An efficient synthesis of 5-arylidine 2,4-thiazolidinediones by the Knoevenagel condensation of aromatic aldehydes with 2,4-thiazolidinedione using 1-benzyl-3-methylimidazolium dihydrogen phosphate ([bnmim]H2PO4) acidic ionic liquid at 70°C. This method gives remarkable advantages such as simple procedure, reactions at mild condition, much faster (50-90 min) reactions, excellent yield of products and the ionic liquid was successfully reused for four cycles without significant loss of activity.
