Silica Sulfuric Acid/ NaNO2 as a Novel Heterogeneous System for the Nitration of Phenols under Mild Conditions

Nitrophenols can be obtained in moderate to high yields via nitrosationoxidation of phenols with silica sulfuric acid, NaNO2 and wet SiO2 at room temperature. In situ generation of HNO2 and a radical cation mechanism via the nitrous acid catalyzed (NAC) pathway appear to be applicable to phenol nitration using these reagents.