Tungstophosphoric Acid Supported on Zirconia: A Recyclable Catalyst for the Green Synthesis on Quinoxaline Derivatives under Solvent-Free Conditions

Abstract

A green, simple, and fast procedure has been developed for the preparation of quinoxaline derivatives by a condensation of 1,2-diamines with 1,2-dicarbonyl compounds in the presence of zirconium oxide modified with tungstophosphoric acid (H₃PW₁₂O₄₀) as a heterogeneous catalyst, in a solvent-free medium using conventional heating. Quinoxaline derivatives were formed in short-time periods and excellent yields (65–100%). The reaction work-up is very simple and the catalyst can be easily separated from the reaction mixture and reused several times in subsequent reactions without appreciable loss of the catalytic activity.

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GRAPHICAL ABSTRACT

Keywords:

• Quinoxalines
• tungstophosphoric acid
• mesoporous zirconia
• ecofriendly process
• solvent-free condition

Acknowledgments

The authors thank L. Osiglio and G. Valle for their experimental contribution and CONICET, ANPCyT, and National University of La Plata for the financial support. Luis R. Pizzio, Mirta N. Blanco, and Gustavo P. Romanelli are members of CONICET.