Abstract
Standard log
k
o
values for nitration are compared with previous partial rate factors. log
k
o
values for mono-substituted benzenes are correlated by σ
+
with ρ-9.7, but for polysubstituted derivatives and heterocyclic analogues much scatter is shown which is not improved by a correction term of type πσ
+
for substituent-substituent interactions. Comparison of relative reactivities of individual substrates towards nitration and to hydrogen exchange shows that there is no simple unique scale of substrate reactivity toward electrophilic substitution.