A convenient method to immobilize 4-dimethylaminopyridine on silica gel as a heterogeneous nucleophilic catalyst for acylation

A catalyst comprised of 4-dimethylaminopyridine (DMAP) functionalized silica gel (SG-DMAP) was prepared via a convenient N-alkylation of 4-methylaminopyridine (MAP) with γ-chloropropylated silica gel promoted by potassium iodide. FT-IR, TG, SEM results illustrated that the DMAP was successfully immobilized on silica gel and the BET result suggested the pore structure was not altered after immobilization process. The highest immobilization amount of 0.75 mmol/g was obtained at 130 °C for 12 h. Activity test demonstrated that silica gel immobilized DMAP could be serve as a heterogeneous catalyst for the acylation with significant activity and stability.