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    Monodisperse palladium nanoparticles supported on chemically derived graphene: highly active and reusable nanocatalysts for Suzuki{Miyaura cross-coupling reactions
    (2015) Metin, Önder; Durap, Feyyaz
    Addressed herein is the catalysis of monodisperse palladium nanoparticles (NPs) supported on chemically derived graphene (CDG) for the Suzuki{Miyaura cross-coupling of phenylboronic acid and various aryl halides. Monodis- perse Pd NPs were synthesized by the solution phase reduction of palladium(II) acetylacetonate with morpholine borane complex in oleylamine and deposited on CDG via the liquid phase self-assembly method. Colloidal Pd NPs and CDG-Pd catalyst were characterized by TEM, XRD, SEM, and ICP-MS analyses. The CDG-Pd catalyst showed high activity in the Suzuki{Miyaura cross-couplings of different aryl halides including iodides, bromides, and even chlorides with phenyl- boronic acid under mild conditions. More importantly, the reusability experiments revealed that CDG-Pd catalyst was highly durable by almost maintaining its inherent activity after the 15th catalytic cycle.
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    Öğe
    New route to synthesis of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Heck and Suzuki cross-coupling reactions
    (Wiley, 2009) Durap, Feyyaz; Metin, Önder; Aydemir, Murat; Özkar, Saim; 0000-0003-0899-1948; 0000-0003-1622-4992
    Herein we report a new method for the synthesis and characterization of PVP-stabilized palladium(0) nanoclusters and their enhanced catalytic activity in Suzuki coupling and Heck reactions of aryl bromides with phenylboronic acid and styrene, respectively, under mild conditions. The PVP-stabilized palladium(0) nanoclusters with a particle size of 4.5 +/- 1.1 nm were prepared using a new method: refluxing a mixture of potassium tetrachloropalladate(II) and PVP in methanol at 80 degrees C for 1 h followed by reduction with sodium borohydride. Palladium(0) nanoclusters prepared in this way were stable in solution for weeks, could be isolated as solid materials and were characterized by TEM, XPS, UV-vis, and XRD techniques. The PVP-stabilized palladium(0) nanoclusters were active catalysts in Heck and Suzuki coupling reactions of arylbromides with styrene and phenylboronic acid affording stilbenes and biphenyls, respectively, in high yield. Recycling experiments showed that PVP-stabilized palladium(0) nanoclusters could be used five times with essentially no loss in activity in the Heck and Suzuki coupling reactions. Copyright (C) 2009 John Wiley & Sons, Ltd.