2种添加剂在电有机合成中的应用

通过电解实验分别考察了5个阴极电还原反应和1个阳极电氧化反应在加入添加剂前后电流效率和转化率的变化。所选择的6个反应可以分为2类,一类是原料以分子形式存在于电解液中的反应,另一类是原料以离子形式存在于电解液中的反应。实验间二硝基苯电还原制间苯二胺,3-甲基吡啶氧化制烟酸和邻硝基酚电还原制邻氨基酚(酸性条件下)属于前一类反应,加入添加剂后,它们的电流效率分别由原来的65.69%、28.00%和45.09%变为66.15%、28.45%和37.07%,说明添加剂对原料以分子形式存在的反应没有作用或有抑制作用。实验邻硝基酚电还原制邻氨基酚(碱性条件下),丁二酸的电解全盛和水杨酸电还原制水杨醛属于后一类反应,加入添加剂后,它们的电流效率分别从原来的49.37%、65.06%和24.55%提高到75.80%、78.60%和30.06%,说明添加剂能够提高原料以离子形态存在的反应的电流效率。

Effect of Additives on Efficiency of Electrochemical Reactions

Five electroreductive reactions and one electrooxidative reaction were chosen to investigate the current efficiency and the percent conversion in the presence and in absence of additives by electrolysis.The result shows that the six reactions can be divided into two groups.The first group are the reactions whose reactants are molecules in electrolyte,and the second group are the reactions whose reactants are ions in electrolyte.For the former,the current efficiencies of the reduction of m-dinitrobenzene,the oxidation of 3-methylpyridine and the reduction of o-nitrophenol in sulfuric acid changed from 65.69%,28.00% and 45.09% to 66%,28.45% and 37.07% respectively by adding additive,which indicates that the additives have little or negative effect on the reactions whose reactants are molecules in electrolyte.For the latter,the current efficiencies of the reduction of o-nitrophenol in sodium hydroxide,the synthesis of succinic acid and the reduction of salicylic acid increased to 75.80%,78.60% and 30.06% from 49.37%,65.05% and 24.55% respectively by adding additive,which means that the additive will increase the current efficiency of the reaction whose reactants are ions in electrolyte.