Selective nitration of phenol over silicotungstic acid supported zirconia

Nitration of phenol was carried out using silicotungstic acid supported on hydrous zirconia as catalyst with stoichiometric quantities of nitric acid and phenol in dichloroethane medium at room temperature. The reaction proceeds through the formation of nitronium ion, which attack the phenol ring preferential at ortho position in presence of silicotungstic acid supported zirconia, forming mononitrophenol. Compared to the conventional process, phenol nitration over solid acid catalyst such as silicotungstic acid supported zirconia is a clean and environmental friendly process.