Green Method Synthesis of Magnetic Nanoparticles and its Functionalized MNPs for Knoevenagel Condensation Reaction

Knoevenagel condensation is an important C-C bond formation reaction catalyzed by various homogeneous and heterogeneous acid-base catalysts. Knoevenagel condensation is an important C-C bond formation reaction, and employs various acid and base-catalyzed reactions of both homogeneous and heterogeneous catalysts. The present work describes the eco-friendly preparation of magnetic nanoparticles Fe3O4 (MNPs) and its functionalization to Fe3O4@SiO2@SO3H. The prepared MNPs and their functionalized materials were fully characterized by FT-IR, XRD, FE-SEM, HR-TEM, and VSM. Further demonstrated application of these catalysts for the C-C bond formation reactions of Knoevenagel condensation employing special aldehyde derivatives with malononitrile at room temperature gave excellent product isolation. The application of the prepared functionalized MNPs for the Knoevenagel condensation was demonstrated by the reaction of various aryl/heterocyclic and cholesterol aldehyde with malononitrile at room temperature stirring for about 30 min in ethanol solvent. The final product isolated is confirmed by various spectroscopic techniques such as FT-IR, 1H-, & 13C-NMR, and mass spectrometry. Furthermore, the selected compounds are screened for their photophysical properties, and interestingly compound 3j showed good fluorescent properties. Overall the present work described a greener method preparation of MNPs, and its functionalized employed as a heterogeneous catalyst for the Knoevenagel condensation of various aryl/heterocyclic and cholesterol aldehyde with malononitrile. The method developed is simple, easily separated catalyst by an external magnet, and recycled up to five cycles without any noticeable change in the final product isolation. Further, the prepared derivatives screened for their photophysical properties, and interestingly compound 3j showed good fluorescent properties.