Ultrasound-Mediated Synthesis of Novel α-Aminophosphonates Using Graphene Nanosheets-Silver Nanoparticles (GNS-AgNPs) as a Recyclable Heterogeneous Catalyst

A series of novel alpha-aminophosphonate derivatives were synthesized via simple and an efficient method from the three-component condensation reaction of 5-aminoindan or 3,4-(methylenedioxy)aniline, aromatic aldehydes and diethyl phosphite by employing graphene nanosheets-silver nanoparticles (GNS-AgNPs) as catalyst under ultrasonication and solvent-free condition. GNS-AgNPs was prepared in situ by simultaneous reduction of graphene oxide (GO) and silver nitrate (AgNO3) using sodium borohydride (NaBH4) as a reducing agent. The surface characterization of GNS-AgNPs was done using X-ray diffraction (XRD), Fourier transform infrared (FTIR), UV-Vis spectroscopy (UV-Vis), Thermogravimetric analysis (TGA), Raman spectroscopy and Field emission scanning electron microscopy (FE-SEM). The GNS-AgNPs are recyclable up to fifth run with minimal loss of its activity. Convenient operational simplicity, mild conditions, excellent yields of products, consistent performance and the reusability of catalyst makes this protocol feasible and attractive.