Silica Sulfuric Acid/NaNO₂ as a Novel Heterogeneous System for the Oxidation of Urazoles Under Mild Conditions

Abstract

Neat chlorosulfonic acid reacted with silica gel to give silica sulfuric acid (I) in which sulfuric acid functions immobilized on the surface of silica gel via covalent bonding. Urazoles and bis-urazoles can be readily converted to their corresponding triazolinediones with a combination of silica sulfuric acid (I), wet SiO₂ and sodium nitrite in dichloromethane at room temperature.

Keywords:

• Silica sulfuric acid
• Urazoles
• Triazolinediones
• Oxida-tion
• Heterogeneous conditions

Acknowledgment

Financial support for this work by the research affairs of Bu-Ali Sina University, Hamadan, Iran.