la preservación del medio ambiente. En este contexto, esta tesis como objetivo investigar cómo medioambiental temas - Problemas Ambientales, Química Verde, Desarrollo Sostenible y Educación Ambiental - están siendo insertados en el Grado en Química ofrecido por la Universidad Federal de Sergipe en el campus de São Cristóvão. Con este fin, hemos tratado de identificar los conceptos, métodos y prácticas adoptadas por los profesores.La investigación y la interpretación cualitativa sirvieron de norte teórico con el fin de analizar en profundidad el universo de la investigación. En la recolección de datos se utilizaron: Documentos y entrevistas análisis de pantalla semi-estructurado de los profesores del curso. En el análisis de los resultados se han basado en el Análisis de Pruebas Discurso. Con el fin de cumplir con los rigores y la validez interna de la investigación, se utilizó el método de triangulación para que las inferencias e interpretaciones de los resultados avalan la calidad de la investigación. El diagnóstico de análisis curricular se llevó a cabo en función de los criterios propuestos por el Currículo ambientalización red de Estudios Avanzados, que apunta a un plan de estudios innovador que busca cumplir con los requisitos legales, pero cuando se desglosa en sus componentes curriculares, vemos una estructura de bajo donde las cuestiones ambientales flexibles están mal cubiertos. En cuanto a las categorías de análisis investigados, se observa por los profesores que el tratamiento de los problemas ambientales se limita al desarrollo de sus actividades de laboratorio, micro contexto. La comprensión del desarrollo sostenible que es ampliamente criticado. Y conductistas puntos de vista sobre la educación ambiental. En general que aparecerá como concepciones antropocéntricas, con base en una racionalidad técnico-instrumental, donde las soluciones técnicas son suficientes para permitir a los problemas actuales. En cuanto a la Química Verde, hay cierto desconocimiento asociados con sus principios y la filosofía, y sus ideas enmarcadas en la cadena de desarrollo o pragmática tendencia macro. Los datos recogidos tanto en la investigación como en las referencias señalan que la forma en que operan, la Química Verde es un instrumento de racionalización que podría terminar colaborar en el mantenimiento de los intereses de los grupos hegemónicos. En cuanto a los métodos y prácticas se han reportado el uso de intervenciones pedagógicas que fomenten la participación y la construcción del conocimiento por los estudiantes, sin embargo, sigue siendo marcada preocupación por la transmisión de contenidos científicos disciplinaria. / O sistema econômico vigente começou, em meados do século XX, a apresentar sinais de insustentabilidade por conta da constatação de diversas externalidades, que ultrapassam a destruição e o esgotamento dos recursos naturais. Nesse cenário, a atividade químico-industrial, devido à sua ação poluidora e alguns desastres de repercussão mundial, passa a ser questionada e exigida uma nova postura frente às questões que envolvem o cuidado e a preservação do meio ambiente. Nesse contexto, esta Tese teve por objetivo investigar como as questões ambientais – Problemas Ambientais, Química Verde, Desenvolvimento Sustentável e Educação Ambiental– estão sendo inseridas no curso de Licenciatura em Química oferecido pela Universidade Federal de Sergipe no campus de São Cristóvão. Para tal, buscou-se conhecer as concepções, métodos e práticas adotadas pelos professores. A Pesquisa Qualitativa e interpretativa serviu de norte teórico no intuito de analisar em profundidade o universo pesquisado. Na coleta de dados foram utilizados: Análise de Documentos e Entrevistas semiestruturadas com os docentes do curso em tela. Na análise dos resultados, têm-se como base a Análise Textual Discursiva. Com vistas a atender os rigores e à validade interna da pesquisa, o método de triangulação foi utilizado a fim de que as inferências e interpretações dos resultados garantissem a qualidade da investigação empreendida. O diagnóstico da análise curricular foi realizado tomando como referência os critérios propostos pela rede de Ambientalização Curricular de Estudos Superiores, apontando para um currículo inovador, que procura atender às exigências legais, porém quando se desdobram em suas componentes curriculares, vê-se uma estrutura pouco flexível, em que as questões ambientais são pouco contempladas. Em relação às categorias de análise investigadas, observa-se, por parte dos professores, que o tratamento dos problemas ambientais está limitado ao desenvolvimento de suas atividades laboratoriais, contexto micro. Um entendimento de desenvolvimento sustentável que é bastante criticado. E visões comportamentalistas sobre Educação Ambiental que, de modo geral, apresentam-se como concepções antropocêntricas, fundadas em uma racionalidade técnico-instrumental, onde soluções técnicas são suficientes para viabilizar os problemas atuais. Em relação à Química Verde, há certo desconhecimento associado com seus princípios e sua filosofia, sendo suas ideias enquadradas numa corrente desenvolvimentista ou na macrotendência pragmática. Os dados levantados tanto na pesquisa, quanto nas referências apontam que, do modo como é operada, a Química Verde representa um instrumento de racionalização, que pode acabar colaborando na manutenção dos interesses de grupos hegemônicos. Quanto aos métodos e práticas, foram relatadas a utilização de intervenções pedagógicas que estimulam a participação e a construção do conhecimento por parte dos discentes, porém, ainda é marcante a preocupação com a transmissão dos conteúdos científicos disciplinares.

No presente trabalho foram investigados vários sistemas moleculares contendo o dióxido de enxofre (SO2) como espécie elétron aceptora e diversas espécies elétron doadoras como aminas (alifáticas e aromáticas), complexos inorgânicos e líquidos iônicos. Estes compostos são chamados de complexos do tipo doador-aceptor, que no caso do SO2 são caracterizados por apresentarem baixas energias de ligação entre as espécies se comparada à maioria dos complexos desta categoria. A caracterização vibracional dos complexos e adutos de SO2, assim como do processo de transferência de carga (CT) intermolecular e da estabilidade destes sistemas consistem nos principais objetivos deste trabalho, tendo sido para tanto utilizadas as técnicas de espectroscopia eletrônica (UV-Vis), espectroscopia vibracional (Raman e infravermelho), cálculos de química quântica (DFT) e cálculos de dinâmica molecular clássica (MD). No caso de complexos entre aminas e SO2 foi observado que além da basicidade das aminas, o efeito estérico consiste em um fator crucial para a estabilidade. No caso de aminas aromáticas, complexos coloridos foram formados permitindo a obtenção de espectros Raman ressonante. No caso de um complexo inorgânico, com utilidade potencial como sensor de SO2foi observada a aplicação da espectroscopia Raman ressonante na caracterização do complexo de estequiometria 2:1. Já no caso da interação de SO2 e líquidos iônicos (LI) foi observada a capacidade de absorção de SO2 por LI e a conseqüente mudança das propriedades físico-químicas destes líquidos, o que abre a possibilidade, além de sua potencial utilização no contexto ambiental, de sintonizar propriedades de líquidos iônicos através da adição controlada de SO2. / In the present work molecular systems bearing the sulfur dioxide (SO2) as an electron acceptor species and several electron donor species as amines (aliphatic and aromatic), inorganic complexes and ionic liquids were investigated. Such complexes are commonly known as donor-acceptor complexes, and in particular, in the case of SO2 complexes are characterized by low binding energies when compared with the majority of charge transfer (CT) complexes. The vibrational characterization of the SO2 complexes, as well as of the intermolecular charge transfer (CT) process and of their stabilities are the main subjects of this work, and for such, electronic spectroscopy (UV-Vis), vibrational spectroscopy (Raman and infrared), quantum chemical (DFT) calculations and molecular dynamics (MD) simulations were used. In the case of complexes formed by amines and SO2 it was observed that besides the amine basicities, the steric effect plays a crucial role in their stabilities. In the case of aromatic amines, colored complexes were formed allowing the resonance Raman study. The use of Raman spectroscopy in the characterization of an inorganic complex (SO2 sensor) indicates the potential use of the resonance Raman effect for SO2 monitoring. In the case of the interaction between SO2 and ionic liquids it was observed the great capability of ionic liquids as SO2 absorbers, and the consequent change in the physical-chemical properties of these liquids, what opens the possibility, in addition to its potential use in the environmental context, for tuning the ionic liquids properties via the controlled addition of SO2.

Submitted by Marilene Donadel (marilene.donadel@unioeste.br) on 2018-11-13T19:40:32Z No. of bitstreams: 1 Alexandra_Amaral_2018.pdf: 6685905 bytes, checksum: ec13a764da46630f5757867d952330fd (MD5) / Made available in DSpace on 2018-11-13T19:40:33Z (GMT). No. of bitstreams: 1 Alexandra_Amaral_2018.pdf: 6685905 bytes, checksum: ec13a764da46630f5757867d952330fd (MD5) Previous issue date: 2018-07-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / It is notable that with technological advances and scientific research, organic synthesis has provided the synthesis of several compounds that are essential to meet the needs of mankind. 3-Indolyl-glycine derivatives have been the subject of several studies, since they are precursors of non-proteinogenic amino acids that act as synthetic intermediates of compounds with important biological activity. However, the synthetic routes described in the literature for these compounds present disadvantages, since they use organic solvents, extreme temperatures, non-recoverable catalysts and long reaction periods. Thus, the search for the development of alternative methodologies has attracted great attention in Organic Synthesis in order to reduce environmental impact, reduce process costs and minimize waste formation. In view of this scenario, the proposal of a new methodology for the synthesis of 3-indolyl glycine derivatives, via a multi-component reaction (Aza-Friedel-Crafts) between indoles, ethylglyoxalate and anilines, which follow the principles established by Green Chemistry, are somewhat of great interest to be studied. After a systematic study of the reaction conditions, two synthetic methodologies were established. In the first methodology a catalyst and surfactant was used in the reaction, under ambient temperature, however this condition led to the formation of by-product from the rearrangement of the desired product. In addition, the catalytic system of this synthetic methodology presented potential to be recycled, but its (re) use showed a decrease in yields, and it is not feasible to use this methodology. Thus, another synthetic methodology was proposed, in which only surfactant was used without the use of the catalyst, with heating of 50 ºC. The second methodology was more feasible, since the yields of the products obtained with the variation of the indole substrate were excellent. The synthesized compounds were evaluated for their biological activity. Bioassays of phytotoxic activity on lettuce seeds (Lactuca sativa) were carried out, in which it was verified that these compounds interfere in seed germination and root growth. Compounds 4b, 4j and 4n showed remarkable germination inhibitory activity at the concentration of 25 ppm. In inhibition of growth, compounds 4a, 4l and 4n showed inhibitory activity already at concentrations of 10 ppm. Such compounds were as active as the glyphosate and atrazine herbicides tested. It is emphasized that compound 4n had inhibitory activity both for germination and for growth of the species studied. Thus, the compounds presented in this paper provide an experimental basis for future studies on pesticides based on 3-Indolyl-glycine derivatives, since it has potential applications for herbicidal activity. / É notório que com os avanços tecnológicos e com as pesquisas científicas, a síntese orgânica proporcionou a síntese de diversos compostos que são essenciais para suprir as necessidades da humanidade. Os compostos derivados de 3-Indolil-glicina tem sido alvo de diversos estudos, visto que são precursores de aminoácidos não proteinogênicos que atuam como intermediários sintéticos de compostos com importante atividade biológica. Entretanto, as rotas sintéticas descritas na literatura para estes compostos apresentam desvantagens, visto que as mesmas utilizam solventes orgânicos, temperaturas extremas, catalisadores não recuperáveis e longos períodos de reação. Desse modo, a busca pelo desenvolvimento de metodologias alternativas tem atraído grande atenção na Síntese Orgânica de modo a proporcionar a redução do impacto ambiental, reduzir custos do processo e minimizar a formação de resíduos. Diante desse cenário, a proposta de uma nova metodologia para a síntese de derivados de 3-indolil-glicina, via reação multicomponente (Aza-Friedel-Crafts) entre indóis, etilglioxalato e anilinas, que contemplam os princípios estabelecidos pela Química Verde, são algo de grande interesse a ser estudado. Após um estudo sistemático das condições de reacão, estabeleceram-se duas metodologias sintéticas. Na primeira metodologia foi utilizado um catalisador e surfactante na reação, sob temperatura ambiente, entretanto essa condição levou a formação de subproduto oriundo do rearranjo do produto desejado. Além disso, o sistema catalítico dessa metodologia sintética apresentou potencial de ser reciclado, porém sua (re)utilização demonstrou um decréscimo nos rendimentos, não sendo viável o uso dessa metodologia. Desse modo foi proposta outra metodologia sintética, na qual só foi utilizado surfactante sem o uso do catalisador, com aquecimento de 50 ºC. A segunda metodologia se mostrou mais viável, visto que os rendimentos dos produtos obtidos com a variação do substrato indólico foram excelentes. Os compostos sintetizados foram avaliados quanto à sua atividade biológica. Bioensaios de atividade fitotóxica em sementes de alface (Lactuca sativa) foram realizados, nos quais se verificou que estes compostos interferem na germinação das sementes e no crescimento das radículas. Os compostos 4b, 4j e 4n mostraram notável atividade inibitória de germinação na concentração de 25 ppm. Na inibição do crescimento, os compostos 4a, 4l e 4n apresentaram atividade inibitória já nas concentrações de 10 ppm. Tais compostos foram tão ativos quanto os herbicidas glifosato e atrazina testados. Salienta-se que o composto 4n teve atividade inibitória tanto para a germinação quanto para o crescimento da espécie estudada. Desse modo, os compostos apresentados neste trabalho fornecem uma base experimental para futuros estudos sobre pesticidas à base dos derivados de 3-Indolil-glicina, visto que tem aplicações potenciais para atividade herbicida.

This thesis entitled “Organic Transformations in Water: Synthetic and Mechanistic Studies towards Green Methodologies” is in two parts. Part-I describes various synthetic studies aimed at developing improved methodologies; Part-II describes certain mechanistic studies directed towards an improved understanding of phase transfer catalysis and the hydrophobic effect. Water is uniquely advantageous as a solvent. It is environmentally benign, non-flammable, liquid over a wide temperature range and possesses a high heat capacity that makes it inherently safe. Water also catalyses chemical transformations between insoluble organic reactants. Water thus serves as a reaction medium, a product partitioner and a reaction catalyst.1 Part-I:- Reactions in Water under both Microwave and Ambient Conditions Part-I is further divided into three chapters. Chapter II deals with reactions of 2-nitroalcohols (2NAs), and is divided into three sections. Section A describes the synthesis of nitroalkanes via the microwave-assisted, water-mediated chemoselective reduction of 2NAs using tributyltin hydride (Bu Scheme 1 ). The 2NAs, synthesized from nitromethane and aldehydes (aliphatic, alicyclic, heterocyclic or m- & p-substituted aromatic aldehydes), were converted into corresponding nitroalkanes in excellent yields. The 2NAs derived either from substituted nitromethane [nitroethane, (nitromethyl)benzene, etc.] or bulky aldehydes (o-substituted aromatic aldehydes), however, failed to furnish nitroalkanes under these conditions. Also a major solvent effect was observed: the extent of conversion was greater in water than in water-polar 3SnH) as reducing agent. The chemoselective reduction of 2NAs to nitroalkanes was observed accidentally while trying to remove the nitro group of 2NAs in a Bu3SnH-AIBN-water system under microwave conditions. When equimolar quantities of 2NA and Bu3SnH were added to water, microwave irradiation led to nitroalkanes (protic solvent mixtures and the reaction did not occur either in aprotic polar or non-polar solvents. Scheme 1. Microwave assisted chemoselective reduction of 2NAs to nitroalkanes in Bu3SnH-water In Section B, the microwave assisted synthesis of nitroalkanes from nitroalkenes has been described. Equimolar quantities of nitroalkene and Bu Scheme 2 ). The nitroalkenes substituted even by bulky groups at C-1 & C-2 were converted into corresponding nitroalkanes. Hence the drawback of the method described in Section A was overcome by employing nitroalkenes as starting materials. 3SnH in water under microwave irradiation, led to excellent yields of corresponding nitroalkanes (Scheme 2). The nitroalkenes substituted even by bulky groups at C-1 & C-2 were converted into corresponding nitroalkanes. Hence the drawback of the method described in Section A was overcome by employing nitroalkenes as starting materials. Scheme 2. Microwave assisted reduction of nitroalkenes to nitroalkanes in Bu3SnH-water In Section C, the synthesis of nitroalkenes via dehydration of 2NAs in a K Scheme 3 ). Thus, the dehydration of 2NAs has been accomplished under relatively mild conditions. (It was observed that the 2NAs bearing bulky groups underwent the retro-Henry reaction rather than dehydration.) 2CO3-water system has been described. This conversion was accomplished at 0-5 °C in 5-30 minutes, the nitroalkenes being isolated in good yields (Scheme 3). Thus, the dehydration of 2NAs has been accomplished under relatively mild conditions. (It was observed that the 2NAs bearing bulky groups underwent the retro-Henry reaction rather than dehydration.) Scheme 3. Dehydration of 2-NAs in aqueous K2CO3 solution Chapter III describes the chemoselective reduction of ketoaldehydes. This was serendipitously discovered during attempted enantioselective reduction of prochiral ketones using amino acid-NaBH Scheme 4 ). The method provides a mild and efficient route for the chemoselective reduction of aldehydes under aqueous basic conditions. 4-Na2CO3 in water. When equimolar quantities of aldehyde and ketone were added to a solution NaBH4 in aqueous Na2CO3 at ambient temperature, the aldehydes were selectively reduced. Good yields of primary alcohols were generally observed with excellent chemoselectivities. Extension of this study to the selective reduction of ketoaldehydes under the above reaction conditions furnished ketoalcohols in > 70% yields with > 80% chemoselectivities (Scheme 4). The method provides a mild and efficient route for the chemoselective reduction of aldehydes under aqueous basic conditions. Scheme 4. Chemoselective reduction of ketoaldehydes with NaBH4-Na2CO3 in water Chapter IV deals with deprotection of various acetals, thioacetals and tetrahydropyranyl (THP) ethers in hexane under ambient conditions, by employing chloral hydrate as reagent. Chloral hydrate is a crystalline solid with pK2 When a a 9.66.stirred suspension of excess chloral hydrate in hexane was treated with the acetal, thioacetal or THP ether, the corresponding aldehyde, ketone and alcohol were obtained in good to excellent yields (stirred suspension of excess chloral hydrate in hexane was treated with the acetal, thioacetal or THP ether, the corresponding aldehyde, ketone and alcohol were obtained in good to excellent yields (stirred suspension of excess chloral hydrate in hexane was treated with the acetal, thioacetal or THP ether, the corresponding aldehyde, ketone and alcohol were obtained in good to excellent yields ( Scheme 5. Chloral hydrate catalyzed hydrolysis of acetals, thioacetals including THP ethers Part-II:- Mechanistic Studies on Phase Transfer Catalysis and The Hydrophobic Effect Part-II is in two chapters. Chapter V describes a study of the mechanism of the phase transfer catalyzed (PTC) nucleophilic reaction of cyanide ion with alkyl halides in decane ( Scheme 7 ). In the extraction mechanism proposed earlier,3 the PTC forms the mixed species, tributylhexadecylphosphonium cyanide (THPB), which is believed to be more soluble in decane than is the starting cyanide. A problem with this explanation is that the positive free energy of transfer of the cyanide ion from the aqueous to the organic phase, which is unlikely to be offset by solvation energy of the hexadecyl and butyl groups. Scheme 6. Cyanide displacement reaction of 1-chloro octane3 The present studies explore the possibility that the reaction occurs via the formation of aggregates resembling reverse micelles ( Figure 1 ). In these, the hydrocarbon residues point outwards, with the ionic species ensconced in a deeply embedded interior along with a certain number of water molecules. Thus, the ionic species are not only shielded from the organic medium, but also stabilized in a relatively polar micro-environment (largely via dipolar interactions and hydrogen bonding). It is assumed that this stabilization energy surpasses the positive free energy of transfer of cyanide ion from aqueous to the organic phase. Figure 1. Typical representation of cyanide displacement reaction in THPB-decane-water micellar pool In fact, NMR studies on the structural dynamics of THPB in solution offered evidence of aggregation. Also, a correlation between the structures of catalyst and reactant was observed in studies with various other PTC’s. Chapter VI deals with the mechanism of the Diels-Alder reaction (DAR) in water. The concept of the hydrophobic effect (HE)4 and preferential hydrogen bonding of water with the polarized transition state5 have been invoked to explain the apparent acceleration of Diels-Alder reactions in water. The present studies explore the possibility that the highly polar water microenvironment stabilizes the transition state. Semi-quantitative rate studies of DAR involving water soluble reactants indicate that the possible role of solvation and hydrogen bonding on the polarized transition state as the key factor in the rate enhancement of water mediated DAR. The DAR in the presence of a catalytic amount of water along with the organic solvent catalyzed the reaction more efficiently, as compared to the reaction in pure organic solvent. It was also observed that there was a prominent effect of traces of water on the rate in solvent-free conditions. .

L’utilisation de semi-conducteurs organiques dans les dispositifs électroniques offre d’intéressantes perspectives. En effet, ils permettent d’alléger le poids de ces dispositifs en plus de diminuer grandement le coût de leur fabrication. Cependant, une des principales problématiques associées à ces semi-conducteurs organiques est leur procédé de fabrication qui requiert des solvants organiques toxiques et de multiples étapes de synthèse. Dans ce travail, un nouveau procédé de synthèse respectueux de l’environnement a été mis au point. Une seule étape était nécessaire à la préparation des semi-conducteurs, en utilisant la réaction de polycondensation entre une diamine et un dialdéhyde. Cette réaction a été réalisée à température ambiante, dans un solvant vert, l’éthanol, et sans utilisation de catalyseurs, minimisant ainsi la consommation énergétique et utilisant un milieu réactionnel de source renouvelable et peu toxique. Après leur dopage, ces polymères ont présentés des propriétés de conduction comparables à celles des principaux semi-conducteurs organiques. La deuxième partie de cette thèse a été consacrée à l’étude de l’utilisation du papier comme support pour les dispositifs d’électronique organique; s’affranchissant ainsi de l’utilisation de substrats généralement non biodégradables et/ou de sources non renouvelables (plastique ou verre). Deux stratégies ont été utilisées à cette fin. La première consistait en un dépôt direct des polymères semi-conducteurs à la surface de filaments de cellulose. La deuxième est basée sur la création d’un lien covalent entre les semi-conducteurs et la pâte Kraft, en utilisant la réaction de cycloaddition 1,3-dipolaire de Huisgen catalysée par le cuivre (CuAAc). / The use of organic semiconductors in electronic devices offers interesting prospects. Indeed, they make it possible to lighten the weight of these devices in addition to greatly reducing the cost of their manufacture. However, one of the main problems associated with these organic semiconductors is their manufacturing process, which requires toxic organic solvents and multiple synthesis steps. In this work, a new environmentally friendly synthesis process has been developed. A single step was necessary for the preparation of the semiconductors, using the polycondensation reaction between a diamine and a dialdehyde.This reaction was carried out at room temperature in ethanol, a green solvent and without the use of catalysts, thus minimizing energy consumption and using a reaction medium from a renewable and low-toxicity source. After their doping, these polymers exhibited conduction properties comparable to those observed for conventional organic semiconductors.The second part of this thesis was devoted to the study of the use of paper as a support for organic electronics devices; hus avoiding the use of generally non-biodegradable and/or non-renewable substrates (plastic or glass). Two strategies have been used to this end. The first consisted of a direct deposit of the semiconducting polymers to the surface of cellulose filaments.The second is based on the creation of a covalent bond between the semiconductors and the Kraft pulp, using the copper-catalyzed Huisgen 1,3-dipolar cycloaddition reaction (CuAAc).

Plusieurs ligands dérivés de la D-glucosamine, conçus pour différentes réactions catalytiques,ont été synthétisés. Les ligands pour la catalyse homogène basés sur 1,2-glucodiamine ontété préparés, et utilisés dans des réactions d'alkylation allylique, d'hydrogénation et d'additionde Michael.La D-glucosamine a utilisee pour la preparation de catalysateur type de SPAC (SupportedAqueous Phase Catalyst). Ce catalysateur hétérogène été utilisé avec de très bons résultatsdans les réactions de couplage croisé de Suzuki Miyaura. Le catalyseur a également étérecyclé. Des essais de préparation de ligands greffés sur une matrice de silice de type SBA-15ont été réalisés ainsi que des ligands à base de poly (éthylène) glycol. / Several ligands derived from D-glucosamine, designed for different catalytic reactions havebeen synthesized. The ligands for homogeneous catalysis based on 1,2-glucodiamine wereprepared, and used in reactions of allylic alkylation, hydrogenation and Michael addition.Supported Aqueous Phase Catalyst (SAPC) system was prepared from D-glucosamine anduse with very good results in Suzuki Miyaura cross coupling reactions. Catalyst was alsorecycled. Attempt to prepare ligands grafted on SBA-silica matrix were made as well asligands containing poly(ethylene) glycol moiety.

No description available.

Main group polycations and transition metal clusters had traditionally been synthesized via high-temperature routes by performing reactions in melts or by CTR, at room-temperature or lower temperature by using so-called superacid solvents, and at room-temperature in benzene–GaX3 media. Considering the major problems associated with higher temperature routes (e.g. long annealing time, risk of product decomposition, and low yield) and taking into account the toxicity of benzene and liquid SO2 in room-temperature or lower temperature synthesis, a soft and sustainable chemical approach has been developed, employing a Lewis-acidic IL [bmim]Cl/AlCl3. This new alternative reaction medium has proven to be an excellent solvent system for the single–step synthesis of main group polycations and transition metal clusters. X-ray diffraction and Raman spectroscopy have been used for the structural characterization of the isolated compounds. Physical properties and quantum chemical calculations of some of the compounds have also been carried out.