Search

PdCl2(PPh3)2 in a mixture of water and poly(ethylene glycol) (PEG-2000) is shown to be an extremely active catalyst for the carbonylative Sonogashira coupling reaction of aryl iodides with terminal alkynes. The reaction can be conducted under an atmospheric pressure of carbon monoxide at 25 °C with Et3N as a base, yielding a variety of alkynyl ketones in good to excellent yields. Application of this synthetic method to prepare flavones from o-iodophenol and terminal alkynes was also achieved. The isolation of the products is readily achieved by extraction with diethyl ether, and the PdCl2(PPh3)2/PEG-2000/H2O system can be easily recycled and reused six times without any loss of catalytic activity. [ABSTRACT FROM AUTHOR]

A novel particle-on-alloy nanomaterial has been designed and successfully synthesized for oxygen reduction (ORR) with high activity and long-term stability, in which well-isolated Pt nanoparticles are supported by amorphous NiCo nanoalloys. The Pt-on- NiCo nanostructures are prepared through the artificial active collodion membrane by one-step method, and experimental data reveals that Pt is isolated and spreads onto the amorphous NiCo nanosupport, and not only Pt but also Ni and Co are metallic in the Pt-on-NiCo nanostructures. The optimized Pt53-on-NiCo nanostructures show higher activities in both the onset potential and kinetic current density toward the ORR relative to the commercial Pt reference catalysts because the Pt-on-NiCo catalyst could lower the OHad, which is considered to inhibit the ORR toward water. Meanwhile, Pt-on-NiCo nanostructures exhibit relatively long-term stability with only ~8% loss in electrochemical surface area (ECSA) for Pt [ABSTRACT FROM AUTHOR]