Synthesis of arylidinebarbituric acid derivatives catalyzed by dodecylbenzenesulfonic acid (DBSA) in aqueous media

A series of arylidine barbituric acid derivatives was synthesized by Knoevenagel condensation reaction of aromatic aldehydes with barbituric acid or thiobarbituric acid using dodecylbenzenesulfonic acid as a Brønsted acid-surfactant catalyst in aqueous media. Regardless of the nature of the substitution (electron-donating and -withdrawing), all the reactions were completed within 15-65 min in water at reflux condition. In these reactions, there was no need for the column purification of the products. The present methodology offers several advantages such as excellent yields, simple procedure and work-up steps, short reaction times, as well as inexpensive and non-toxic catalyst. Use of water as the reaction medium makes the process environmentally benign.