Lewis酸性离子液体bmimPF6催化合成乙酸异戊酯

采用吡啶红外光谱探针法测定了离子液体1-丁基-3-甲基咪唑六氟磷酸盐(bm imPF6)的酸性,并将该Lew is酸作为催化剂用于乙酸与异戊醇合成乙酸异戊酯的反应,探讨了酸醇物质的量比、离子液体用量、反应时间及离子液体循环使用次数对酯收率的影响。结果表明,酸醇物质的量比为1.2∶1,bm imPF6用量为反应物质量的12.5%,反应温度为110℃,反应时间为2.0 h时,酯收率可达72.2%。反应产物与离子液体采用倾倒法即可分离,bm imPF6经真空干燥后循环使用4次,催化活性没有显著降低。

Synthesis of isoamyl acetate using Lewis acid ionic liquid bmimPF6 as catalyst

The acidity of Lewis acid ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate(bmimPF6) was determined by using pyridine as IR spectroscopic probe,and isoamyl acetate was synthesized with bmimPF6 as catalyst.The influencing factors on yield of isoamyl acetate such as molar ratio of isoamyl alcohol to acetic acid,dosage of the catalyst,reaction time,and times of recycling use of the catalyst on the yield of isoamyl acetate were examined.Optimal conditions was obtained as:n(acetic acid)∶n(isoamyl alcohol)=1.2∶1,with the dosage of bmimPF6 12.5%(w) of total reactants,at 110 ℃ and reaction for 2.0 h.Yield of isoamyl acetate achieves 72.2%.The catalyst can be conveniently separated from the reaction mixture by decantation and can be reused for 4 times without significant decline of the activity.