Ruthenium(III) Catalyzed Oxidation of Aliphatic Primary Amines by Bromamine-T in Hydrochloric Acid Medium: A Kinetic Study

Abstract

The kinetics of the ruthenium(III) catalyzed oxidation of the aliphatic primary amines n-propylamine, n-butylamine and isoamylamine, by sodium N-bromo-p-toluenesulfonamide or bromamine-T (BAT) in HCl medium has been studied in the temperature range 298–313 K. The reaction rate shows a first-order dependence each on BAT, amine, and ruthenium(III). The reaction also shows an inverse fractional- and inverse first-order dependence on acid at low and high [HCl] ranges, respectively. Added halide ions and p-toluenesulfonamide (reduction product of BAT), and variation of ionic strength of the solvent medium have no effect on the rate. The activation parameters have been evaluated. Mechanisms consistent with the kinetic data have been proposed. The protonation constant of monobromamine-T has been evaluated to be 29 ± 2. A Taft LFE relationship is observed for the ruthenium(III) catalyzed reaction with ρ* = −4.6 indicating that the electron donating groups enhance the reaction rate. An isokinetic relationship is observed with β = 355 K indicating that enthalpy factors control the rate.