Periodic Mesoporous Silica-Supported Recyclable Rhodium-Complexed Dendrimer Catalysts

Polyamidoamine (PAMAM) dendrimers up to the third generation were grown for the first time inside the channels of a large-pore (6.5 nm) MCM-41 silica. Indepth characterization of such materials showed that the dendrimers grew inside the channels. The third generation was found to almost completely fill the pore system. The supported dendrimers of generations 0, 1, and 2 were phosphinomethylated and then complexed with rhodium. The G(0) and G(1) materials were found to be very active in olefin hydroformylation. The hydroformylation of 1-octene was accomplished with a turnover frequency of 1800 h-1 at 70 C and the catalyst could be recycled several times without loss in activity.