Synthesis and study of the catalytic applications in C–C coupling reactions of hybrid nanosystems based on alumina and palladium nanoparticles

Abstract

Nanostructured alumina has been treated under mild conditions with different quantities of [PdCl2(cod)] (cod=1,5-cyclooctadiene) to promote the formation of supported palladium nanoparticles which have been characterized by XRD, XRF, BET and TEM. The results show that the new hybrid materials, nano-Al2O3-Pd-20 and nano-Al2O3-Pd-50, consist of impregnated palladium nanoparticles onto aggregates of nanoparticles of alumina. The catalytic activity of the hybrid Pd-alumina materials has been tested in Suzuki–Miyaura C–C coupling reactions observing good conversion rates in the reactions of 3-bromoanisole with 4-carboxyphenylboronic acid or 4-vinylphenylboronic acid. The catalytic studies have been extended with experiments investigating the Pd loading influence. Catalyst recyclability tests show a slight decrease in activity after the first cycle in the reaction of 3-bromoanisole with 4-vinylphenylboronic acid. However, subsequent activity remains almost constant after five more consecutive catalytic cycles.