2,4-Dinitrobenzenesulfonic acid hydrate may be used in the synthesis of the corresponding α-hydroxyketone. It can be used as a catalyst in the amidation reaction, which involves the conversion of secondary-benzylic alcohols toN-benzylacetamides.It may also be used to prepare 1-octyl-2-pyrrolidinonium 2,4-dinitrobenzenesulfonate ([NOP][DNBSA]), a Brnsted-acidic ionic liquid, which can catalyze the synthesis of trioxane.