Field and charge-transfer theory for the quantitative correlation of substituent effects in aromatic molecules. Part III. Thermal heterolytic addition and elimination reactions of substituted benzenes

Expressions, based on simple reaction models, for the effects of substituents on the equilibrium constants and rate constants of the reactions mentioned in the title are derived. Conditions under which ρσ relationships should be valid are established. Various theoretical σ and ρ scales are evaluated and are shown to be in good agreement with empirical scales when they ought to be. The calculations of all of the theoretical scales involve only one measured value of a substituent effect on a reaction.