49 research outputs found

    Palladium–mediated organofluorine chemistry

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    Producción CientíficaThe substitution of fluorine for hydrogen in a molecule may result in profound changes in its properties and behaviour. Fluorine does not introduce special steric constraints since the F atom has a small size. However, the changes in bond polarity and the possibility of forming hydrogen bonds with other hydrogen donor fragments in the same or other molecules, may change the solubility and physical properties of the fluorinated compound when compared to the non-fluorinated one. Fluorine forms strong bonds to other elements and this ensures a good chemical stability. Altogether, fluorinated compounds are very attractive in materials chemistry and in medicinal chemistry, where many biologically active molecules and pharmaceuticals do contain fluorine in their structure and this has been shown to be essential for their activityJunta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA302U13)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA256U13

    Theorical study of coupling reactions catalyzed by transition metals

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    Ce travail consiste en l'étude théorique DFT des mécanismes de couplage. Le couplage déshydrogénant de stannanes implique la formation in situ d'un stannylène, formation possible grâce à l'inertie de la paire libre et au caractère acide de Lewis des stannylènes. Le couplage entre un carboxylate aromatique et un arène Ar-H commence par la décarboxylation en 2 étapes (isomérisation et désinsertion de CO2) sur un complexe de Pd(II) et se poursuit par une étape de CMD. Celle-ci est facilitée par la présence de fluors en ortho sur Ar-H essentiellement en raison du renforcement de la liaison M-C qu'ils induisent. Le couplage entre un arène et un alcyne catalysé par Ni(0)L présente une étape originale de transfert d'hydrogène de l'arène sur l'alcyne concerté avec la création de deux liaisons M-C (M-aryl et M-vinyl). Cette étape est à nouveau associée à une barrière d'activation plus basse en présence de fluors sur l'arène. L'hydroboration avec ouverture de cycle d'alkylidenecyclopropane en présence de Rh(I) nécessite la création de deux sites vacants pour que l'étape souhaitée d'ouverture de cycle soit favorisée par rapport à une étape d'élimination réductrice C-B.This work is a theoretical study with DFT method of coupling reactions. The dehydrogenating coupling of stannanes proceeds via the formation of stannylene. This is made possible because of the chemical inertness of the lone pair and the Lewis acid character of stannylene. Coupling an aromatic carboxylate and an arene Ar-H on a Pd(II) complex is initiated by a 2-step reaction (isomerization and decarboxylation). The CMD reaction that follows is facilitated by ortho fluorine subtituents on the arene ArH because of the strengthening of the resulting Pd-C bond. The coupling between an arene and an alkyne by a Ni(0)L catalyst starts by an unusual hydrogen transfer from the arene to the alkyne, concerted with the formation of two NiC (aryl and vinyl) bonds. The energy barrier of this elementary step is lowered by fluorine subtituents on the arene. The hydroboration with ring opening of alkylidenecyclopropane in presence of Rh(I) complex is feasible only with two empty coordination sites during the key ring-opening step. Under these conditions, the ring opening is favored over the reductive elimination C-B

    Vídeo - Palestra com o Cônsul-geral da França, Jean-Paul Guihaumé, na FGV EPGE

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    No dia 08 de outubro de 2018, a EPGE Escola Brasileira de Economia e Finanças (FGV EPGE) recebeu o Cônsul-geral da França, Sr. Jean-Paul Guihaumé, para ministrar a palestra intitulada “A Importância da língua e da cultura francesas no mundo, hoje e amanhã”. O Diretor da FGV EPGE, Professor Rubens Penha Cysne moderou a palestra e após a apresentação o palestrante respondeu as perguntas do público. Mais informações sobre o evento podem ser obtidas em: https://eventosepge.fgv.br/pt/evento/23759/palestra-com-consul-geral-da-franca-a-importancia-da-lingua-e-da-cultura-francesas-n

    Vídeo - Seção de perguntas do público em Palestra com o Cônsul Geral da França na EPGE

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    No dia 08 de outubro de 2018, a EPGE Escola Brasileira de Economia e Finanças (FGV EPGE) recebeu o Cônsul-geral da França, Sr. Jean-Paul Guihaumé, para ministrar a palestra intitulada “A Importância da língua e da cultura francesas no mundo, hoje e amanhã”. O Diretor da FGV EPGE, Professor Rubens Penha Cysne moderou a palestra e após a apresentação o palestrante respondeu as perguntas do público. Mais informações sobre o evento podem ser obtidas em: https://eventosepge.fgv.br/pt/evento/23759/palestra-com-consul-geral-da-franca-a-importancia-da-lingua-e-da-cultura-francesas-n

    Vídeo - Seção de comentários em Palestra com o Cônsul-geral da França, Jean-Paul Guihaumé, na FGV EPGE

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    No dia 08 de outubro de 2018, a EPGE Escola Brasileira de Economia e Finanças (FGV EPGE) recebeu o Cônsul-geral da França, Sr. Jean-Paul Guihaumé, para ministrar a palestra intitulada “A Importância da língua e da cultura francesas no mundo, hoje e amanhã”. Após a palestra, o Gerente de Relações Internacionais da FGV, Professor Eduardo Marques; o Diretor Executivo da Câmara FGV de Mediação e arbitragem da FGV,Professor Julian Chacel e o Diretor da FGV EPGE, Professor Rubens Penha Cysne, fizeram comentários sobre o evento. O evento debateu o papel da língua e do patrimônio cultural francês no contexto internacional, bem como as perspectivas da francofonia no mundo globalizado. Mais informações sobre o evento podem ser obtidas em: https://eventosepge.fgv.br/pt/evento/23759/palestra-com-consul-geral-da-franca-a-importancia-da-lingua-e-da-cultura-francesas-n

    NUMERICAL SIMULATION OF THE CHARGE STATE EVOLUTION AND ENERGY LOSSES IN HEAVY ION BEAM-PLASMA INTERACTIONS

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    Un code numérique, de type Monte-Carlo, a été écrit afin d'analyser l'évolution de l'état de charge et de l'énergie d'un faisceau d'ions lourds traversant un plasma créé par laser. Nous présentons, tout d'abord, l'ensemble des processus physiques pris en compte lors de l'interaction, puis, traitons celle d'un faisceau de cuivre avec un plasma de carbone et avec un plasma d'aluminium.To analyse the charge state and energy evolutions of heavy ions travelling through a laser created plasma, a Monte-Carlo code has been written. A detailed account of the physical processes involved during the interaction is given here. The code is applied to the interaction of a Cu-beam with a C-plasma and with an Al-plasma
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