Zirconium(IV)-modified silica@magnetic nanocomposites: Fabrication, characterization and application as efficient, selective and reusable nanocatalysts for Friedel-Crafts, Knoevenagel and Pechmann condensation reactions

A highly efficient and magnetically retrievable zirconium(IV) based nanocatalyst has been synthesized by covalent grafting of 3-hydroxy-2-methyl-1,4-naphthoquinone onto amine functionalized silica coated magnetic nanoparticles followed by complexation with ZrOCl2. The structural and magnetic properties of obtained nanocatalyst are identified by TEM, SEM, XRD, EDS, VSM and FT-IR analyses. The potential of resultant organic-inorganic hybrid nanocatalyst was effectively evaluated for the range of organic transformations such as Friedel-Crafts, Knoevenagel and Pechmann condensation reactions. The magnetically recoverable nano-hybrid catalyst presented high TON and chemoselectivity with the ease of reusability for multiple cycles without any appreciable loss in its catalytic activity. (C) 2013 Elsevier B.V. All rights reserved.