Electrophilic aromatic substitution. Part XIV. Kinetics of nitration of some aromatic sulphonic acids in sulphuric acid

Abstract

Rates of nitration in sulphuric acid of the acids Ph[CH₂]_n·SO₃H (n= 0–3) have been measured. The acids react as their anions. Even in the case n= 3, the sulphonate group exerts a deactivating influence. The proportions of isomers formed from benzenesulphonic acid vary with acidity, and at high acidities a small proportion of the nitration may involve the un-ionised acid. Methyl phenyl sulphone is nitrated as the free base, but at high acidities both the rate of reaction and the change in isomer proportions suggest that hydrogen bonding may be occurring.