Unsupported Nanoporous Copper Catalyst for the Carboxylation of Terminal Alkynes with Carbon Dioxide

Abstract An unsupported nanoporous copper catalyst (CuNPore) with highly bicontinuous nanostructure was prepared by a chemical dealloying method. Various characterization methods were used to investigate the structure and composition of CuNPore, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). Active species of cuprous oxide were found on the surface of CuNPore catalyst. The nanoporous structure and the presence of Cu(I) enable CuNPore to catalyze the carboxylation reaction of terminal alkynes with CO 2 under mild conditions. A wide range of terminal alkynes were tolerated to afford the alkynyl carboxylic acids in good to excellent yields. CuNPore catalyst can be easily recovered and recycled five times without any loss of activity.