化学学报 ›› 1988, Vol. 46 ›› Issue (3): 217-221. 上一篇    下一篇

研究论文

5-硝基尿嘧啶电化学还原机理的探讨

胡渝;胡志彬;汪正浩   

  1. 北京师范大学化学系
  • 发布日期:1988-03-15

An approach to the mechanism for the electrochemical reduction of 5-nitrouracil

HU YU;HU ZHIBIN;WANG ZHENGHAO   

  • Published:1988-03-15

本文采用循环伏安法、恒电位电解法结合紫外光谱以及电子自旋共振波谱(ESR)方法对5-硝基尿嘧啶(5NU, 1)在DMSO中Ag-Hg电极上的电化学还原过程进行了研究, 并测定了反应中间物自由基的性质及其动力学规律. 实验结果表明, 1在DMSO中可有二个还原过程. 第一过程为1四电子还原为5-羟胺基尿嘧啶, 反应中所需质子由1提供. 第二个过程为失去质子后形成的阴离子5NU^-(2)在较负的电位下单电子还原为二价阴离子自由基, 后者可用ESR进行现场检测和研究, 其ESR参数分别为: 偶合常数αN=14.6G, αH=5.2G, 自由基g因子, g=2.005. 自由基的衰变反应为夺取1的质子, 反应的速度常数k1=52mol^-^1.dm^3.s^-^1.

关键词: 硝基化合物, 氧化还原反应, 反应机理, 电子自旋共振谱法, 电解法, 膜电极, DMSO, 反应速度常数, 电化学反应, 尿嘧啶

The electrochem. reduction of 5-nitrouracil (I) was investigated on Ag-Hg cathode in DMSO by cyclic voltammetry, controlled potential electrolysis, combined with UV and ESR spectroscopy. The results indicated that I could be reduced to 5-hydroxyaminouracil and simultaneously participated in the reaction as a proton donor. The anion of I was reduced at a more neg. potential. Some ESR parameters of the free radical which was generated in the reduction and the kinetic constant for the reaction were determine experimental The mechanism of the reduction of I was proposed according to the results.

Key words: NITRO COMPOUNDS, OXIDATION REDUCTION REACTION, REACTION MECHANISM, ELECTRON SPIN RESONANCE SPECTROMETRY, ELECTROLYTIC METHOD, MEMBRANE ELECTRODES, DMSO, REACTION RATE CONSTANT, ELECTROCHEMICAL REACTION, URACIL

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