碱性介质中分光光度法研究二过碘酸合铜(Ⅲ)氧化1,2-丙二胺反应动力学及机理

摘要

The kinetics of oxidation of 1,2-propanediamine (PDA) by diperiodatocuprate(Ⅲ) complex (DPC)was studied spectrophotometrically in alkaline medium.The reaction rate showed first order dependence in DPC and 1 ＜nap＜ 2 in PDA.It was found that under the conditions of the pseudo-first order ([PDA]0＞＞[Cu(Ⅲ)]0),the rate constant kobs increased with increase in [OH-],and then it decreased with increase in [IO4-].There is a negative salt effect.A plausible mechanism involving a pre-equilibrium of an adduct formation between the complex and PDA was proposed.The rate equations derived from mechanisms can explain all experimental results.The activation parameters along with the rate constants of the rate-determining step were calculated.%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(DPC)氧化1,2-丙二胺(PDA)的反应动力学及机理.结果表明,反应对DPC为一级,对PDA为1＜ nap＜2(nap代表表观反应级数)；在保持准一级条件([PDA]0＞＞[Cu(Ⅲ)]0)下,表观速率常数kobs随[OH-]增大而增大,随着[IO4-]增加而减小,且有负盐效应.提出了包括配离子和1,2一丙二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的解释全部实验现象,并进一步求得速控步的速率常数和活化参数.