Cationic lignin as an efficient and sustainable homogenous catalyst for aqueous Knoevenagel condensation reactions.

Knoevenagel condensation is a chemical reaction between aldehydes and active methylene-containing compounds in the presence of heterogeneous, basic homogenous organic or inorganic catalysts and solvent or neat systems. Herein, we introduced a new strategy for this synthesis by using the aqueous solution of cationic kraft lignin (CKL) as a catalyst. The CKL was synthesized through the reaction of kraft lignin (KL) with glycidyltrimethylammonium chloride (GTMAC) in a basic medium.