Palladium supported on an amphiphilic porous organic polymer: a highly efficient catalyst for aminocarbonylation reactions in water†
Exploring environmentally friendly, efficient and recyclable heterogeneous catalysts for organic reactions in aqueous media is important for the development of green and sustainable processes. In this work, an amphiphilic porous organic polymer supported palladium catalyst (Pd@UPOP) was synthesized via a facile urea-forming condensation of commercially available 3,3′-diaminobenzidine and 1,4-phenylene diisocyanate, followed by immobilizing palladium acetate at room temperature. Physico-chemical characterization suggested that the obtained material possessed a good porous structure and amphiphilic properties. Aminocarbonylation of aryl iodides with amines in water showed that Pd@UPOP is more active than previously reported heterogeneous palladium catalysts. Under balloon pressure of carbon monoxide, a palladium catalyst loading as low as 0.5 mol% was sufficient for a 98% yield of N,N-diethylbenzamide in the model reaction, corresponding to a high turnover frequency of 98 h−1. The catalyst could be used for at least five consecutive runs with the catalytic activity being recovered easily after simple manipulations.