Dicationic Ionic Liquid Modified Chitosan as a Sustainable Heterogeneous Catalyst for Knoevenagel Condensation Reactions

Ionic liquid (IL) grafted chitosan (CS) is fabricated in a feasible three-step process and used as a catalyst for the Knoevenagel condensation reaction. The IL modified CS (IL-CS) shows higher conversion/yield compared to pristine CS and Pyridine modified CS (Py-CS). The better efficiency of IL-CS can be ascribed to the synergistic effect of H-bonding groups (-OH of CS) and quaternary ammonium groups of ionic liquid. The material is very efficient in converting various functionalized aromatic aldehydes into their benzylidenemalononitrile derivatives. In addition, the catalyst exhibits retention of catalytic activity up to five cycles in the reusability study. The characterization of the recycled material clearly indicates the robust nature of IL-CS. Our work provides a feasible approach towards sustainable catalyst construction for industrially important reactions.