Mechanism of aromatic iodination by iodine and nitric acid

Abstract

Kinetics of the iodination of a number of substituted benzenes by iodine and nitric acid in acetic acid solution have been studied. The reaction is catalysed by dinitrogen tetroxide and hydrogen ions and evidence is presented to show that the iodinating species is protonated NO₂I, which reacts in a slow step with the aromatic compound. Acidity function data for nitric acid in 10% aqueous acetic acid are presented and charge-transfer complex formation between iodine and m-xylene in acetic acid has been studied.