Kinetic and Mechanistic Study of Oxidation of Piperazines by Bromamine-T in Acidic Medium

• 作者: B. M. Venkatesha Chandrashekar Netkal M. Made Gowda S. Ananda
• 来源期刊: 催化剂现代研究(英文)
• 学科: 化学
• 关键词: PIPERAZINES OXIDATION KINETICS MECHANISM Bromamine-T BUFFER
• 年，卷（期）: 2013,（4）
• 页码范围: 157-163
• 页数: 7页
• 分类号: O6

摘要

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.