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 PhCH 2 CD 2 OH ( 2 ) exhibited a substantial primary kinetic isotope effect ( k H / k D  = 5.83). The rates correlate satisfactorily with the Hammett free energy relationship. The activation parameters Δ H ≠ , Δ S ≠ , Δ G ≠ and log A were calculated for the reaction. The proposed mechanism is consistent with the observed results. Copyright © 2001 John Wiley & Sons, Ltd.