Reusable functionalized polysiloxane-supported palladium catalyst for Suzuki–Miyaura cross-coupling

Palladium catalyst, obtained in the reaction of PdCl2(cod) with poly[(3-N-imidazolopropyl)methylsiloxane-co-dimethylsiloxane], was used in the Suzuki–Miyaura cross-coupling of aryl bromides with phenylboronic acid. Catalytic reactions, performed at 40–80 °C in water or 2-propanol/water mixture, led to high yields of 2-methylbiphenyl with TOF up to 25,000 h−1. In recycling experiments, excellent results were obtained in eight subsequent runs. With application of microwave heating, more than 95% of product was formed under mild conditions and short time. XRD, TEM, and XPS methods evidenced the presence of Pd(0) nanoparticles bonded to the polysiloxane support. Their important role in the catalytic process was indicated by the results of mercury poisoning test.

Palladium supported on siloxane polymer functionalized with imidazole groups efficiently catalyzes Suzuki–Miyaura reaction under mild conditions in environmentally friendly solvents such as water or a 2-propanol/water mixture. The catalyst is transformed to Pd(0) nanoparticles bonded to the polymer and showed very good recyclability.Figure optionsDownload high-quality image (48 K)Download as PowerPoint slideHighlights
► Palladium immobilized on imidazole-functionalized polysiloxane.
► Catalyst for Suzuki–Miyaura reaction under mild conditions.
► Good recyclability of the catalyst in 2-propanol/water mixture.
► Important role of immobilized Pd(0) nanoparticles in the catalytic process.
► Conventional heating versus microwaves.