Silica Sulfuric Acid as a Reusable Catalyst for the Conversion of Ketones into Amides by a Schmidt Reaction under Solvent-Free Conditions

Silica sulfuric acid is a highly efficient reagent for the conversion of a variety of ketones into the corresponding amides by a Schmidt reaction under solvent-free conditions. Cyclic, aliphatic and aromatic ketones with electron-donating or withdrawing substituents may be converted easily in excellent yield. The major advantages of this method are: operational simplicity, the ready availability of the reagent, selectivity, general applicability, mild reaction conditions, short reaction times and high yields. The recovered catalyst could be used in new attempts without any purification.