Author(s)

Chandrashekar  , B. M. Venkatesha, S. Ananda, Netkal M. Made Gowda

Department of Chemistry, PES College of Engineering, Mandya, India.
Department of Chemistry, Western Illinois University, Macomb, USA.
Department of Chemistry, Yuvaraja’s College, University of Mysore, Mysore, India.
Department of Studies in Chemistry, Manasagangothri, University of Mysore, Mysore, India.

Oxidations of piperazine, 1-methylpiperazine and 1-ethylpiperazine by bromamine-T (BAT) in buffered acidic medium have been kinetically studied at 303 K. The reaction shows a first-order dependence of the rate each on [BAT]₀ and [piperazine]₀, and an inverse fractional-order dependence on [H⁺]. The additions of halide ions and the reduction product of BAT, p-toluenesulfonamide, have no effect on the reaction rate. The variation of ionic strength of the solvent medium has no influence on the rate. Activation parameters have been evaluated from the Arrhenius and Eyring plots. A common mechanism consistent with the kinetic data has been proposed for all piperazines. The protonation constants of substrates have been evaluated. The Hammett linear free-energy relationship has been observed for the reaction with ρ = ?0.5 indicating that the electron-donating groups enhance the reaction rate by stabilizing the transition state. An isokinetic relationship observed shows β = 368 K indicating the dominance of enthalpy factors on the reaction rate.

Piperazines; Oxidation Kinetics; Mechanism; Bromamine-T; Buffer

Chandrashekar, B. Venkatesha, S. Ananda and N. Gowda, "Kinetic and Mechanistic Study of Oxidation of Piperazines by Bromamine-T in Acidic Medium," Modern Research in Catalysis, Vol. 2 No. 4, 2013, pp. 157-163. doi: 10.4236/mrc.2013.24021.