Nitration and oxidation of 4-methoxyphenol by nitrous acid in aqueous acid solution

Abstract

4-Methoxyphenol reacts with nitrous acid in aqueous acid solution to give a mixture of benzoquinone and 4-methoxy-2-nitrophenol. The effects on rates and product ratio of acidity, reactant concentrations, and the initial presence or absence of dissolved oxygen are reported. A mechanism is proposed in which nitric oxide and the 4-methoxyphenoxy radical are generated and the latter reacts with nitrogen dioxide or with water. Numerical integrations based on five inorganic and six organic reaction steps shows that the complete proposed mechanism accounts for all the observations.