Kinetics and mechanism of chlorination of toluene and some substituted toluenes by chloramine‐T

The kinetics of chlorination of toluene, o ‐methyl toluene, p ‐methyl toluene, m ‐methyl toluene, and m ‐chlorotoluene by chloramine‐T(CAT) in aqueous acetic acid in the presence of HClO 4 have been studied. The reaction is first order with respect to [CAT] as well as [H + ]. The order with respect to the substrate is unity in the case of toluene and m ‐chlorotoluene, fractional in the case of o ‐methyl toluene and p ‐methyl toluene, and zero order in the case of m ‐methyl toluene. Nuclear halogenation has been observed with m ‐methyl toluene, while nuclear and side‐chain halogenation for p ‐methyl toluene and o ‐methyl toluene, and sidechain halogenation for toluene and m ‐chlorotoluene are the pathways. An increase in the proportion of acetic acid accelerates the rate. Added acetate ions inhibit the reaction, and added p ‐toluene sulfonamide causes a pronounced retardation. A mechanism involving AcO + HCl as the important electrophile is discussed.