Veronika Zinovyeva - Polypyrrole - Palladium Nanoparticles Composite as Efficient Catalyst for Suzuki-Miyaura Coupling

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  Publication Details (including relevant citation   information):

  J.   Mol. Catal. A: Chem. 2012,   353-354, 50-57.

    Magdesieva, T. V.; Nikitin, O. M.; Levitsky, O. A.; Zinovyeva, V.   A.; Bezverkhyy, I.; Zolotukhina, E. V.; Vorotyntsev, M.   A.


  Synthesis of a new hybrid material (Pd/PPy) composed of   polypyrrole globules with uniformly incorporated Pd nanoparticles   via direct redox reaction between pyrrole and   Pd(NH3)4Cl2 in water has been   recently reported (V.A. Zinovyeva, M.A. Vorotyntsev, I.   Bezverkhyy, D. Chaumont, J.-C. Hierso, Adv. Funct. Mater. 21   (2011) 1064–1075). In the actual study, this procedure has been   extended to synthesize a series of Pd/PPy powders with variable   palladium content and morphological parameters. Depending on the   monomer-to-oxidant ratio in reaction mixture, average diameters   of Pd and PPy particles may change in the ranges of 1.25–1.45 and   27–62 nm, respectively, the Pd concentration being within   33.5–42.0 wt.%. In general terms, decrease of the   monomer-to-oxidant ratio led to formation of the Pd/PPy hybrid   material with smaller diameters of both components and a higher   Pd loading. The Pd/PPy composites have been studied in   Suzuki–Miyaura coupling and showed high catalytic efficiency.   Aryl iodides, bromides and chlorides are active. The reaction can   be performed using arylboronic acids or tetraarylborates, both in   organic solvents and in water, thus making the process   ecologically friendly. The recycling of the catalyst is possible   if its particles are immobilized on the graphite support. The   comparison of two samples revealed that Pd/PPy nanocomposite with   the diameter of PPy spheres of about 30 nm is more efficient in   catalysis, as compared to the sample with bigger PPy spheres   (about 60 nm), due to transport limitations for reagents inside   the polypyrrole sphere in the latter case. For   palladium/polypyrrole nanocomposites with the small diameter of   PPy sphere, which are easily penetrable for the reagents and in   which all Pd nanoparticles are active, Pd content in polypyrrole   spheres does not influence the yield of biaryls: the more is the   Pd content in polypyrrole spheres, the less amount of catalyst is   necessary to obtain the same yield of biaryl.

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