Post-Modification of Copolymers Obtained by ATRP for an Application in Heterogeneous Asymmetric Salen Catalysis |
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Authors: | Erigene Bakangura Philippe Roger Rafaela S B Soares Mohamed Mellah Nadine Barroca-Aubry Anne-Chantal Gouget-Laemmel Franois Ozanam Ludovic Costa Jean-Pierre Baltaze Emmanuelle Schulz |
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Institution: | 1.Centre National de la Recherche Scientifique (CNRS), Institut de Chimie Moléculaire et des Matériaux d’Orsay, UMR 8182, Université Paris-Saclay, 420 Bâtiment, 91405 Orsay, France; (E.B.); (R.S.B.S.); (M.M.); (N.B.-A.); (L.C.); (J.-P.B.);2.Laboratoire de Physique de la Matière Condensée, Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique, Institut Polytechnique de Paris, 91120 Palaiseau, France; (A.-C.G.-L.); (F.O.) |
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Abstract: | Copolymers are valuable supports for obtaining heterogeneous catalysts that allow their recycling and therefore substantial savings, particularly in the field of asymmetric catalysis. This contribution reports the use of two comonomers: Azido-3-propylmethacrylate (AZMA) bearing a reactive azide function was associated with 2-methoxyethyl methacrylate (MEMA), used as a spacer, for the ATRP synthesis of copolymers, and then post-functionalized with a propargyl chromium salen complex. The controlled homopolymerization of MEMA by ATRP was firstly described and proved to be more controlled in molar mass than that of AZMA for conversions up to 63%. The ATRP copolymerization of both monomers made it possible to control the molar masses and the composition, with nevertheless a slight increase in the dispersity (from 1.05 to 1.3) when the incorporation ratio of AZMA increased from 10 to 50 mol%. These copolymers were post-functionalized with chromium salen units by click chemistry and their activity was evaluated in the asymmetric ring opening of cyclohexene oxide with trimethylsilyl azide. At an equal catalytic ratio, a significant increase in enantioselectivity was obtained by using the copolymer containing the largest part of salen units, probably allowing, in this case, the more favorable bimetallic activation of both the engaged nucleophile and electrophile. Moreover, the catalytic polymer was recovered by simple filtration and re-engaged in subsequent catalytic runs, up to seven times, without loss of activity or selectivity. |
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Keywords: | copolymerization ATRP post-modification salen heterogeneous asymmetric catalysis |
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