Relative reactivity and kinetic pattern of aniline and N‐methylaniline as nucleophiles in aromatic substitution (SNAr) reactions

Kinetic results are reported for the reactions of 4‐nitrophenyl‐2,4,6‐trinitrophenyl ether 3 with aniline and N ‐methylaniline in dimethyl sulphoxide, acetonitrile, methanol, and benzene. The reactions gave the expected 2,4,6‐trinitrodiphenylamine and were base catalyzed in all the solvents. Both nucleophiles showed the same kinetic pattern under the same reaction conditions but aniline was found to be considerably more reactive than N ‐methylaniline. The greater catalytic efficiency of aniline over N ‐methylaniline is consistent with the proton transfer mechanism of the base‐catalyzed step. Dichotomy of amine effects in aromatic substitution (S N Ar) reactions is discussed.