Highly Dispersed Palladium–Polypyrrole Nanocomposites: In‐Water Synthesis and Application for Catalytic Arylation of Heteroaromatics by Direct C–H Bond Activation

Abstract

Pd@PPy hybrid catalytic materials are synthesized in water via redox polymerization reaction of pyrrole with [Pd(NH3)4Cl2]. The nanocomposites formed are composed of highly dispersed palladium particles which are either zerovalent or easily reducible, and are embedded in spherical polypyrrole globules. A unique combination of high palladium dispersion (NP size: 2.4 nm) and elevated palladium content (35 wt%) is obtained. The components of these novel nanocomposites are characterized by means of FTIR, XPS, XRD, SEM, and TEM microscopy techniques. The process of formation in solution is also monitored using UV‐visible and DLS techniques. The application of these novel hybrid nanomaterials in the palladium‐catalyzed direct arylation of heteroaromatics is reported. High efficiency in C–C bond formation is obtained using these materials. Furans and thiophenes are arylated by using bromoarenes. Pd@PPy nanocomposites can efficiently couple n‐butyl furan and n‐butyl thiophene with bromobenzene and bromoquinoline, as well as with activated or deactivated electron‐poor and electron‐rich functionalized bromoarenes. Thus, a clean reaction process is developed that combines the absence of organic ligand in catalytic reactions and easy recovery of Pd@PPy nanocomposite via simple filtration. Preliminary kinetic and post‐catalysis studies suggest a molecular or colloidal soluble active species. These very active species are efficiently delivered by the nanocomposites and susceptible to a surprisingly uniform back redeposition within the polypyrrole support.

Ultrahigh Active Pd Nanocatalyst Supported on Core-Sheath Conducting Polymer/Metal Oxide Composite Nanorods

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Palladium nanoparticles deposited on silanized halloysite nanotubes: synthesis, characterization and enhanced catalytic property

“…Precious metals nanoparticles on catalyst supports have attracted considerable interest because they have been used in a number of catalysis applications, including transformation of organic12345 and fuel cells67891011. Reports indicate that the catalytic performance could be greatly enhanced by nanotube supports.…”

Stability of Prussian Blue–polypyrrole (PB/PPy) composite films synthesized via one-step redox-reaction procedure

“…As it was demonstrated in the synthesis of Pd/PPy composites via the same redox-reaction method [31,32], it is advantageous to use low concentrations of reactants, resulting in an extended period of the composite formation. Therefore, in the actual study, the concentrations of the reaction mixture were 0.1 mM Fe 3+ , 0.1 mM [Fe(CN) 6 ] 3− , and 0.5 mM Py, compared to 2 mM Fe 3+ , 2 mM [Fe(CN) 6 ] 3− , and 1-20 mM Py in [15].…”