Magnetic mesoporous silica supported propyl amine: An efficient catalyst for Knoevenagel reaction

The Knoevenagel reaction is one of the most important method for formation of carbon–carbon double bond between activated methylenes and carbonyl compounds[1, 2]. Traditionally, several homogeneous catalysts such as pyridine, [Bmim][OH], diethyl amine and basic ionic liquids, benzimidazole, piperidine acetate and acetic acid were applied for this process [1-4]. However, these suffer from limitations of non-catalyst recoverability, difficult product separation and harsh reaction conditions. Accordingly, a set of different recoverable heterogeneous catalysts were designed and used for this reaction. In continuous of these studies, herein, a novel aminefunctionalized magnetic mesoporous silica ([e-mail]2@PrNH2) is prepared, characterized and applied as an efficient nanocatalyst for the Knoevenagelcondensation (Scheme 1). This catalyst was prepared via modification of magnetic iron oxide nanoparticles with mesoporous silica followed with treatment with 3-aminopropyl-triethoxysilane (APTES). The [e-mail]2@PrNH2 was characterized using scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), Fourier transform infrared spectroscopy (FTIR) and energydispersive X-ray spectroscopy (EDX). This was successfully used as an effective catalyst in the condensation of aldehydes with ethylcyano-acetate to deliver corresponding Knoevenagel products. The recoverability, reusability and stability of the designed catalyst have been also studied under applied conditions