Application of Basic Ionic Liquid 1-Ethyl-3-methylimidazolium Diethylphosphatete Knoevenagel Reactions

Basic ionic liquid 1-ethyl-3-methylimidazolium diethylphosphate {+[(EtO)2(PO)O]-} was introduced as the catalyst for the Knoevenagel reaction of aldehydes with active methylene compounds.The catalytic activity of the ionic liquid was investigated with ethanol as the solvent and in the case without the presence of the solvent.The results show that the condensations of aromatic aldehydes proceed efficiently at room temperature with ethanol as the solvent to obtain the E-isomers in high yield(73.2%～97%) in the presence of 20% ionic liquid.At the solvent-free condition,the Knoevenagel reactions of aromatic aldehydes proceed smoothly(1～10 min) in the presence of 10% ionic liquid by mechanochemical grind.Comparing to the reations with ethanol as the solvent,these reactions can be carried out faster.Another feature of the methodology at the solvent-free condition is the condensation of aliphatic aldehydes with active methylene compounds,which is not easy to achieve by conventional reagents.The ionic liquid could be recycled five times and a yield of 85.9% of the last run was obtained.