Preparation and Characterization of a Novel Glycine-based Ionic Liquid and its Application in the Synthesis of Xanthenediones and Dihydropyrimidones in Water

Aim and Objective: A novel amino acid ionic liquid was synthesized, characterized, and approved as an efficient and recyclable catalyst for synthesizing xanthenediones and DHPMs in water at reflux temperature. Materials and Methods: The ionic liquid was synthesized by a two-step method. In the first step, pyridine- N-sulfonic acid was prepared by the reaction of pyridine with chlorosulfonic acid. In the second step, the reaction of as-prepared ionic liquid with glycine in water afforded the desired amino acid ionic liquid. Then, the ionic liquid was fully characterized by FT-IR, ¹H NMR, ¹³C NMR, MS, TG/DTG, and Hammett acidity function. Results: We disclose a new strategy to incorporate glycine as the amino acid-based cation in the ionic liquid structure. The prepared IL exhibited remarkable catalytic activity in synthesizing xanthendiones and DHPMs in water at reflux temperature. Conclusion: We have developed a green and efficient amino acid ionic liquid to synthesize xanthenediones in water at reflux temperature. The advantage of this protocol is highlighted by the novelty of the ionic liquid, using H2O as the solvent, simple work-up, high yields, and short reaction times.