4-氨基吡啶电化学合成工艺研究

Process Research on the Electrosynthesis of 4-Aminopyridine

在阳离子隔膜电解槽用阴极恒电位的方法电化学合成了4-氨基吡啶,并对工艺条件进行了优化。循环伏安法表明,4-硝基氮氧化吡啶的还原过程有多个不稳定的中间产物生成。以铅粒为阴极,钛网镀二氧化铅为阳极,阴极液pH=3,4-硝基氮氧化吡啶质量百分浓度为1%,硫酸铵为支持电解质,10%的硫酸溶液为阳极液,还原电量为200%的理论电量及50℃下4-氨基吡啶的收率达88.2%,电流效率44.1%。该工艺过程简单,收率高,是可望取代污染严重的铁粉还原的绿色合成路线。

In a cationic membrane electrolytic cell, 4-aminopyridine was synthesized by constant potential of cathode technique and the process conditions were optimized. Its cyclic voltammetry shows that there exist quite a number of unstable intermediates during the electroreduction of 4-nitropyridine 1-oxide. Under the optimal conditions, which are as follows: granular lead used as cathode, Ti-base lead dioxide as anode and calomel electrode as reference electrode, the water solution of 4-nitropyridine-1-oxide with pH=3 and 1% mass concentration as cathodic electrolyte and the solution of sulfuric acid with 10% mass concentration as anodic electrolyte, ammonium sulfate as supporting electrolyte, supplying 200% theoretic electric quantity and the temperature at 50°C, the 88.2% electrolyses yield of 4-aminopyridine and 44.1% current efficiency can be reached respectively. This green synthesis technology, characterized by simple process and high yield, is expected to instead ferrous reduction, which pollutes environment seriously.