Department of Analytical Chemistry, L. Eötvös University , P.O. Box 32, H-1518 Budapest 112, Hungary.
J Phys Chem A. 2013 Sep 19;117(37):9023-7. doi: 10.1021/jp4071345. Epub 2013 Sep 5.
Oscillatory behavior is reported in the permanganate oxidation of glycine in the presence of Na2HPO4 in a stirred flow reactor. In near-neutral solutions, long-period sustained oscillations were recorded in the potential of a Pt electrode and in the light absorbance measured at λ = 418 and 545 nm, characteristic wavelengths for following the evolution of the intermediate [Mn(IV)] and reagent [MnO4(-) ] during the course of the reaction. No evidence of bistability was found. The chemical and physical backgrounds of the oscillatory phenomenon are discussed. In the oscillatory cycle, the positive feedback is attributed to the autocatalytic formation of a soluble Mn(IV) species, whereas the negative feedback arises from its removal from the solution in the form of solid MnO2. A simple model is suggested that qualitatively simulates the experimental observations in batch runs and the dynamics that appears in the flow system.
在搅拌流动反应器中，存在 Na2HPO4 时，草酸盐氧化中的振荡行为被报道。在近中性溶液中，在 Pt 电极的电势和在 λ = 418 和 545nm 处测量的光吸收率中记录到长周期持续振荡，这是在反应过程中跟踪中间物 [Mn(IV)] 和试剂 [MnO4(-)] 演变的特征波长。未发现双稳性的证据。讨论了振荡现象的化学和物理背景。在振荡循环中，正反馈归因于可溶性 Mn(IV)物种的自催化形成，而负反馈则源于其以 MnO2 固体的形式从溶液中除去。提出了一个简单的模型，该模型定性地模拟了分批运行中的实验观察结果以及流动系统中的动力学。
