Dual Responsive Sustainable Cu2O/Cu Nanocatalyst for Sonogashira and Chan-Lam Cross-Coupling Reactions.

Cu₂O/Cu nanocatalyst was prepared by simple in situ gas phase H₂O/O₂ stimulating approach via deposition of Cu₂O on the surface of Cu nanoparticles (NPs) using aqueous extract of papaya peel. The synthesized hybrid copper catalyst offers an efficient methodology for Pd-free Sonogashira and Chan–Lam cross-coupling reactions. A site-selective type catalytic activity was observed in Sonogashira coupling reaction by performing a controlled experiment using Cu (0) and the hybrid Cu₂O/Cu nanocatalyst. It is characterized by solid UV-visible spectroscopy, Fourier transform infrared (FTIR spectroscopy), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). XRD and XPS analysis confirmed the formation of the Cu (0) and Cu₂O NPs. The Cu₂O/Cu NPs appear two different phases distributed like a lamellar sheet stacked one above the other. The presence of Cu₂O phase in hybrid nano catalyst provides an attractive advantage highlighting a Cu (I)-Cu (0) synergistic interaction in the respective cross-coupling reaction. [ABSTRACT FROM AUTHOR]