Green synthesis of novel 5-amino-bispyrazole-4-carbonitriles using a recyclable FeO@SiO@vanillin@thioglycolic acid nano-catalyst.

Bis(thioglycolic acid)-vanillin (2,2'-(((4-hydroxy-3-methoxyphenyl)methylene)bis(sulfanediyl))diacetic acid)-functionalized silica-coated FeO magnetic nanoparticles (FeO@SiO@vanillin@thioglycolic acid MNPs) were synthesized and characterized by transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis/differential thermogravimetry (TGA-DTG), X-ray powder diffraction (XRD), X-ray spectroscopy (EDX), vibrating sample magnetometry (VSM), zeta potential measurements and Fourier transform infrared spectroscopy (FT-IR). The ensuing MNPs offer an environmentally friendly procedure for the synthesis of novel 5-amino-pyrazole-4-carbonitriles a three-component mechanochemical reaction of synthesized azo-linked aldehydes or synthesized pyrazolecarbaldehydes, malononitrile, and phenylhydrazine or -tolylhydrazine adhering to the green chemistry principles; products were generated expeditiously in high yields. The catalyst could be quickly recovered and reused for six cycles with almost consistent activity.