碱性介质中分光光度法研究二过碘酸合铜(Ⅲ)氧化1,3-丙二醇反应动力学及机理

Kinetics and Mechanism of Oxidation of 1,3-propylene Glycol 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(DPC)氧化1,3-丙二醇(PG)的反应动力学及机理.结果表明,反应对DPC和PG均为一级,在保持准一级条件([PG]0[Cu(Ⅲ)]0)下,表观速率常数kobs随着[IO4-]增加而减小,随着[OH-]增大而增大,没有明显盐效应.据此提出了包括配离子和PG形成络合物的前期快速平衡的反应机理,由假设反应机理推出的速率方程能解释全部实验现象,进一步求得速控步的速率常数k和平衡常数K及活化参数.

Kinetics and mechanism of oxidation of 1,3-propylene glycol（PG） by diperiodatocuprater（ Ⅲ） （DPC） in aqueous alkaline medium have been studied by spectrophotometry in a temperature range of 298.2-313.2 K. The reaction order for 1,3-propylene glycol and Cu （ Ⅲ） are both found to be one and reaction rates decrease with increase in [IO4^-] and increase in [OH^-]. There isn＇t the effect of added KNO3. The products of oxidation are identified as the corresponding aldehyde alcohols. A mechanism of reaction involving a pre-equilibrium between DPC and [ Cu（OH）4 ]^- is proposed, which can explain all experimental observations. Activation parameters of the rate-determining step have been calculated.