碱性介质中二过碘酸合铜(Ⅲ)氧化三乙醇胺的动力学及机理

Kinetics and Mechanism of Oxidation of Triethanolamine by Diperiodatocuprate(Ⅲ) with Spectrophotometry in Alkaline Medium

在碱性介质中,用分光光度法研究了二过碘酸合铜(Ⅲ)配离子氧化三乙醇胺的反应动力学及机理.结果表明:反应对DPC为一级,对TEA为分数级;在保持准一级条件下,表观速率常数随着c(OH-)增大而增大,随着c(IO4-)增加而减小,且有负盐效应.提出了包括配离子和三乙醇胺形成络合物的前期快速平衡的反应机理,由假设的反应机理推出的速率方程能很好地解释全部实验现象,并进一步求得速控步骤的速率常数和活化参数.

The kinetics of oxidation of triethanolamine （TEA） by diperiodatocuprate（ Ⅲ ） complex （DPC） in alkaline medium is studied by spectrophotometry. The reaction rate shows first order dependence in DPC and fractional order in TEA. It is found that under the conditions of the pseudo-first order, the observed rate constants kobs decrease with the increase of c （IO4^ - ） but increase with the increase of c （OH^-）. There is a negative salt effect. A plausible mechanism involving a pre-equilibrium of a adduct formation between the complex and TEA is proposed. The rate equations derived from the mechanisms can explain all experimental results. The activation parameters along with the rate constants of the rate-determining step are calculated.