Pd-PVP colloid as catalyst for Heck and carbonylation reactions: TEM and XPS studies

• DOI: 10.1016/j.jcat.2004.11.003
• Publication Date: 2004-12-28T18:44:54Z
• Authors: A GNIEWEK; A TRZECIAK; J ZIOLKOWSKI; L KEPINSKI; J WRZYSZCZ; W TYLUS
• Keywords: 01 natural sciences; 0104 chemical sciences

Abstract Pd-PVP colloid (stabilized with polyvinylpyrrolidone) with a diameter of 19.8 nm in [Bu4N]Br medium catalyzes Heck coupling of bromobenzene with butyl acrylate and methoxycarbonylation of iodobenzene reactions. Oxidative addition of PhI or PhBr to Pd-PVP as the first step of a catalytic reaction was confirmed by TEM and XPS measurements. TEM studies showed significant reduction of Pd nanoparticle size after their reaction with PhX (X = I, Br) and [Bu4N]X (X = Cl, Br, I). The biggest shift of the center of nanoparticle size distribution, from 19.8 nm to 7.6 nm, was found when Pd-PVP reacted with PhI and [Bu4N]Br. The formation of [Bu4N]2[Pd(Ph)Br3]- and [Bu4N]2[PdBr4]-type complexes in that system was evidenced by XPS and UV–vis spectra.