The introduction of two new imidazole-based bis-dicationic Bronsted acidic ionic liquids and comparison of their catalytic activity in the synthesis of barbituric acid derivatives

摘要

In this article, the preparation of bis-imidazolium hydrogen sulfate and bis-imidazolium perchlorate as two new bis-dicationic Bronsted acidic ionic liquids based on imidazole is reported. After characterization by FT-IR, mass and NMR spectroscopy and pH titration, the applicability of these reagents is studied in the promotion of the synthesis of 5-arylidene barbituric acids and pyrano[2,3-d] pyrimidinone derivatives. These methods possess some advantages such as ease of preparation of the catalyst, simple work-up procedure, short reaction times, excellent yields, and use of nonorganic solvents during all steps of the reactions and good reusability of the catalysts.