Mesoporous Silicates as Grubbs Catalyst Scavengers

Significance

A mesoporous silicate functionalized with aminopropyltriethoxy silane was developed for the removal of residual ruthenium species from a reaction mixture of Grubbs’ olefin metathesis. Thus, the crude mixture obtained upon completion of the metathesis (a substrate: 0.50 mmol; 2 h at r.t.) was treated with the SBA-15-supported propylamine in THF. The mixture was filtered through a syringe filter to remove the scavenger, and the leaching of Ru in the filtrate was analyzed by ICP-MS. It was found that the scavenging gave a product with 0.2% (w/w) of Ru residue after treatments with 1 (twice). No silica-gel chromatography was required to bring the ruthenium content down to parts per thousand levels. The scavenging method was also applied to the removal of Ru from the reaction mixture of Noyori’s asymmetric hydrogenation.