Preparation of a novel, efficient, and recyclable magnetic catalyst,γ-Fe2O3@HAp-Ag nanoparticles, and a solvent- and halogen-free protocol for the synthesis of coumarin derivatives

摘要

In this protocol, Ag supported on the hydroxyapatite-core–shell magnetic γ-Fe_2O_3nanoparticles(γFe_2O_3@HAp-Ag NPs) as a novel, efficient, and magnetically recyclable catalyst is synthesized, and characterized by transmission electron microscopy(TEM), scanning electron microscopy(SEM), Fourier transform infrared spectroscopy(FT-IR), X-ray diffraction(XRD), and vibrating sample magnetometry(VSM). The use of the catalyst is described in the synthesis of coumarin derivatives by the Pechmann condensation of various phenols with β-ketoesters under solvent- and halogen-free conditions at 80℃.This novel and inexpensive method offers advantages, such as recyclability simple experimental protocol, short reaction time, minimal work-up procedure, and excellent yields of products, together with desirable, eco-friendly, green aspects by avoiding toxic elements and solvents, and ease of recovery from the reaction mixture using an external magnet.