2甲-基吡啶在丙酮-水混合溶剂中的电氧化

在质子交换膜为隔膜的电解槽内,以2甲-基吡啶为原料,在丙酮/水混合溶剂中,以PbO2为阳极,电氧化合成了2-吡啶甲酸。通过循环伏安、线性扫描伏安和恒电位电解实验,考察了丙酮与水体积比、反应温度、硫酸浓度、反应物2-甲基吡啶浓度和阳极电位对选择性和电流效率的影响。结果表明,V(丙酮)∶V(水)=3∶1,硫酸浓度1.0~1.2 mol/L,2甲-基吡啶浓度0.5 mol/L,温度30℃,阳极电位1.75~1.80 V,生成2吡-啶甲酸的选择性可达88.7%,电流效率达到48.3%。而在纯水作溶剂的溶液中,相同条件下生成2-吡啶甲酸的选择性和电流效率仅分别为67.4%和42.2%。

Electrooxidation of 2-Methylpyridine in Acetone/Water Mixed Solvents

In an electrolytic cell with proton exchange membrane as diaphragm,2-pyridinecarboxylic acid was prepared in acetone/water mixed solvents by direct electrooxidation of 2-methylpyridine at a PbO_2 electrode.The effect of volume ratio of acetone to water,temperature,anode potential,concentration of sulfuric acid and 2-methylpyridine on the selectivity and the current efficiency were studied by using cyclic voltammetry,linear scan voltammetry and potentiostatic electrolysis.The optimal reaction conditions were found as volume ratio of acetone to water 3∶1,reaction temperature 30 ℃,anode potential 1.75～1.80 V,concentration of sulfuric acid 1.0～1.2 mol/L and concentration of 2-methylpyridine 0.5 mol/L.The selectivity and current efficiency for electrosynthesis of 2-pyridinecarboxylic acid in acetone/water mixed solvents reached 88.7% and 48.3%,respectively;whereas with pure water as solvent under same conditions,the selectivity and current efficiency were 67.4% and 42.2%,respectively.