Sulfonic acid-functionalized magnetic nanoparticles as a recyclable and eco-friendly catalyst for atom economical Michael addition reactions and bis indolyl methane synthesis

Abstract

A modified sulfonic acid functionalized magnetic nanoparticle composite (Fe₃O₄@γFe₂O₃–SO₃H) is prepared by the use of ultrasonic irradiation. By this modification, the size of the nano-particles was reduced and the magnetization of the material was highly improved. This improvement drastically affected the efficiency and magnetic separation of the material as a catalyst. This new modified nanomagnetic compound was used as a highly efficient and recyclable catalyst for functionalization of indole derivatives via Michael addition and Friedel–Crafts alkylation reactions in entirely environmentally friendly media at room temperature. This modified magnetic material can be easily applied for large-scale operations producing the desired products in excellent yields in highly pure states.