Chitosan as a reusable solid base catalyst for Knoevenagel condensation reaction

[Display omitted] •A series of Knoevenagel condensation products are obtained using chitosan as a solid base catalyst.•The reaction conditions are mild for this reaction.•The reaction is highly selective and clean, thus contributing to green and sustainable catalysis.•No side products are observed and hence the reaction is highly selective. In the present work, the commercially available chitosan is reported as a heterogeneous solid base catalyst for Knoevenagel condensation reaction of carbonyl compounds with malononitrile under mild reaction conditions. Chitosan is characterized by powder XRD, IR and elemental analysis. The catalytic activity of chitosan is evaluated in Knoevenagel condensation reaction of benzaldehyde and malononitrile as model substrates and the optimized reaction conditions are further used to expand its activity with various substrates. In addition, the catalyst stability is also examined by performing reusability, leaching experiments and it is observed that the catalyst can be reused for four times with no significant drop in its activity.