Chlorination of arylammonium salts in sulphuric acid
Aromatic amines (aniline, o-toluidine, and p-toluidine) were dissolved in concentrated sulphuric acid and chlorinated with chlorine gas. At room temperature, chlorination was very selective, occurring ortho or para to the methyl group. In the absence of an activating methyl group, chlorination was slow. Dichlorination did not occur. For comparison, the amine–aluminium chloride–hydrogen chloride complexes were chlorinated.