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化学学报
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化学学报 ›› 1989, Vol. 47 ›› Issue (4): 313-318.    下一篇

研究论文

Cu(II)氧化抗坏血酸的动力学和机理

许金   

  1. 北京医科大学药物理化学教研室
  • 发布日期:1989-04-15

Kinetics and mechanism of the oxidation reaction of ascorbic acid by Cu(II)

XU JIN   

  • Published:1989-04-15

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本文在总离子强度I=1.00mol.dm^-^3、[Cu^2^+]>>[H2A]、[H^+]>>[H2A]、无氧及无缓冲剂存在的条件下, 研究Cu(II)氧化抗坏血酸(H2A)的动力学和机理. 发现Cu(II)与H2A不发生配位反应, 但以Cl^-存在的情况下, 确有Cu(II)的H2A配合物生成, Cu(II)氧化H2A反应的速率方程为r={a+b[Cl^-]}[Cu^2^+]{[H+]+Ka}^-^2, 25℃时a和b值分别为4.08×10^-^4s^-^1和0.555dm^3.s^-^1.mol^-^1. Cu(II)氧化H2A反应的表观活化能为68.1KJ.mol^-^1. 根据动力学结果, 提出了反应机理, 并给出了配合物ClCuHA的结构形式.

关键词: 氧化, 反应机理, 反应动力学, 铜, 维生素C

The title reaction of ascorbic acid (H2A) was studied at [Cu2+] >> [H2A] and [H+] >> [H2A]. The effect of chloride anion on the kinetics and mechanism has been examined at [H+] = 1.00 ?10-3 mol dm-3 and the chloride concentration up to 7.00 ?10-3 mol dm-3. The Arrhenius activation energy is 68.1 kJ mol-1. The stop-flow spectrum shows that no CuHA+ complex is formed in the system of Cu(II)-ascorbic acid, but the complex ClCuHA is formed in the presence of Cl-.

Key words: OXIDATION, REACTION MECHANISM, REACTION KINETICS, COPPER, VITAMIN C

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