Fe3O4@chitosan‐bound picolinaldehyde Cu complex as the magnetically reusable nanocatalyst for adjustable oxidation of sulfides

Abstract

As ecological and environmental demands for sustainability are one of the most strategic landscapes in the green chemistry, recent chemical researches have been directed toward eco‐friendly catalysts. Further advancement in this area has presented magnetically recoverable nanocatalyst. Herein, Cu‐based nanocatalyst was synthesized via reaction of picolinaldehyde and amine group of immobilized chitosan on the magnetic nanosupport, and followed by metallation. The prepared nanocatalyst was characterized by a variety of techniques. FT‐IR analysis demonstrated the favored coating of chitosan‐based Cu complex over Fe3O4 nanoparticles. The scanning electron microscopy and transmission electron microscope techniques confirmed nano‐sized of the catalyst. Fe3O4 nanoparticles and the nanocatalyst fit the X‐ray diffraction pattern of standard magnetite. High thermal stability of the nanocatalyst was determined by the TGA analysis. The inductively coupled plasma atomic emission analysis technique specified content of Cu was 0.62 mmol/g. Magnetic properties were analyzed by the vibrating sample magnetometer study. Regarding green chemistry goals, the applicability of this nanocatalyst was tested in the oxidation of sulfides derivatives. The nanocatalyst exhibited high catalytic activity and selectivity in the oxidation of sulfides to the corresponding sulfoxide (without over‐oxidation of sulfides to sulfones) under green conditions. Based on the magnetic properties (alluded to the Fe3O4 component), the nanocatalyst could be easily recovered from the reaction mixture using an external magnet, and reused up to four times without noticeable deterioration in its performance. Moreover, the other merits such as high yields, mild reaction condition, use of stable and green oxidant and eco‐friendly procedure made this nanocatalyst as a valuable catalyst in practical synthesis. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1626–1631, 2018