Known as a Lewis acid which acts as a natural catalyst, bentonite can be used to produce several arylidene  (thio) barbituric  acid  derivatives  through  conducting  a  Knoevenagel  reaction  between aromatic aldehydes and (thio) barbituric acid. Water is considered as the medium for this reaction and the results are at arange of good to excellent over a reasonable reaction time. This method i...