Grafted lanthanide amides: Versatile catalysts for various transformations

A series of silica-supported lanthanide (yttrium, lanthanum, neodymium and samarium) silylamides have been prepared using supports dehydroxylated at 250, 500 and 700 °C. According to the silica dehydroxylation temperature, different surface species distributions were obtained. These solids, under proper conditions, polymerise methyl methacrylate, ethylene, ɛ-caprolactone and isoprene. In the case of methyl methacrylate, structure–activity and -selectivity relationships for the surface species could be determined, while in the case of ethylene, no such information could be deduced, even if strong support effect was observed. These materials are also active in homocoupling of benzaldehyde to benzyl benzoate (Tischenko reaction) and in dimerisation of 1-heptyne into enyne. In these latter two cases, recycling of the catalytic system was successful.

Graphical abstractLanthanide (Y, La, Nd, Sm) silylamides grafted onto silica dehydroxylated at 250, 500 and 700 °C have been applied in methyl methacrylate, ethylene, ɛ-caprolactone and isoprene polymerisation, showing marked dependence of catalytic performances on the nature of the surface species. These materials are active for Tischenko reaction and 1-heptyne dimerisation, and proved to be recyclable catalytic systems. Figure optionsDownload full-size imageDownload as PowerPoint slide