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

Abstract

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 °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 13 C 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 γ-valerolactone (GVL), Cyrene TM and ethylene carbonate proved to be excellent reaction media for Heck coupling, whereas EtOH/H 2 O 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.

Preparation and Application of Green Sustainable Solvent Cyrene

“…Watson et al were the first to use Cyrene to replace DMF as the solvent in a Pdcatalysed cross-coupling reaction [72]. Then, other researchers observed that Cyrene could be an excellent alternative medium for the Sonogashira cross-coupling reaction [86,87]. A greener alternative for the synthesis of ureas was proposed, and it was proven that Cyrene could possibly be used industrially as a solvent [88].…”