Alum catalyzed simple and efficient synthesis of 5-arylidene-2,4-thiazolidinedione in aqueous media

Alum (KAl(SO4)(2)center dot 12H(2)O) is an inexpensive, efficient, and non-toxic catalyst used for the synthesis of 5-arylidine-2,4-thiazolidinediones by the Knoevenagel condensation of aromatic aldehydes with 2,4-thiazolidinedione in aqueous media at 90 degrees C. This method affords the 5-arylidine-2,4-thiazolidinediones in short reaction times, high yields, and green aspects by avoiding toxic catalysts and hazardous solvents.