Abstract:
Here we report, room temperature heterogeneous catalysis of the Suzuki-Miyaura cross-coupling reaction by a Pd sup(0) nanoparticle-immobilized porous organic polymer (TPU-Pd), providing excellent yields (up to 99%) using low catalyst loading. High nitrogen- and oxygen-donor content of triazine-based porous polyurethane (TPU) makes it an efficient porous polymer for Pd-immobilization and subsequent heterogeneous catalysis of C–C cross-coupling reactions. X-ray photoelectron spectroscopy of TPU-Pd showed characteristic binding energy peaks of Pd sup(0). Atomic absorption spectroscopy revealed 10.4 wt% of Pd sup(0) in TPU-Pd, and transmission electron microscopy images showed well-dispersed and facetted Pd sup(0) nanoparticles of size 5–20 nm. Catalysis of Suzuki-Miyaura reaction was observed to be completed in 3 h at 25 degrees C for a wide range of aryl halide substrates with phenylboronic acid, whereas increasing the reaction temperature to 80 degrees C largely allows decreasing the reaction time to 0.5-1 h. The porosity and surface area of the catalyst was not affected after catalysis, and the catalyst has been reused for five consecutive runs.
