分光光度法分析高铁vi酸钾氧化胺类化合物的反应动力学及机理-analysis of reaction kinetics and mechanism of potassium ferrate vi oxidized amine compounds by spectrophotometry.docx

摘要本文通过分光光度法研究了碱性条件下高铁酸钾氧化胺类化合物的反应动力学及 机理。在离子强度不变的条件下，分别就还原剂浓度、碱度对反应体系表观速率常数 kobs 的影响进行了探讨，并求出了一系列温度下反应的速控步速率常数以及 298.2K 时反应 的活化参数，最后根据反应的宏观规律提出了可能的反应机理，由推得的速率方程计算 出的速率常数理论值与实验得到的实际值相一致，从而证明了所推机理的准确性。实验发现，在准一级反应条件下，高铁酸钾氧化胺类化合物的反应对还原剂为一级， 对 OH-为负分数级，表观速率常数随[OH-]的增大而减小，这说明在整个反应过程中存在 一个生成 OH-的前期平衡。同时，通过实验我们发现，高铁酸钾在碱性介质中的主要存 在形式是 FeO42-，其水解生成的 HFeO4-量很少，但是 HFeO4-却很容易与还原剂分子形 成中间络合物，利于反应的发生，因此，我们认为反应活性中心是 HFeO4-。通过实验历 程分析及机理推导得出的结论验证了这一理论。高铁酸钾是一种环境友好的高效消毒剂，在废水处理方面有很大潜力及发展前景， 本文通过研究高铁酸钾氧化胺类化合物的反应动力学，不仅为整个化学动力学领域的发 展提供了基础数据，为化学合成设计提供了理论依据，同时也为其在环境治理中的应用 提供了理论依据。关键词高铁酸钾正丁胺异丁胺1,3-丙二胺1,4-丁二胺异丙醇胺 异丁醇胺反应动力学及机理氧化还原反应AbstractIn this paper the kinetics of oxidation of amine compounds by potassium ferrate(VI) have been studied spectrophotometrically under alkaling condition. Throughout the experiments, optimal conditions for running the reaction were determined, the effects of reductant concentration, alkalinity and temperature on reaction rate (kobs) were summed up, from which the activation center was deduced, and a plausible reaction mechanism was put forward. The rate constants of the speed control step under different temperatures and the activation parameters at 298.2K were calculated. The theoretical value of rate constants fit the test value very well which proves the veracity of the mechanism.The results show first order dependence on potassium ferrate (VI) and on each reductant. The observed rate constant (kobs) decreases with the increase of [OH-], and the reaction rate has a negative fraction order with respect to [OH-], which indicates that there is a balance of [OH-] generation before the speed-control step. Meanwhile, we find that the main existed form of potassium ferrate is FeO42- in alkaline medium, and the concentration of HFeO4- is very small. However, it is easy for HFeO4- to form a six-membered ring complex with the reductant in the presence of a hydrogen atom. The formed complex has higher activity towards anion. Therefore, we consider the reaction takes place