Utilisation des dendrimères en catalyse, étude de l’impact du dendrimère sur les catalyseurs greffés à sa surface
RIBOURDOUILLE, Yann (2004) Utilisation des dendrimères en catalyse, étude de l’impact du dendrimère sur les catalyseurs greffés à sa surface. Thèses de doctorat, Université Louis Pasteur.
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Dendrimers are highly branched macromolecules very well defined. These molecules possess applications in several scientific fields, including catalysis. The goal of this work is to study the impact of dendrimer onto catalysts immobilized in its periphery and more precisely the impact on the enantioselectivity of a reaction. With this aim in view, we functionalised the periphery of poly(amido)amine and poly(propylene)imine dendrimers with the Pyrphos ligand, which is a chiral diphosphine. The rhodium(I) complexes of these dendrimers were tested in asymmetric hydrogenation catalysis of alkenes. The enantioselectivity of this reaction was found to be independant of the size and type of the dendrimer. A methode of immobilisation of the dendritic rhodium(I) complexes on silica by electrostatic multilayers structures was developed and, immobilized monolayers of dendrimers were tested in asymmetric hydrogenation. The dendritic palladium(II) complexes were used in allylic substitution catalysis. A strong increase of the enantioselectivity as a function of the dendrimer size and a impact of the type of the dendrimer were observed. During the elucidation of this positive dendritic effect on the enantioselectivity, the implication of a bisdiphosphine palladium complex was underlined.
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