Silanization of Iron Oxide Magnetic Nanoparticles with ionic liquids based on amino acids and its application as heterogeneous catalysts for Knoevenagel condensation reactions

Isabel del Hierro, Yolanda Pérez, Mariano Fajardo

Index: 10.1016/j.mcat.2018.03.008

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Abstract

Iron oxide magnetic nanoparticles (MNPs) stabilized with silane ligands, containing choline hydroxide and amino acid ionic liquid functionalities, have been prepared. The appropriate silane ligands have been synthesized; the choline hydroxide propyl silane ligand in a process inspired in the industrial production of choline hydroxide and the amino acid ionic liquids in a straight forward acid-base process using the former compound. The synthesized materials have been fully characterized by elemental analysis, X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), UV–vis diffuse reflectance spectroscopy (DRUV-vis), thermogravimetric analysis (TG-DTG), N2 adsorption-desorption, transmission electron microscopy (TEM) and voltammetry solid state techniques. Ionic liquid stabilized magnetic nanoparticles have been very effective as heterogeneous basic catalysts in Knoevenagel condensation reaction at room temperature. The catalyst containing choline hydroxide ionic liquid (Chol-MNPs) exhibited highest catalytic activity and can easily be recovered under an external magnetic field and subsequently reused several times.