The hydrogen bond basicityβof ionic liquids, as demonstrated by the NMR studies and the Kamlet–Taft linear solvation energy relationship, was confirmed to be the dominant solvent descriptor determining the rate of the Knoevenagel condensation.

Two novel dicationic dimethyl phosphate ionic liquids have been designed as highly efficient solvents for the Knoevenagel condensation between ethyl cyanoacetate and aldehyde with a decreased reactivity -4-(dimethylamino)benzaldehyde. A simple synthetic strategy has been demonstrated for obtaining the dicationic dimethyl phosphate ionic liquid bearing both aromatic imidazolium and aliphatic ammonium moieties.