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

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