Kinetic and mechanistic studies on the oxidation of pyrrolidine by bis(hydrogenperiodato)argentate(III) complex anion
作者:Jiong Zhang、Shuying Huo、Hongmei Shi、Shigang Shen、Yanli Shang
DOI:10.1007/s11243-012-9655-7
日期:2013.2
The kinetics of oxidation of pyrrolidine by bis(hydrogenperiodato)argentate(III) complex anion ([Ag(HIO6)2]5−) was studied in alkaline medium, with reaction temperatures in the range of 15.0–30.0 °C. The experiments indicated that the oxidation follows an overall second-order reaction, being first-order in both Ag(III) and pyrrolidine. The observed second-order rate constants, k′, decreased with increasing [IO4 −] but increased slightly with increasing [OH−]. The influence of ionic strength on the reaction rate was also investigated. The oxidation resulted in oxidative deamination of pyrrolidine, giving 4-hydroxybutyrate as the product. A reaction mechanism is proposed which includes an equilibrium between [Ag(HIO6)2]5− and [Ag(HIO6)2(OH)(H2O)]2−; these two Ag(III) species are reduced by pyrrolidine in parallel rate-determining steps. The rate equation derived from the proposed mechanism can explain the experimental observations. The rate constants of the rate-determining steps, together with the associated activation parameters, were calculated accordingly.
在碱性介质中研究了双(氢高碘酸)银(III)络合物阴离子 ([Ag(HIO6)2]5−) 氧化吡咯烷的动力学,反应温度在 15.0–30.0 °C 范围内。实验表明,氧化遵循整体二级反应,在 Ag(III) 和吡咯烷中均为一级反应。观察到的二阶速率常数 k' 随着 [IO4 -] 的增加而减小,但随着 [OH-] 的增加而略有增加。还研究了离子强度对反应速率的影响。氧化导致吡咯烷氧化脱氨,得到4-羟基丁酸酯产物。提出了一种反应机制,其中包括 [Ag(HIO6)2]5− 和 [Ag(HIO6)2(OH)(H2O)]2− 之间的平衡;这两种 Ag(III) 物质在平行的速率决定步骤中被吡咯烷还原。从所提出的机制导出的速率方程可以解释实验观察结果。相应地计算速率决定步骤的速率常数以及相关的激活参数。