Sonocatalysis in solvent-free conditions: An efficient eco-friendly methodology to prepare N-alkyl imidazoles using amino-grafted NbMCM-41

3-Aminopropyl-trimethoxysilane (APMS) was loaded by grafting on MCM-41 matrices of various chemical compositions, silicate (MCM-41) and niobosilicate (NbMCM-41 with Si/Nb = 64). The materials were characterised by N2 adsorption/desorption, XRD, TG and test reactions: 2-propanol decomposition, acetonylacetone cyclisation and Knoevenagel condensation. The amino-grafted samples were basic and that based on NbMCM-41 exhibited much higher basicity than the APMS/MCM-41. The catalysts were studied in Michael addition between imidazole and ethyl acrylate for the production of N-alkyl imidazoles under sonic and non-sonic activation. The most important finding from this work is that the combination of amino-grafted NbMCM-41 with ultrasound conditions is a mild and effective method for the preparation of N-substituted imidazoles.