Palladium(II)‐immobilized Triptycene based Hypercrosslinked Polymers: An Efficient, Green, and Reusable Heterogenous Catalyst for Suzuki‐Miyaura Cross‐coupling Reaction

Abstract

AbstractThe Suzuki‐Miyaura cross‐coupling (SMCC) involves the coupling of organohalides and organoboron molecules in the presence of Pd(II)‐based catalysts. Often SMCC reactions employ homogenous catalysts. However, such homogenous SMCC reactions are associated with certain limitations which has motivated design of effective and sustainable Pd(II)‐based heterogeneous catalytic systems. Herein, we report a systematic development of a Pd(II)‐immobilized and triptycene based ionic hyper crosslinked polymer (Pd@TP‐iHCP) and explored its application as a heterogeneous catalyst for SMCC reaction. Pd@TP‐iHCP has ample N‐heterocyclic carbene (NHC) pendants that anchor Pd(II) centres on the polymeric matrix. Pd@TP‐iHCP was characterized satisfactorily using FT‐IR, 13C CP‐MAS NMR, BET surface area analysis, SEM, EDX and HRTEM. The performance of Pd@TP‐iHCP as a heterogeneous catalyst for SMCC reactions was explored using various combinations of aryl boronic acids and aryl halides. Experimental results show that Pd@TP‐iHCP is associated with a moderately high surface area. It is an efficient catalyst for SMCC (in aqueous media) with a modest loading of 0.8 mol % Pd(II)‐catalyst since high yields of the expected products were obtained in shorter time intervals. Pd@TP‐iHCP also features excellent stability and catalyst recyclability since it could be re‐used for several cycles without any significant decrease in catalytic efficiency.