Palladium and copper supported on mixed oxides derived from hydrotalcite as reusable solid catalysts for the Sonogashira coupling

Magnesium oxide and mixed aluminium-magnesium oxide derived from layered hydrotalcite were used as supports of copper and palladium in various amounts. These solids were used as heterogeneous and reusable solid catalysts for the Sonogashira coupling of iodobenzene and phenyl acetylene in DMF/water as solvent. The activity of MgO was somewhat higher than that of Mg-Al hydrotalcite. The solid catalysts could be reused, but then a decrease in catalytic activity was observed. On reuse, the layered hydrotalcite structure was reconstituted, but no palladium particles were detectable by TEM. Experiments designed to test potential metal leaching showed that the system was heterogeneous. A three-phase test anchoring a iodopheryl reagent to a silica also confirmed that Sonogashira coupling occurred on the solid mixed-oxide catalyst. (c) 2006 Elsevier Inc. All rights reserved.