ZnFe₂O₄@dimethylglyoxime: preparation and catalyst application in the synthesis of 2-amino-tetrahydro-4H-chromene-3-carbonitrile derivatives

Hybrid materials constructed from two or more constituents provide new features and distinctive application which is not found in the single-part material. Spinel ferrites with general formula of AB₂O₄, where A and B represent a divalent metal ion (such as Zn(II), Ni(II), Cu(II),) and Fe(III) ions, appeared as efficient catalysts for the synthesis of organic compound. These magnetic nanoparticles have both the Lewis acid and the Lewis base sites in their structure. In present study, the ZnFe₂O₄ ferrite was prepared and modified with dimethylglyoxime to obtain magnetic ZnFe₂O₄@dimethylglyoxime hybrid catalyst. Dimethylglyoxime, N,N′-dihydroxy-2,3-utanediimine, is a dibasic acid substance which has been used as a chelating agent for divalent metal ions due to containing two nitrogen atoms and hydroxyl groups. Surface modification zinc ferrite with this dibasic acid substance produced bifunctional hybrid catalyst with increased active sites. In next step, prepared catalyst was applied in the synthesis of 2-amino-tetrahydro-4H-chromene-3-carbonitrile derivatives by condensation of dimedone, aromatic aldehydes and malononitrile in ethanol at room temperature. The present procedure offers some advantages such as simple procedure, mild reaction condition, short reaction times and retrievablity catalyst.