Nano Ag-doped magnetic-Fe3O4@mesoporous TiO2 core-shell hollow spheres: synthesis and enhanced catalytic activity in A3 and KA2 coupling reactions

Nano Ag-doped Fe3O4@mesoporous TiO2 core-shell hollow spheres (h-Fe3O4@m-TiO2/Ag) were efficiently prepared. They were fully characterized by FT-IR, FE-SEM, EDX, ICP, TGA, XRD, and BET methods. In addition, their magnetic properties were determined by means of the VSM method. Also, the rho (shell) of the prepared hollow Fe3O4 micro-particles was calculated, being found just slightly lighter than that of solid sphere-like Fe3O4. The catalytic activity of this novel catalyst system was successfully examined as a novel catalyst system in A(3) coupling reactions (aldehyde + amine + acetylene). This highly active magnetic catalyst was easily separated using an external magnet and re-used in five consecutive runs in the model reaction without appreciable loss of its catalytic activity. [GRAPHICS] .