α-Zr(HPO4)2·H2O: As an effective and recoverable catalyst for the synthesis of a family of quinoxalines in semi-aqueous conditions

Abstract

In our work, we have established a straightforward and friendly process for the preparation of a family of quinoxaline. This method relies on using α-Zr(HPO4)2·H2O as a catalyst and an ethanol/water mixture as an ecological solvent. Firstly, we prepared α-Zr(HPO4)2·H2O by a simple hydrothermal procedure and conducted comprehensive characterization employing various analytical methods. On the other hand, we produced the quinoxalines by means of a condensation reaction between 1,2-dicarbonyl compounds and various 1,2-diamines. The synthesized quinoxaline and its derivative products were characterized by melting point, proton, and carbon nuclear magnetic resonance analysis. As a result, the optimal reaction conditions that resulted in a high yield (97–98 %) were an amount of catalyst of 0.03 g, a stirring time of 8 min, a volume of solvent of 2 mL, and a reaction temperature of 50 °C. This approach is advantageous due to its simple and eco-friendly procedure, green solvent, quick reaction time, low cost, and high yields. Additionally, it offers the possibility to recycle the catalyst for a minimum of five cycles with no decrease in its catalytic activity.