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

• Preparation of the magnetic nanocatalyst.
• Immobilization of PMA nanoparticles on imidazole functionalized Fe3O4@SiO2.
• Identification of catalyst by XRD, TEM, DLS, FE-SEM, FT-IR, BET and VSM.
• Catalyst recycling by external magnetic field.
• The preparation of 1-amidoalkyl-2-naphthols as biologically compounds.

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, N2 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 β-naphthol, aldehydes and acetamide, benzamide and urea in the presence of Fe3O4@SiO2-imid-PMAn 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.

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