新型离子液体型固体酸的合成及其在酯化反应中的应用

利用环己亚胺、1,3-丙烷磺酸内酯和Keggin型杂多酸合成了两种新型离子液体型固体酸1-(3-磺丙基)环己亚胺十二磷钨酸盐(HMIPS]3PW12O40)和1-(3-磺丙基)环己亚胺十二磷钼酸盐(HMIPS]3PMo12O40),采用1H NMR,31P NMR,FTIR,TG等方法对反应中间体和产物进行了表征。表征结果显示,所合成的HMIPS]3PW12O40和HMIPS]3PMo12O40是含Br?nsted酸的离子液体型固体酸,在室温下均为固体,能溶于水,其熔点分别为175.4℃和182.3℃。在酯化反应中,HMIPS]3PW12O40和HMIPS]3PMo12O40是一类反应控制自分离催化剂。以HMIPS]3PW12O40为催化剂,在n(乙酸):n(环己醇)=5:1、反应温度90℃和反应时间2.0 h的条件下,环己醇的转化率和乙酸环己酯的选择性分别为96.31%和99.26%;在n(柠檬酸):n(正丁醇)=1:5、反应温度120℃和反应时间3.0 h的条件下,柠檬酸的转化率和柠檬酸三丁酯的选择性分别为97.89%和98.49%。

Synthesis of Novel Ionic Liquid-Based Solid Acids and Their Catalytic Performances in Esterifications

Two novel ionic liquid-based solid acids,1-(3-sulfopyl) hexamethyleneiminium phosphotungstic acid(3PW12O40) and 1-(3-sulfopyl) hexamethyleneiminium phosphomolybdic acid(3PMo12O40),were synthesized from hexamethyleneimine,1,3-propane sultone and Keggin heteropoly acids.The novel ionic liquid-based solid acids and the intermediate 1-(3-sulfopropyl) hexamethyleneiminium(HMIPS) were characterized by means of 1H NMR,31P NMR,FTIR and TG.The results showed that 3PW12O40 and 3PMo12O40 were ionic liquid-based solid acids with Brnsted acidity,their melting points were 175.4 ℃ and 182.3 ℃ respectively,and they could dissolve in water and were solid at room temperature.3PW12O40 and 3PMo12O40 were reaction-controlled self-separated catalysts in esterification.Some esterification reactions on 3PW12O40 catalyst were studied.The conversion of cyclohexanol and the selectivity to cyclohexyl acetate could reach 96.31% and 99.26% respectively under the appropriate reaction conditions of n(acetic acid):n(cyclohexanol) 5:1,reaction temperature 90 ℃ and reaction time 2.0 h.The conversion of citric acid and the selectivity to tributyl citrate could reach 97.89% and 98.49% respectively under the condition of n(citric acid):n(n-butanol) 1:5,reaction temperature 120 ℃ and reaction time 3.0 h.