A highly effective synthesis of pyrimido[4,5-b]quinoline-tetraones using H3PW12O40/chitosan/NiCo2O4 as a novel magnetic nanocomposite

Abstract

In this research an efficient, robust, recoverable and magnetic nanocomposite, containing 12-phosphotungstic acid functionalized chitosan@NiCo2O4 NPs (PWA/CS/NiCo2O4), has been reported for the multi component reaction of aromatic aldehydes, 6-aminouracil or 6-amino-1,3-dimethyluracil with 2-hydroxy-1,4-naphthoquinone under reflux conditions. The present approach offers several advantages, such as simple procedure, green solvent, simple purification, excellent yield of products and short reaction times. In addition, the organic products were obtained easily, without the need of column chromatography, in good-to-excellent yields. The structure and characterization of the recoverable magnetically nanocatalyst, H3PW12O40/chitosan/NiCo2O4, have been done by using various spectroscopic techniques, which include Fourier transform infrared spectrophotometry (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX) and vibrating sample magnetometry (VSM) analysis methods. The obtained magnetic nanocomposite showed excellent catalytic activity as a new heterogeneous catalyst and can be separated from the reaction system with a simple external magnet. It is also confirmed that H3PW12O40/chitosan/NiCo2O4 could be reused without any significant loss in its activity.