无溶剂微波辐射下Brnsted酸性离子液体催化合成系列乳酸酯  

Solvent-Free Synthesis of a Series of Lactates with Novel Brnsted Acidic Ionic Liquids as Catalysts Under Microwave Irradiation

作　　者：李心忠[1] 林棋[1] 

机构地区：[1]闽江学院化学与化学工程系,福建福州350108

出　　处：《石油化工》2010年第3期262-268,共7页Petrochemical Technology

基　　金：福建省自然科学基金资助项目(2008J0164);福建省教育厅科研项目(JA09189);闽江学院科研启动项目(YKQ0805)

摘　　要：以N-甲基咪唑、吡啶和苄基氯等为原料合成了4种Brnsted酸性离子液体——1-苄基-3-甲基咪唑硫酸氢盐、1-苄基-3-甲基咪唑磷酸二氢盐、N-苄基吡啶硫酸氢盐和N-苄基吡啶磷酸二氢盐,它们溶于水、乙醇,不溶于乙醚、乙酸乙酯等非极性有机溶剂,黏度分别为2.630,6.430,2.750,6.370Pa.s(28℃),含水量(质量分数)分别为3.1%,3.4%,3.5%,3.8%。以这4种离子液体作为催化剂和反应介质,考察了乳酸与直链脂肪醇、环己醇、苯甲醇在无溶剂、微波辐射条件下的Fischer酯化反应。实验结果表明,当n(乳酸)∶n(醇)∶n(离子液体)=1∶1∶0.5、反应时间20～35min、80～120℃时,酯化率为81.4%～97.1%、乳酸酯的收率为74.3%～88.8%。离子液体经再生脱水后可循环使用,循环使用3次后,催化活性基本保持不变。Four Br6nsted acidic ionic liquids （BAILs）, namely 1-benzyl-3- methylimidazolium hydrogen sulfate, 1-benzyl-3-methylimidazolium hydrogen phosphate, N-benzyl pyridinium hydrogen sulfate and N-benzyl pyridinium hydrogen phosphate, were synthesized from N-methylimidazole, pyridine, benzyl chloride etc.. These BAILs are soluble in both water and alcohol but insoluble in non-polar organic solvents such as ethyl ether and ethyl acetate. Their viscosities are 2. 630, 6. 430, 2. 750 and 6. 370 Pa · s （ 28℃ ）, respectively. And their water mass fractions are 3. 1%, 3.4%, 3.5 % and 3.8 %, respectively. With the BAILs as reaction media and catalysts, Fischer esterifications of lactic acid with straight chain aliphatic alcohols, cyclohexanol and benzyl alcohol with solvent-free under microwave irradiation were studied. Under the conditions of n （lactic acid） ： n （alcohol） ： n（BAILs） 1 ： 1 ： 0. 5, reaction time 20 - 35 rain, 80 - 120℃ and microwave irradiation, esterification rates and lactate yields in the Fischer esterifications were 81.4% -97.1% and 74.3% - 88.8%, respectively. The BAILs could be recovered easily and recycled three times without any significant loss in catalytic activity.

关 键 词：Brnsted酸性离子液体催化剂 微波辐射 无溶剂合成 乳酸酯 乳酸 醇 

分 类 号：TQ426.99[化学工程]