The kinetics and mechanism of the electrophilic substitution of heteroaromatic compounds. Part XXXIX. Transmission of substituent effects in the pyridine system: Hammett-like treatment of hydrogenexchange data

Abstract

Hydrogen-exchange rate constants for pyridines and for benzenes are correlated by the same equation provided that interactions between substituents are allowed for by ΣΠσ⁺. The derived equation permits the calculation of rate constants for polysubstituted benzenes and pyridines with reactivities covering 17 log units; the significance of this equation as representing something more than an empirical relationship is however in considerable doubt.