Introduction of Agar-Entrapping as a Novel Strategy to Improve the Catalytic Activity of Moisture-Absorbing Acidic Ionic Liquids: A Case Study in the Synthesis of 5-Arylidene Barbituric Acids and Pyrano[2,3-d]Pyrimidinones

Abstract

In this article, to improve the detrimental character of ionic liquids, called moisture absorbing, agar-trapping is introduced as an affordable and straightforward protocol. Using inexpensive biopolymer, agar, as a trapper is a brilliant advantage of the method led to an environmentally sustainable development. Moreover, to show the effect of this method, the catalytic ability of a prepared agar-trapped acidic ionic liquid and its free form was experimentally compared in the synthesis of barbituric and thiobarbituric acid derivatives. In the presence of the entrapped catalyst and under the optimized conditions the products were obtained in high yields during short reactions time.

Keywords:

• DABCO-based ionic liquids
• agar-entrapped catalyst
• knoevenagel condensation
• pyrano[2,3-d]pyrimidineones

Acknowledgements

We are thankful to the Research Council of University of Guilan for the partial support of this research.