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Phosphorus Functionalized Dendrimers and Hyperbranched Polymers: Is There a Need for Perfect Dendrimers in Catalysis?

Authors

  • Fabrizio Ribaudo,

    1. Supramolecular and Homogeneous Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, Amsterdam, 1018 WV, The Netherlands
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  • Piet W. N. M. Van Leeuwen,

    1. Supramolecular and Homogeneous Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, Amsterdam, 1018 WV, The Netherlands
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  • Joost N. H. Reek

    Corresponding author
    1. Supramolecular and Homogeneous Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, Amsterdam, 1018 WV, The Netherlands
    • Supramolecular and Homogeneous Catalysis, van't Hoff Institute for Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, Amsterdam, 1018 WV, The Netherlands
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Abstract

In this paper we describe the facile and straightforward covalent functionalization of commercially available dendritic poly(propylenimine) and hyper-branched poly(ethylenimine) with P-containing functional groups. The P-functionalized macromolecules have been applied as multivalent ligands in the Pd-catalyzed allylic substitution reactions (batch and continuous process) using either morpholine or thiophenol as nucleophile. Palladium complexes of all described molecules are active in allylic substitution reactions. The PEI functionalized polymers appear more sensitive to small changes in the P/Pd ratio than the PPI analogues, but form catalysts that are more active. When used in a continuous flow process the macromolecules are completely retained by the nanofiltration membrane, while the catalytic activity decreases with time because of palladium depletion. This is more severe for the allylic thiolation, probably because of the stronger affinity of sulfur for palladium, facilitating palladium leaching.

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