【作者】 钱璟；

【导师】 单金缓；

【作者基本信息】 河北大学 ， 分析化学， 2004， 硕士

【摘要】 本文采用分光光度法研究了碱性介质中二过碘酸合镍（Ⅳ）配离子氧化α、β、γ位带有活性基团的二元醇类和醇胺类的动力学及机理。 关于四价镍配合物氧化有机化合物的研究，前人提出了以质子化程度高的[Ni（OH）₂（H₃IO₆）₂]^2-配离子形式存在，参与反应并进行电子转移的反应机理。本课题组探索了OH^-对反应体系的表观速率常数K_obs的影响，如果假设配离子是低质子的[Ni（OH）₂（H₂IO₆）₂]^4-，则1／K_obs对f（[OH^-]）／[OH^-]作图应有线性关系，和实验结果相符合；如果假设配离子是高质子的[Ni（OH）₂（H₃IO₆）₂]^2-，则1／K_obs对φ（[OH^-]）／[OH^-]作图是一条曲线，和实验结果不一致，基于理论计算和实验结果，我们提出了以质子化程度低的[Ni（OH）₂（HIO₆）]^2-作为活化中心与还原剂形成中间络合物，再进行内部电子转移的反应机理。 通过氧化二元醇类的研究发现：反应速率随被氧化基团的位置不同而改变，速控步的速率常数：α-丙二醇＞β-丁二醇＞γ-丁二醇。通过氧化二元醇和醇胺的比较发现：反应速率随被氧化基团性质的不同而改变，即氨基的反应速率要大于醇羟基的反应速率。二乙醇胺的反应速率大于四氢糠醇的反应速率。 通过假设提出的反应机理，能很好的解释实验现象，并求得了不同温度下的速控步的速率常数及25℃时的活化参数。以上体系的研究验证了配合物以低质子化的形式存在的假设更为合理，有力的否定了前人人为的存在形式。我们的探讨和研究会提供新的有价值的信息，为有机合成的路线设计和分析化学的定量分析提供一定的理论依据。更多还原

【Abstract】 The studies of oxidation of some simple organic compounds by Ni(IV) complex in previous works, which applied inprotonated complex [Ni(OH)2(H3IO6)2]2- as existed form to undergo electron transfer reaction.The kinetics and mechanism of oxidations of dihydric alcohols with a ?y-active group and a series of alcohol-amines by dihydroxydiperiodatonickelate(IV) in alkaline medium by the method of spectrophotometry were investigated. We also studied the influence of OH" on the constant of rate. If the deprotonated complex [Ni(OH)2(HIO6)]2- was presumed as the active species, the plot of l/kobs vs f([OH"])/[OH~] should be linear, which was in accordance with our experimental results. However, if the inprotonated complex [Ni(OH)2(H3lO6)2]2- was presumed as existed form, the plot of llkobs vs F([OH"])/[OH-] was a curve, which was not consistent with our experimental results.Based on calculated and experimental results, we proposed that the mechanism should be that the deprotonated complex was the active species, forming the intermediate adduct with the reductant and completing the reaction through electron transfer. Based on the studies of dihydric alcohols, we know that the reaction rate of the determining-step changed with the changing of the position of the oxidized group. The reaction rate of the determining-step have such a sequence: a -Propylene glycol>?Butylene-glycol >y-Butylene-glycol. Comparing dihydric alcohols with alcohol-amines, we find that the reaction rate of the determining-step changed with the changing of the oxidized group, namely, the rate of -NH3 is larger than that of -ROH. Comparing to previous work, we have a conclusion that the reaction rate changed with active-group, the observed rate constants of the rate-determining step of diethanolamine are larger than tetrahydrofurfuryl alcohol.The supposed mechanism could favorably explain the reaction results. Meanwhile, the rate constants (K) and activation parameters were obtained at different temperatures.The hypothesis that the complex was existed as the deprotonated form was supported by our experimental results. Our studies on this kind of system will provide us with more dynamical parameters, and provide theoretical foundation for the route design of the organic synthesis and quantitative analysis of analytical chemistry.更多还原