Synthesis and characterization of a novel and green rod‐like magnetic ZnS/CuFe<sub>2</sub>O<sub>4</sub>/agar organometallic hybrid catalyst for the synthesis of biologically‐active 2‐amino‐tetrahydro‐4<i>H</i>‐chromene‐3‐carbonitrile derivatives
Shahrzad Bahrami, Fereshte Hassanzadeh‐Afruzi, Ali Maleki
Abstract
The magnetic biocompatible rod‐like ZnS/CuFe 2 O 4 /agar organometallic hybrid catalyst was designed and prepared based on a natural macromolecule (agar) through a green and convenient method using inexpensive, nontoxic, and easily available substances. Then, the as‐prepared catalyst was characterized by several techniques such as Fourier transform‐infrared spectroscopy, energy‐dispersive X‐ray analysis, scanning electron microscopy image, transmission electron microscopy, vibrating sample magnetometry curve, X‐ray diffraction pattern, and thermogravimetric analysis. Eventually, the catalytic application of the ZnS/CuFe 2 O 4 /agar nanobiocomposite was assessed in sequential Knoevenagel condensation–Michael addition reaction of dimedone, malononitrile, and different substituted aromatic aldehydes for the synthesis of 2‐amino‐tetrahydro‐4 H ‐chromene‐3‐carbonitrile derivatives. Some notable strengths of this environmentally benign catalyst include simplicity of catalyst preparation and separation, affording desired products with satisfactory yields (81%–97%) in very short reaction times (3–18 min), and with no need for complicated work‐up processes. Experimental tests showed that the catalyst can be successfully reused after five sequential runs without significant reduction in its catalytic efficiency.