Humins-Like Solid Support for Palladium Immobilization: Highly Efficient and Recyclable Catalyst for Cross-Coupling Reactions

In the present work, a new humins-like resin was prepared using 2,5-bis(hydroxymethyl)furan (DHMF) and maleic anhydride in 2 min at 110 degrees C. Such a new material was used as a solid support for palladium immobilization. For metal anchoring, encapsulation was the method of choice and palladium was encapsulated by in-situ polymerization. This resulting Pd@DHMF-based catalyst was characterized by solid-state C-13 NMR, FT-IR, SEM, TGA, DSC, XRD, and XPS. To demonstrate proof of concept, Heck and Suzuki cross-coupling reactions were selected to evaluate the activity and reusability of the catalyst. Green solvents such as gamma-valerolactone (GVL), Cyrene (TM) and ethylene carbonate proved to be excellent reaction media for Heck coupling, whereas EtOH/H2O was preferred for Suzuki coupling. Yields of up to 99 % were obtained in both cases. The recyclability of the Pd@DHMF-based catalyst was also demonstrated, 7 cycles have been achieved without loss of catalytic activity in both Heck and Suzuki reactions.