1,3-二甲基-5-亚硝基-6-氨基脲嘧啶镍电极电化学加氢机理

Electrochemical hydrogenation mechanism of 6-amino-5-nitroso-1,3-dimethyluracil at a nickel electrode

采用稳态极化法、循环伏安法和恒电位库仑法研究了1,3-二甲基-5-亚硝基-6-氨基脲嘧啶(ANDMU)在镍电极上的电化学加氢机理,实验体系为pH 3的硫酸硫酸钾水溶液。结果表明,在镍电极析氢电位之前,在-0.7^-0.8 V(相对于Hg2SO4参比电极)ANDMU即发生加氢反应。随着pH值降低,还原电流增大,加氢反应速度增大,还原电位正移。反应受扩散控制,增大搅拌速度和提高温度都可以提高反应速度。ANDMU在镍电极上的电化学加氢反应机理与在铂电极上的情况相似,都是溶液中氢离子在电极表面得电子生成原子态氢还原ANDMU的EC(电化学反应后耦联有化学反应)过程。

The electrochemical hydrogenation of 6-amino-5-nitroso 1,3-dimethyluracil （ANDMU） on a smooth Ni electrode was studied with steady-state polarization, cyclic voltammetry, and constant-potentlal coulometry. One irreversible peak was found for -- 0.7 -- 0. 8V （vs. Hg2SO4） with cyclic voltammetry at pH 3 in a H2SO4-K2SO4 solution. The experimental results show that the 4 electrons are involved in the electrochemical reaction with hydrogen ions reduced on the Ni electrode surface to atomic hydrogen. The reaction is controlled by diffusion and the reaction rate increased with increasing temperature and stirring speed and with decreasing pH. As with a platinum electrode, the hydrogenation of 6-amino-S-nitro-so-l,3-dl-methyluracil on the smooth Ni electrode may be an electrochemical reaction followed by a chemical reaction.