吗啡啉类酸性离子液体的合成及其催化酯化反应

SYNTHESIS OF MORPHOLINE ACIDIC IONIC LIQUID AND APPLICATION FOR ESTERIFICATION REACTION

制备了N-甲基-N-丁基吗啡啉硫酸氢盐([Nbmm]HSO4)和N-甲基-N-丁基吗啡啉对甲苯磺酸盐([Nbmm]PTSA)两种新型酸性离子液体。通过FT-IR和元素分析确认其结构。所合成的离子液体均溶解于强极性溶剂,且酸性较强。以乙酸和乙醇合成乙酸乙酯的反应为模型反应考察了离子液体催化酯化反应的催化活性,吗啡啉离子液体具有很好的催化活性,其强弱顺序为[Nbmm]HSO4>[Nbmm]PTSA。这与离子液体的酸性及其与原料、产物的溶解性有关。同时也说明吗啡啉离子液体的酸性主要由其阴离子决定。在n(环己烷)∶n(乙醇)∶n(乙酸)=0.88∶2∶1、离子液体[Nbmm]HSO4加入量为原料总质量的1.8%、反应时间为3h条件下,采用溶剂回流法合成乙酸乙酯收率达99.57%。脱水后离子液体重复使用5次,催化活性仍无明显下降。将[Nbmm]HSO4应用于乙酸正丁酯和油酸甲酯的合成也具有较高的催化活性。

Two new acidic morpholine ionic liquid, [Nbmm] HSO4 and [Nbmm]PTSA, were synthesized. The structure of IL was characterized by FT-IR and elemental analysis. Two ionic liquids were soluble in strong polar solvent and have strong acidity. The catalytic activity of the acidic ionic liquids for the esterification reaction of acetic acid with ethanol was measured. The results show that the morpholine ionic liquids have good catalytic activity and [Nbmm]HSO4 ：〉[Nbmm]PTSA, which is associated with acidity and solubility inthe material and product. At the same time, the acidity of ionic liquid is determined by the anion. The yield of acetic ester can be up to 99.57% by solvent refluxing when n（cyclohexane） ： n（ethanol） ： n（acetic acid）=0.88 ： 2 ： 1, catalyst addition is equal to 1.8% of material total mass and react for 3 h. The IL could reuse more than 5 times without significant decrease in activity after drying under vacuum. The ionic liquid [Nbmm]HSO4 has good catalytic activity in the synthesis of butyl actate and methyl oleate.