Quaternary Vanado-Molybdotungstophosphoric Acid [H5PW6Mo4V2O40] Over Natural Montmorillonite as a Heterogeneous Catalyst for the Synthesis 4H-Pyran and Polyhydroquinoline Derivatives

Synthesis of an efficient and novel vanadium substituted molybdotungstophosphoric acid, H5PW6Mo4V2O40.14H(2)O (VMWP) supported on naturally occurring montmorillonite (nMont) clay by an incipient wetness impregnation technique. The support and resulting catalyst were characterized by Inductively coupled plasma atomic emission spectroscopy (ICP-AES), Fourier transform infrared (FT-IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Transmission electron microscopy (TEM) and thermogravimetric-Differential thermal analysis (TG-DTA). The study demonstrated that newly synthesized VMWP well incorporated on nMont with their good performance and activity. The catalytic application is evaluated in one-pot multicomponent synthesis of tetrahydrobenzo[b]pyrans (4H-Pyran) and polyhydroquinolines in excellent yield. High conversion, shorter reaction time, environmentally benign solvent simple experimental and work procedure and reusability of the catalyst are the prominent features of our synthetic route.