2,3-吡啶二羧酸的合成

Synthesis of 2,3-Pyridine-Dicarboxylic Acid

以喹啉为原料,经氧化、碱解和酸化3步反应合成了2,3-吡啶二羧酸。考察了以氧化反应的滤液(即母液)为引发剂对氧化反应诱导期和2,3-吡啶二羧酸收率的影响,并对氧化反应的原料五水硫酸铜和酸化反应滤液中的2,3-吡啶二羧酸进行了回收。实验结果表明,加入母液,氧化反应的诱导期从7.10h缩短至2.63h,其原因可能为母液中含有的二氧化氯遇水产生自由基。适宜的氧化反应条件为:母液用量50g、反应时间12h、n(喹啉)∶n(氯酸钠)∶n(硫酸铜)∶n(浓硫酸)=1∶3.5∶1∶1.5、反应温度103℃。在此条件下,2,3-吡啶二羧酸的收率为67.3%(未含有回收的2,3-吡啶二羧酸),精制后产品纯度达99.89%。回收酸化反应滤液中的2,3-吡啶二羧酸后,2,3-吡啶二羧酸的收率提高5%。五水硫酸铜回收率达到94%。

2, 3-Pyridine-dicarboxylic acid with high purity was synthesized from a cheap material quinoline via a three-step method of oxidation, alkalization and acidification. Effects of recirculation of mother liquor, which was the filtrate of oxidation, on induction period of oxidation and yield of 2,3- pyridine-dicarboxylic acid were investigated. The 2, 3-pyridine-dicarboxylic acid in filtrate from the acidification and cupric sulfate from the oxidation were recovered. The optimal reaction conditions for the oxidation were as follows： n（quinoline）： n（ sodium chlorate）： n（ cupric sulfate）： n（ concentrated sulfuric acid） 1 ： 3.5 ： 1 ： 1.5, recirculation of mother liquor 50 g and reaction time 12 h at 103℃. Adding certain amount of mother liquid led to remarkable shortening of induction period of oxidation from 7.10 h to 2.63 h. The possible reason was the presence of free radical in mother liquor. Yield of 2,3-pyridine- dicarboxylic acid was 67.3%. The purity is 99.89% after purification. After recovery of 2,3-pyridinedicarboxylic acid from the filtrate, its yield increased by 5%. Recovery rate of cupric sulfate was 94%.