Kinetics of iodination of para-substituted phenols

Abstract

The correlation of log k for the iodination of para-substituted phenols with σ_m+aΔσ_p^– is much better than that with σ_m alone. Limited conjugation between substituent and oxygen in the activated complex has been suggested as the reason for this. The catalytic influence of various bases on the iodination velocity has been studied and the Brønsted coefficient is very small, ca. 0·2. The reaction of iodine with phenolate ion becomes rate-determining when the concentration of iodide ion is low.