PdCu bimetallic nanoparticles with a diameter of about 3 nm are prepared and supported on a polymeric vinylimidazole ligand modified magnesium oxide. This new material is characterized using different analysis such as XRD, XPS, CHNS, TEM, SEM, and EDXmapping. PdCu supported on MgO (MgO@PdCu) exhibits high catalytic activity in the Sonogashira coupling reaction of aryl iodides, bromides and chlorides with low Pd loading (0.05 to 0.2mol%). This catalyst is recovered and recycled for 11 consecutive runs preserving its catalytic activity in the model reaction of iodobenzene with phenylacetylene for at least 8 cycles. Reused catalyst is characterized with TEM, XPS and EDX showing preservation of the catalyst structure. Using hot filtration and PVP poisoning tests, the catalyst shows a heterogeneous behavior for the model reaction.
Novel magnesium oxide-carbon quantum dots have been synthesized and used for the formation and stabilization of palladium nanoparticles. This highly water dispersible material, Pd@MgO-CQD, has been used as an active catalyst for Suzuki coupling of aryl bromides at room temperature and aryl chlorides at 80 °C in water. Using fluorescence emission of the material, a new protocol for determine of Pd loading and leaching in catalyst preparation and recycling process was developed.
Gold nanoparticles supported on imidazole‐modified bentonite, Bent@Im@Au NPs, has been developed for the first time as an effective heterogeneous catalyst for the synthesis of propargylamines under mild reaction conditions in water at a loading of 0.07 mol % of Au. Various techniques such as X‐ray diffraction, high‐resolution transmission electron microscopy, Fourier transform infrared spectroscopy, and element mapping by scanning electron microscopy were used to determine the physicochemical properties of the catalysts. The new gold catalyst was found to be highly active providing high to excellent yields of A3 coupling products via the reactions of various aldehydes, having electron‐withdrawing as well as electron‐donating substituents, with different amines and alkynes. The catalysts can be easily recovered and reused without significant loss of activity and the recycled catalyst was characterized.
Green synthesis of carbon quantum dots from vanillin for modification of magnetite nanoparticles and formation of palladium nanoparticles: Efficient catalyst for Suzuki reaction,
A one-pot, tandem oxidation-Wittig procedure has been developed in which the reacting components are generated in situ from alcohols, triphenyl phosphine and ethyl bromoacetate using barium manganate as a mild oxidizing agent without the addition of an external base.
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