Comparison of the Catalytic Activity of Copper Nanostructures in Friedel‐Crafts‐Type Condensation Reactions

Abstract The catalytic activity of copper nanostructures in the condensation reaction of selected indoles and aldehydes or ketones was investigated. Cu(acac) 2 , zeolite Y‐encapsulated Cu(acac) 2 , free and zeolite Y‐encapsulated CuO nanoparticles, and Cu 2 O nanoparticles with different size and shapes were prepared successfully and characterized by means of UV‐Vis spectroscopy, Fourier‐transform infrared spectroscopy (FTIR), diffuse reflectance spectroscopy (DRS), X‐Ray diffraction analysis (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X‐Ray analysis (EDX). Cubic Cu 2 O nanoparticles showed superior activity as a heterogeneous catalyst compared to other catalytic systems. Excellent yields of the desired bis(indolyl)methanes were obtained via condensation reaction of indoles and aldehydes in presence of cubic Cu 2 O nanoparticles under mild reaction conditions and the catalyst retained activity for six successive catalytic runs.