The Efficient Knoevenagel Condensation Promoted by Bifunctional Heterogenized Catalyst Based Chitosan-EDTA at Room Temperature

An efficient heterogeneous catalyst-based low molecular weight chitosan (LWC) modified with EDTA groups were prepared and applied as a bifunctional heterogenized catalyst in the Knoevenagel Condensation reaction, promoting fast reactions between malononitrile and aldehydes or isatins at room temperature. Chitosan-EDTA (LWC-EDTA) catalysts were characterized by Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA/DTA), powder X-ray diffraction (XRD). UV–Vis absorption spectrophotometry showed that the functionalization of chitosan with EDTA for 72 h promotes the most significant modification of the matrix surface compared to the others applied, reflecting shorter reaction times. The reactions using the LWC-EDTA-72 catalyst present excellent isolated yields (78–98%) in short reaction times (0.50–120 min) for differents Knoevenagel compounds. Additionaly, the catalyst was easily recovered and reused up to six times without significant losses of its catalytic activity. Graphical Abstract