Mercaptopropyl-modified mesoporous silica: a remarkable support for the preparation of a reusable, heterogeneous palladium catalyst for coupling reactions.
The functionalization of SBA-15 with mercaptopropyl trimethoxysilane leads to a material capable of absorbing Pd from organic and aqueous solutions. The resulting Pd-loaded material acts as a catalyst for the Suzuki-Miyaura and Mizoroki-Heck coupling reactions. Leaching studies show that the filtrate contains as little as 3 ppb Pd after reaction. Aminopropylated silica is an effective scavenger, and catalyst for the Mizoroki-Heck reaction, but leaching is significant (35 ppm), illustrating the importance of the thiol ligand to retain Pd on the surface. Heterogeneity tests such as hot filtration experiments and three-phase tests show that the reaction is occurring predominantly via surface-bound Pd.
Crudden
Cathleen M
CM
Queen's University Department of Chemistry, 90 Bader Lane, Kingston, Ontario, Canada K7L 3N6. cruddenc@chem.queensu.ca
Sateesh
Mutyala
M
Lewis
Roxanne
R