Oxidation of substituted ethanols by sodium N ‐bromobenzenesulphonamide: A kinetic study

The kinetics of the oxidation of seven substituted ethanols by sodium N ‐bromobenzenesulphonamide or bromamine‐B (BAB) in the presence of HCl was studied at 45 °C. The rate shows a first‐order dependence on [BAB] 0 and is fractional in [alcohol] 0 , [H + ] and [Cl − ]. Ionic strength variations, addition of benzenesulphonamide reaction product and variation of dielectric constant of the medium have no effect on the rate. The solvent isotope effect k   H   2 O ′ / k   D   2 O ′≈ 0·97. The rates do not correlate satisfactorily with Taft's substituent constants. Activation parameters Δ H ≠ , Δ S ≠ , Δ G ≠ and log A were calculated by studying the reaction at different temperatures (308–323 K). It was found that Δ H ≠ and Δ S ≠ are linearly related and an isokinetic relationship is observed with isokinetic temperature β = 393 K, indicating enthalpy as a controlling factor.