Abstract
Two‐parameter equation correlations are reported for radical reactions of aromatic compounds. In these correlations polar and resonance substituent constants identical with the substituent constants of aliphatic compounds were used. The equations correlate the rate constants for H abstraction reactions and for the addition of a variety of free radicals to the ortho‐, meta‐, and para‐substituted aromatic compounds. Besides, they correlate parameters of the spectra for substituted aromatic radicals. The correlations show that the effects of para substituents on the reactions studied are nearly entirely resonance effects, whereas for the meta‐ and ortho‐substituted compounds polar (inductive) effects become essential. Application of the two‐parameter correlations permits also to determine the structure of transition states (σ or π‐complex) in free‐radical reactions.