Mechanistic studies of the oxidation of substituted phenethyl alcohols by N‐metallo‐N‐haloarylsulphonamides: kinetic isotope studies

The oxidation of para‐substituted phenethyl alcohols (PEA, 2) by N‐metallo‐N‐haloarylsulphonamides (1) in the presence of dilute HCl to the corresponding phenacetaldehydes (4) is first order with respect to oxidant (1) and [H+] and a fractional order each in [PEA] and [Cl−]. Addition of the reaction product (3), ionic strength variations and variation of dielectric constant of the medium had no effect on the rate. The oxidation of PhCH2CD2OH (2) exhibited a substantial primary kinetic isotope effect (kH/kD = 5.83). The rates correlate satisfactorily with the Hammett free energy relationship. The activation parameters ΔH≠, ΔS≠, ΔG≠ and logA were calculated for the reaction. The proposed mechanism is consistent with the observed results.