Preparation and characterization of Fe3O4@SiO2@PMA:AS an efficient and recyclable nanocatalyst for the synthesis of 1-amidoalkyl-2-naphthols

In this paper, we report a method for preparation of functionalized superparamagnetic Fe3O4@SiO2 that is synthesized based on several stages. First of all, the Fe3O4@SiO2 nanosphere core-shell is synthesized. Then, H3PMo12O40 nanoparticles were synthesized by the treatment of H3PMo12O40 with n-Octane as solvent by a solvothermal method and this nano hetero polyacid immobilized onto the imidazole functionalized Fe3O4@SiO2 nanoparticles. The structure of the samples was characterized by XRD, TEM, DLS, FE-SEM, FT-IR, N-2 adsorption-desorption isotherm analysis and VSM. Moreover, an efficient and direct protocol is described for the preparation of amidoalkyl naphthols employing a multi-component, one-pot condensation reaction of beta-naphthol, aldehydes and acetamide, benzamide and urea in the presence of Fe3O4@SiO2-imid-PMA(n) under solvent-free and microwave conditions. Also, nanocatalyst can be easily recovered by a magnetic field and reused for the next reactions for at least 5 times without distinct deterioration in catalytic activity. (C) 2014 Elsevier Ltd. All rights reserved.