Cross-Linked Polyamine from Imidazolium-Based Materials: A Simple Route to Useful Catalytic Materials

Cross-linked polyamine-based materials were easily prepared by reduction of the corresponding cross-linked imidazolium-based materials with sodium borohydride in hot ethanol. Overall, the synthetic procedure is based on the polymerization of a suitable bis-vinylimidazolium salt with or without a suitable support, such as silica or silica-coated magnetic nanoparticles (-Fe2O3@SiO2), followed by reduction. This simple approach allows the synthesis of materials based on a network of secondary and tertiary amines. Materials were characterized by C-13 cross-polarization magic angle spinning NMR (C-13 CPMAS NMR), proton spin-lattice relaxation times in the rotating frame (T1H) and thermogravimetric analysis (TGA). Cross-linked polyamine-based materials were used as recoverable catalyst for Knoevenagel reaction. High yields of the condensation products were obtained and up to 11 cycles were carried out.