Zn(ii) anchored onto the magnetic natural hydroxyapatite (ZnII/HAP/Fe3O4): as a novel, green and recyclable catalyst for A3-coupling reaction towards propargylamine synthesis under solvent-free conditions

Abstract

In this paper, Zn(II) anchored onto the magnetic natural hydroxyapatite (Zn^II/HAP/Fe₃O₄), as a new, versatile and magnetically recoverable catalyst, was prepared and characterized using different techniques such as FT-IR, XRD, TGA, TEM, EDX, VSM and ICP. The composition of this catalyst was determined and it was clearly found that the size of the particles was about 8–30 nm and they were rod-like in shape. Also, VSM analysis showed that the synthesized nanocatalyst had superparamagnetic behavior. The new nanocatalyst has been found to effectively catalyze the synthesis of structurally different propargylamine derivatives via a one-pot three-component A³-coupling reaction of terminal alkynes, aldehydes and secondary amines in high yields at 100 °C under solvent-free conditions. This green protocol provides significant advantages, such as excellent yield of products, broad substrate scope, mild reaction conditions, minimization of chemical waste, simple work-up procedure, easy preparation of catalyst and being environmentally benign. Importantly, the prepared nanocatalyst can be recovered by applying an external magnetic field and reused for seven cycles without significant loss of activity.