Cobalt supported on alumina as green catalyst for Biginelli reaction in mild conditions: Effect of catalyst preparation method

Abstract

Cobalt supported on alumina (10 wt% Co/Al2O3) was synthesized by three different methods; sol-gel (SG), microemulsion (ME) and impregnation (IMP). The materials were characterized by the Brunauer-Emmett-Teller (BET) method, X-ray diffraction (XRD), X-ray fluorescence, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. Their catalytic activity was investigated toward the formation of Biginelli reaction products, 3,4-dihydropyrimidin(1H)-ones (DHPMs). The catalysts were found to be efficient for this reaction with yields between 50% and 71% and can be reused without great loss of efficiency. Among the catalytic systems, that prepared by the SG method is the most active with 71% of DHPMs yield under solvent free conditions at 100°C for 1 h of reaction time.