Imidazolium-Based Phosphinite Ionic Liquid (IL-OPPh₂) as Reusable Catalyst and Solvent for the Knoevenagel Condensation Reaction

Abstract

A task-specific ionic liquid (IL, OPPh₂) that bears a phosphinite weak Lewis base group in an imidazolium cation was found to efficiently catalyze the Knoevenagel condensation of arylaldehydes with malononitrile, dimethyl(diethyl)malonate, and ethyl cyanoacetate. This IL plays a dual role as both the reaction media and also catalyst, and it can be easily recovered and reused in several runs. Satisfactory results were obtained with good yields, short reaction time, and simplicity in the experimental procedure. A variety of coumarin derivatives were synthesized in this procedure.

Keywords:

• Coumarin
• ionic liquid
• Knoevenagel
• task-specific

ACKNOWLEDGMENT

The partial financial assistance from the research vice chancellor of Azarbaijan University of Tarbiat Moallem is gratefully acknowledged.

Notes

^a 10 mmol benzaldehyde or salicylaldehyde and 12 mmol diethylmalonate, 60 °C.

^a 10 mmol benzaldehyde or salicylaldehyde, 12 mmol active methylene compound, and 1 mmol TSIL, 60 °C.

^a The reaction was conducted at 60 °C.

^b Yield of isolated product.

^a The reaction was conducted at 60 °C.

^b Yield of isolated product.