Selective nitration versus oxidative dealkylation of hydroquinone ethers with nitrogen dioxide

Article abstract of DOI:10.1016/S0040-4020(01)81329-6

Various alkyl-substituted p-dialkoxybenzenes (ArH) react readily with nitrogen dioxide (NO₂) in dichloromethane solution via either nitration (ArNO₂) or oxidative dealkylation to quinones (Q). Spectral transients indicate that these coupled processes proceed from the dialkoxybenzene radical cation (ArH⁺) formed as the common reactive intermediate from electron-transfer in the disproportionated precursor [ArH, NO⁺]NO₃^-. In fast subsequent steps, ArH⁺ undergoes homolytic coupling with NO₂ (which leads to aromatic nitration) and nucleophilic attack of NO₃- (which results in oxidative dealkylation). As such, the competition between nitration and oxidative dealkylation is effectively modulated by solvent polarity and added nitrate.