【作者】 刘红梅；

【导师】 翟永清；

【作者基本信息】 河北大学 ， 无机化学， 2008， 硕士

【摘要】 本文采用分光光度法和氧化还原滴定法分别研究了酸性介质中过渡金属离子催化Ce(Ⅳ)氧化某些有机物的反应动力学,并用化学方法、红外光谱等多种现代分析手段鉴定、表征了氧化产物；通过对氧化产物及动力学数据的分析,推导出了相应的反应机理。在酸性介质中用分光光度法研究了铈(Ⅳ)离子在痕量钌(Ⅲ)离子催化作用下,于298-313K区间氧化四氢糠醇(THFA)的反应动力学。结果表明反应对铈(Ⅳ)离子为一级,对THFA和钌(Ⅲ)离子均为正分数级。准一级反应速率常数κobs随[HSO4-]增加而减小。在氮气保护下,反应能引发自由基聚合,反应中有自由基产生。在酸性介质中用氧化还原滴定法研究了铈(Ⅳ)离子在痕量钌(Ⅲ)离子催化作用下,于288-303K区间氧化1,2-丙二醇(PRD)的反应动力学。结果表明反应对铈(Ⅳ)离子为零级,对钌(Ⅲ)离子为一级,对PRD为负分数级。速率常数κobs随[H+]的增大而增大。反应中没有自由基产生。在酸性介质中用氧化还原滴定法研究了铈(Ⅳ)离子在痕量钌(Ⅲ)离子催化作用下,于298-313K区间氧化异丙醇(IPA)的反应动力学。结果表明反应对铈(Ⅳ)离子和钌(Ⅲ)离子均为一级,对IPA为零级。准一级反应速率常数κobs随[HSO4-]增加而减小,随[H+]的增大而增大。反应中没有自由基产生。在酸性介质中用氧化还原滴定法研究了铈(Ⅳ)离子在痕量铱(Ⅲ)离子催化作用下,于298～313K区间氧化乙醇胺的反应动力学。结果表明,反应对铈(Ⅳ)离子为一级,对铱(Ⅲ)离子也是一级,对乙醇胺(EAN)的反应级数为正分数级。准一级速率常数κobs,随[H+]和[HSO4-]增加而减小,反应中有自由基产生。在酸性介质中用氧化还原滴定法研究了铈(Ⅳ)离子在痕量铱(Ⅲ)离子催化作用下,于298-313K区间氧化1,2-丙二醇(PRD)的反应动力学。结果表明：反应对铈(Ⅳ)离子为一级,对铱(Ⅲ)离子是正分数级,对PRD的反应级数为正分数级。准一级速率常数κobs随[H+]增加而增加,随[HSO4-]增加而减小,反应中有自由基产生。在酸性介质中用氧化还原滴定法研究了铈(Ⅳ)离子在痕量铱(Ⅲ)离子催化作用下,于298-313K区间氧化乙二醇(EG)的反应动力学。结果表明反应对铈(Ⅳ)离子和铱(Ⅲ)离子均为一级,对EG为正分数级。准一级反应速率常数κobs随[HSO4-]增加而减小,随[H+]的增大而增大。反应中有自由基产生。在酸性介质中用氧化还原滴定法研究了铈(Ⅳ)离子在铬(Ⅲ)离子催化作用下,于303K-318K区间氧化甲酸的反应动力学。结果表明反应对铈(Ⅳ)和甲酸均为一级,准一级速率常数κobs随催化剂[Cr(Ⅲ)]增加而增大,亦随[H+]增加而增大,而随[HSO4-]增加而减小。反应中有自由基产生。通过κobs与[HSO4-]的依赖关系,并结合Ce(Ⅳ)在溶液中的平衡,找出上述各个反应体系的动力学活性物种多数为Ce(SO4)2。通过假设提出的反应机理能很好的解释实验现象,并求得不同温度下的速控步骤的速率常数及298K时的活化参数。此外,本文还借助紫外可见光谱对反应机理进行了佐证。上述系统研究为催化剂在工业生产中的应用以及分析化学中的定量分析提供了一定的理论依据。更多还原

【Abstract】 The studies of kinetics and mechanism of transition metal ions catalyzed oxidation of some organic compounds by Ce(IV) in aqueous sulfuric acid media, monitoring by spectro-photometrically and titrimetric techniques. Oxidation products have been identified and characterized by chemical methods and IR spectroscopy respectively. Through analysis of the oxidation products and kinetic data, the corresponding mechanism has been deduced.The kinetics and mechanism of ruthenium(Ⅲ) catalyzed oxidation of tetrahydrofurfuryl alcohol(THFA) by cerium(Ⅳ) in sulfuric acid media has been investigated spectrophoto-metrically in the temperature range of 298-313K. It is found that the reaction is of first-order with respect to Ce(Ⅳ), and a positive fractional order with respect to THFA and Ru(Ⅲ). The pseudo first-order rate constantκobs decreases with the increase of [HSO4-]. Under the protection of nitrogen, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals.The kinetics and mechanism of ruthenium(Ⅲ) catalyzed oxidation of 1,2-propanediol (PRD) by cerium(Ⅳ) in sulfuric acid media has been investigated by titrimetric technique of redox in the temperature range of 288-303K. It is found that the reaction is of zero-order with respect to Ce(Ⅳ), first-order to Ru(Ⅲ) and negative fractional order with respect to PRD. It is found that the pseudo first-order rate constantκobs increases with the increase of [H+]. Under the protection of nitrogen, the reaction system can’t initiate polymerization of acrylonitrile, indicating no generation of free radicals.The kinetics of ruthenium(Ⅲ) catalyzed oxidation of isopropanol(IPA) by cerium(Ⅳ) in sulfuric acid media has been investigated by titrimetric technique of redox in the temperature range of 298-313K. It is found that the reaction is of first-order with respect to Ce(Ⅳ) and Ru(Ⅲ), and zero-order with respect to IPA. It is found that the pseudo first-order rate constantκobs increases with the increase of [H+], but decreases with the increase of [HSO4-]. Under the protection of nitrogen, the reaction system can’t initiate polymerization of acrylonitrile, indicating no generation of free radicals.The kinetics and mechanism of iridium(Ⅲ) catalyzed oxidation of ethanol amine(EAN) by cerium(Ⅳ) in sulfuric acid media has been investigated by titrimetric technique of redox in the temperature range of 298-313K. It is found that the reaction is of first-order with respect to Ce(Ⅳ) and Ir(Ⅲ), and a positive fractional order with respect to EAN. It is found that the pseudo first-order rate constantκobs decreases with the increase of [H+] and [HSO4-]. Under the protection of nitrogen, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals.The kinetics and mechanism of trace iridium(Ⅲ) catalyzed oxidation of 1,2-propanediol (PRD) by cerium(Ⅳ) in aqueous sulfuric acid media has been investigated by titrimetric technique of redox in the temperature range of 298-313K. The results show that the reaction is of first-order with respect to Ce(Ⅳ), and positive fractional order with respect to Ir(Ⅲ) and PRD. It is found that the pseudo first-order rate constantκobs increases with the increase of [H+], but decreases with the increase of [HSO4-]. Under the protection of nitrogen, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals.The kinetics and mechanism of trace iridium(Ⅲ) catalyzed oxidation of ethylene glycol(EG) by cerium(Ⅳ) in aqueous sulfuric acid media has been investigated by titrimetric technique of redox in the temperature range of 298-313K. It is found that the reaction is of first- order with respect to Ce(Ⅳ) and Ir(Ⅲ), and a positive fractional order with respect to EG. It is found that the pseudo first-order rate constantκobs increases with the increase of [H+], but decreases with the increase of [HSO4-]. Under the protection of nitrogen, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals.The kinetics and mechanism of trace chromium(Ⅲ) catalyzed oxidation of formic acid by cerium(Ⅳ) in aqueous sulfuric acid media has been investigated by titrimetric technique of redox in the temperature range of 303K-318K. It is found that the reaction is of first-order with respect to Ce(Ⅳ) and formic acid. It is found that the pseudo first-order rate constantκobs increases with the increase of [Cr(Ⅲ)] and [H+], but decreases with the increase of [HSO4-]. Under the protection of nitrogen, the reaction system can initiate polymerization of acrylonitrile, indicating the generation of free radicals.From the hydrogensulphate dependence and the equilibriums of Ce(Ⅳ) in the aqueous solution, Ce(SO4)2 has been found as the kinetically active species in most cases which have been discussed above. The proposed mechanism could satisfactorily explain the experimental results. Meanwhile, the rate constants(κ) at different temperatures for the rate determining step together with activation parameters(298K) were evaluated.Moreover, UV-vis absorption spectrums were used to support the proposed mechanism.The aboved systematic study can provide some theoretical foundation for the application of the catalysts in industrial production and quantitative analysis of analytical chemistry.更多还原