氧气部分替代硝酸氧化脱羧合成洋茉莉醛

Synthesis of Piperonal by Oxidative Decarboxylation with Oxygen Partially Substituted Nitric Acid

在氧气气氛中,硝酸氧化脱羧3,4-亚甲二氧基苯乙醇酸(DMA)后生成的NO很快氧化为NO2,与水作用后生成HNO3和HNO2可以继续参与反应,从而实现了氧气部分替代硝酸氧化脱羧合成洋茉莉醛的过程。在此过程中,NO2起到了O2传送带的作用,而HNO2则是反应真正的氧化剂。在低温、低浓度硝酸和亚硝酸钠引发剂存在条件下,考察了反应温度、硝酸浓度、硫酸浓度和反应时间等参数的影响。当n(HNO3)/n(DMA)=0.45且反应温度为331.2 K时,反应65 m in后氧气替代硝酸率达到32.9%,DMA转化率为97.0%,反应选择性为97.0%。根据实验结果,提出了进一步提高氧气替代硝酸率,从而实现O2作为氧化剂、HNO3作为催化剂的绿色过程的设想。

The synthesis of piperonal by nitric acid partially substituted with oxygen was achieved,because oxygen could quickly oxidize nitric oxide,which was the product of nitric acid oxidative decarboxylation of 3,4-methylenedioxymandelic acid（DMA） to piperonal,to NO2 that reacted with H2O and formed HNO3 and HNO2 again.For this reaction process,NO2 acted as the conveyor of oxygen and HNO2 was the real oxidant.The influences of reaction temperature,nitric acid concentration,sulfuric acid concentration and reaction time on the reaction were investigated under low temperature and low-concentration of nitric acid with sodium nitrite as an initiator.The respective oxygen substitution rate for nitric acid,DMA conversion and DMB selectivity reached 32.9%,97.0% and 97.0% after 65 min with nitric acid to DMA ratio of 0.45 and 331.2 K.Based on the results,a conception was proposed that a chemical process favorable to environment,in which oxygen would be used as the oxidant and the nitric acid as the catalyst,might be realized by further increasing the oxygen substitution rate.