Immobilization of Ru(II) complex on functionalized SBA-15 and its catalytic performance in aqueous homoallylic alcohol isomerization

SBA-15-like mesoporous silicas functionalized with high contents of organic amine groups were synthesized by co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) in the presence of triblock copolymer P123 under acidic conditions. This method provided mesoporous silica with APTES: TEOS molar ratio ranging from 1:15 to 1:6. Further immobilization of dichlorotris(triphenylphosphine)-ruthenium(II) complex onto the functionalized support led to the formation of highly efficient and recoverable heterogeneous catalyst (Ru-AP). Characterizations using XRD, TEM and N2 adsorption–desorption isotherms demonstrated that the NH2-modified SBA-15 still retained highly ordered mesopore arrays even after immobilization of ruthenium complexes. Solid state 29Si MAS NMR and 13C CP MAS NMR and Raman investigations confirmed the presence of organic amine groups and RuCl2(PPh3)3 complex on silica frameworks. The Ru-AP heterogeneous catalyst exhibited almost the same activity and selectivity as the corresponding RuCl2(PPh3)3 homogeneous catalyst in the water mediated isomerization of 1-phenyl-3-buten-1-ol. The superiority of the Ru-AP was that it could be easily separated from the reaction system and used repetitively without obviously losing activity and selectivity at least for four times.

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