草酸在乙腈介质中的电化学还原行为

草酸在四乙基氯化铵的乙腈溶液中有较好的电化学还原性能。通过研究草酸在乙腈中的电化学行为,获得了草酸电化学还原的最佳条件,并合成相应的产物乙醛酸。采用单扫伏安法对有机溶剂(乙腈、四氢呋喃)、季铵盐支持电解质(四乙基氯化铵、四甲基氯铵、四丁基溴化铵)、电极材料进行了优化,得出以下结论,乙腈溶剂中草酸的电还原,可用0.1mol/L四乙基氯化铵为支持电解质,铂为阴极,采用无薄膜电解槽,电解时间5h,草酸的转化率为98%。该法具有简单、方便、电解液不受污染等优点,对乙醛酸的生产具有重要指导意义。通过不同电解时间产物的红外光谱分析,测定所得主要产物为乙醛酸。但是电解时,支持电解质四乙基氯化铵也发生了部分分解,生成了氯乙烷和乙胺,这还需在以后的实验中进一步选择。

The Electrochemical Reductive Behaviors of Oxalic Acid in Acetonitrile Solvent

Oxalic acid can be electrochemically reduced in the solution of acetonitrile of tetraethylammonium chloride. The optimum conditions of oxalic acid electro-reduction were obtained by the electrochemical behaviors of oxalic acid in acetonitrile solvent.Glyoxylic acid was synthesized. Using single sweep voltammetry method, the appropriate organic solvent including acetonitrile and tetrahydrofuran,supporting electrolyte including tetraethylammonium chloride,tetramethylammonium chloride and tetraethy- lammonium bromide, as well as the electrode materials were optimally selected. The experimental results show that the better solvent is acetonitrile, the supporting electrolyte is 0.1 mol/L tetraethylammonium chloride and the working electrode is platinum. The electrochemical reduction can be achieved in a undivided cell. The best conversion of oxalic acid is 98% at 5 hours. This prepared method is simple, convenient and has no pollution to the electrolyte. Through IR spectra analysis for the electrolysis product at different time, the main product is proved to be glyoxylic acid. Meanwhile the supporting electrolyte, i.e. tetraethylammonium is decomposed to chloroethane and ethylamine, so the supporting electrolyte should be improved in future.