Metal-Free Catalytic Oxidation of Urazoles under Mild and Heterogeneous Conditions via Combination of Ammonium Nitrate and Catalytic Amounts of Silica Sulfuric Acid

Highly efficient production of 4-substituted-1,2,4-triazole-3,5-diones from urazole derivatives using ammonium nitrate and silica sulfuric acid (SiO2-OSO3H), as a cheap and nontoxic catalyst, in the presence of wet SiO2 (50% w/w) under mild and heterogeneous conditions is reported. The process presented here is operationally simple, environmentally benign and produces high yield.