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

Mohammad Zolfigol,Ezat Ghaemi,Elahe Madrakian

doi:10.3390/71000734

Abstract

Nitrophenols can be obtained in moderate to high yields via nitrosation-oxidation 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.

Highlights

In several industrially important processes a large excess of sulfuric acid is required because the water by-product slows the reaction down by diluting the acid
In continuation of our studies on the application of inorganic acidic salts we found that silica gel reacts with chlorosulfonic acid to give silica sulfuric acid (I)
We were interested in using this inorganic acidic resin (I) as a new sulfuric acid function immobilized on the surface of silica gel via covalent bonding for the insitu generation of HNO2 when used in conjunction with NaNO2, wet SiO2

Summary

Introduction

In several industrially important processes (e.g. nitration, nitrosation, etc.) a large excess of sulfuric acid is required because the water by-product slows the reaction down by diluting the acid. We were interested in using this inorganic acidic resin (I) as a new sulfuric acid function immobilized on the surface of silica gel via covalent bonding for the insitu generation of HNO2 when used in conjunction with NaNO2, wet SiO2.

Results

Conclusion