The immobilized Cu nanoparticles on magnetic montmorillonite (MMT@Fe3O4@Cu): As an efficient and reusable nanocatalyst for reduction and reductive-acetylation of nitroarenes with NaBH4

• Published in: Polyhedron 2020-01, Vol.175, p.114201, Article 114201
• Main Authors: Zeynizadeh, Behzad, Rahmani, Soleiman, Tizhoush, Hengameh
• Format: Article
• Language: English
• Subjects: Cu NPs; Montmorillonite K10; Nitroarenes; Reduction; Reductive-acetylation
• ISSN: 0277-5387
• DOI: 10.1016/j.poly.2019.114201

In this study, the immobilization of copper nanoparticles on superparamagnetic montmorillonite, MMT@Fe3O4@Cu, was studied. The prepared composite system was then characterized using FT-IR, SEM, EDX, XRD, VSM, BET and ICP-OES analyses. Next, catalytic activity of the Cu-clay system was studied towards feasible reduction of nitroarenes to anilines as well as reductive-acetylation of nitroarenes to acetanilides using NaBH4 and Ac2O in water as a green solvent. The utilized nanocatalyst can be easily separated from the reaction mixture by an external magnetic field and reused for six consecutive cycles without the significant loss of its catalytic activity. [Display omitted] In this study, the immobilization of copper nanoparticles on superparamagnetic montmorillonite, MMT@Fe3O4@Cu, was studied. Magnetically nanoparticles (MNPs) of iron oxide (Fe3O4) were primarily prepared by a chemical co-precipitation method. Next, the prepared Fe3O4 MNPs were intercalated within the interlamellar spaces and external surface of sodium-exchanged montmorillonite. Finally, Cu NPs were immobilized on magnetic montmorillonite by a simply mixing of an aqueous solution of CuCl2·2H2O with MMT@Fe3O4 followed by the reduction with NaBH4. Characterization of MMT@Fe3O4 clay system represented that through the immobilization of Fe3O4 MNPs, disordered-layers structure of MMT was easily reorganized to an ordered-layers arrangement. The synthesized composite systems were characterized using FT-IR, SEM, EDX, XRD, VSM, BET and ICP-OES analyses. SEM analysis exhibited that dispersion of Cu NPs, with the size distribution of 15–25 nm, on the surface of magnetic clay was taken place perfectly. BET surface analysis indicated that after the immobilization of Fe3O4 and Cu species, the surface area and total pore volume of MMT@Fe3O4@Cu system was decreased. Next, the Cu-clay nanocomposite system showed a perfect catalytic activity towards reduction of nitroarenes to anilines as well as reductive-acetylation of nitroarenes to acetanilides using NaBH4 and Ac2O in water as a green and economic solvent. The copper magnetic clay catalyst can be easily separated from the reaction mixture by an external magnetic field and reused for six consecutive cycles without the significant loss of its catalytic activity.