微波辐射法合成α-紫罗兰酮的研究

Synthesis of α-ionone from radiation by microwave

以柠檬醛和丙酮为原料,在微波辐射条件下,经缩合反应合成了假性紫罗兰酮,再经环化反应合成了α-紫罗兰酮。重点探讨了催化剂的种类和用量、反应物配比、微波辐射时间和功率等因素分别对缩合和环化反应的影响,确定了在微波辐射下合成α-紫罗兰酮的工艺条件:缩合反应以KF/Al2O3为催化剂(与柠檬醛的质量比为1∶1),n(柠檬醛)∶n(丙酮)=1∶10,90 W微波辐射12 min;环化反应以固体硫酸氢钠作催化剂,其用量为0.287 g,60 W微波辐射5 min。与无微波辐射条件的合成方法相比,此法大大缩短了反应时间,简化了制备工艺流程,而且假性紫罗兰酮产率由92.6%提高到98.3%,α-紫罗兰酮的产率由60.0%提高到70.1%。

Pseudoionone was synthesized with citral and acetone as raw materials by condensation reaction under microwave radiation. The pseudoionone was further cyclized to form α- ionone. The influence of variety and dosage of catalyst, raw material ratio, time and power of microwave radiation on reaction were studied. Under the optimum conditions, in condensation, the best catalyst is KF/Al2O3, the mass ratio of KF/Al2O3 to citral is 1 ： 1, the molar ratio of citral to acetone is 1：10, time and power of microwave radiation is 12min and 90 W, respectively; in eyclization, the best catalyst is NaHSO4 （the amount of it is 0.287 g）, time and power of microwave radiation is 5 min and 60 W, respectively. The result showed that due to the action of microwave radiation the reaction time is greatly shortened and the yield is increased. The yield of pseudoionone increases from 92.6% to 98.3% at the optimum conditions. The yield of ionone increases 10% as campared with that without microwave radiation at the same conditions.