Iodination and iodo-compounds. Part II. The kinetics of aromatic iodination by means of the tri-iodine cation

Abstract

The reactions in sulphuric acid solutions between the tri-iodine cation and deactivated aromatic compounds follow second-order kinetics, first-order in each reagent. The rate of iodination varies with the concentration of water in the solvent and there is a moderately large kinetic isotope effect. The results are consistent with the occurrence of a two-stage reaction in which the loss of the proton is catalysed by the hydrogen sulphate ion.