Aromatic sulfonation XII: Kinetics of the sulfonation of p‐ and o‐toluenesulfonic acid in aqueous and fuming sulfuric acid

Abstract The kinetics of the sulfonation of p ‐ and o ‐toluenesulfonic acid have been measured at 25.0° in aqueous and fuming sulfuric acid, the concentrations varying from 93.3‐103.3 wt‐% H 2 SO 4 . The reaction is first order with respect to the sulfonic acid. The observed variation in the apparent first order rate constants is of the order of 10 6 . The sulfonation kinetics are shown to be consistent with the sulfonation mechanisms previously proposed for aqueous 1 and fuming 2 sulfuric acid. In aqueous sulfuric acid varying in composition from 93.3‐98.8 wt‐% H 2 SO 4 isomerization was shown to be a reaction of minor importance.