酸性离子液体的制备、表征及在苯氨基甲酸甲酯与甲醛缩合反应中的应用
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摘要
针对液体酸存在的腐蚀设备、污染环境等缺点及固体酸需有机溶剂参与且催化效果较差等问题,本文制备了一系列酸性离子液体(ILs),表征了其结构并考察了它们在苯氨基甲酸甲酯(MPC)与甲醛缩合生成4,4’-二苯甲烷二氨基甲酸甲酯(4,4’-MDC)反应中的溶剂和催化性能。
制备了一系列以烷基咪唑和烷基吡啶为阳离子的离子液体,并将其作为溶剂兼催化剂用于MPC与甲醛的缩合反应中。结果表明,HBF4酸化1-乙基-3-甲基咪唑四氟硼酸盐([emim]BF4)离子液体具有较高的催化活性。以HBF4过量20%的酸化离子液体[emim]BF4为溶剂兼催化剂,考察了反应温度、原料配比、离子液体用量及反应时间等因素对4,4’-MDC合成反应的影响。筛选出适宜的反应条件为:70℃,MPC与HCHO摩尔比为4/1,离子液体与MPC质量比为4/1,1.5 h,此时4,4’-MDC产率为71.7%,选择性为71.9%。借助超声波对反应后的酸化离子液体进行萃取提纯,处理后的酸化离子液体循环使用四次其催化活性基本保持不变。为了更好地了解酸化离子液体[emim]BF4催化活性与其结构的关系,借助1H NMR分析等表征手段判定酸化离子液体阳离子是咪唑环与水分子(或H2O与HBF4二者混合物)以氢键为主要结合力所构成的大分子基团。
合成了一系列以1-(丁基-4-磺酸基)-3-甲基咪唑([HSO3-bmim])为阳离子的功能化离子液体,通过吡啶探针红外光谱分析法测定了其酸类型均为Br?nsted酸。采用Hammett指示剂与紫外联用法对离子液体的酸强度进行测定,结果发现各离子液体的酸强度能与其催化效果较好关联。其中[HSO3-bmim]CF3SO3酸强度最强,催化效果也最好,在反应条件为70℃,40 min,MPC与HCHO摩尔比为10/1,离子液体与MPC质量比为4.5/1时,MDC产率为89.9%,选择性为74.9%。在反应液中加水可使产品析出,离子液体经减压蒸馏除水后可直接循环使用,且循环使用四次活性无明显下降。
The synthesis of methylene diphenyl dimethylcarbamate (4,4’-MDC) from methyl N-phenyl carbamate (MPC) and formaldehyde (HCHO) has been investigated in the presence of several environmentally friendly acidic ionic liquids (ILs) as both the catalyst and the reaction solvent, for the liquid acid catalysts cause corrosion to the equipment and result in environmental pollution while solid acid catalysts not only deactivate rapidly but also need organic solvents for the condensation reaction.
Several kinds of ILs with alkyl groups in imidazolium or pyridinium cations were synthesized,and their catalytic and solvent performances were evaluated in the condensation reaction of MPC with HCHO. The result showed that [emim]BF4 ILs modified with H+ had better catalytic activity. The influences of reaction temperature, molar ratio of MPC to HCHO, the amount of ILs and reaction time on 4,4’-MDC synthesis reaction were studied using the [emim]BF4 ILs with the excess of HBF4 of 20% as both the catalyst and the reaction solvent. Under the suitable reaction conditions of 70℃, molar ratio of MPC to HCHO=4/1, mass ratio of ILs to MPC=4/1 and reaction time 1.5 h, the yield and the selectivity of 4,4’-MDC were 71.74% and 71.91%, respectively. The ILs was reused four times after treated by ultrasonic extraction with CHCl3 and no significant activity loss was observed after the second run. In order to understand the relationship between the catalytic activity of [emim]BF4 modified with H+ and its chemical structure, 1 H NMR and traditional experiment method were utilized and the structure of imidazolium cation was proved to be a macromolecular group formed by hydrogen-bonded with H2O(or the mixture of H2O and HBF4 ).
Five sulfonic acid-functionalized ionic liquids (SFILs) with 1-(butyl-4-sulfonate) -3- methyl imidazolium ([HSO3-bmim]) as the cation were prepared. The Br?nsted acidity of the SFILs was confirmed by FT-IR using pyridine as a probe molecule and the acid strength of the SFILs was determined by the Hammett method combined with UV-visible spectroscopy. The result showed that the acid strength of SFILs was consistent with their catalytic activity for the synthesis of 4,4’-MDC. Among the SFILs, [HSO3-bmim]CF3SO3 with the highest acid strength showed the best catalytic activity. The influences of reaction conditions on 4,4’-MDC synthesis in the presence of [HSO3-bmim]CF3SO3 were studied. Under the suitable reaction conditions of 70℃, 40 min, molar ratio of (MPC)/(HCHO)=10/1 and mass ratio of (ILs)/(MPC)=4.5/1, the yield and selectivity of 4,4’-MDC were 89.9 % and 74.9 %, respectively. SFILs could be reused four times after the removal of water and no significant loss in the catalytic activity was observed.
制备了一系列以烷基咪唑和烷基吡啶为阳离子的离子液体,并将其作为溶剂兼催化剂用于MPC与甲醛的缩合反应中。结果表明,HBF4酸化1-乙基-3-甲基咪唑四氟硼酸盐([emim]BF4)离子液体具有较高的催化活性。以HBF4过量20%的酸化离子液体[emim]BF4为溶剂兼催化剂,考察了反应温度、原料配比、离子液体用量及反应时间等因素对4,4’-MDC合成反应的影响。筛选出适宜的反应条件为:70℃,MPC与HCHO摩尔比为4/1,离子液体与MPC质量比为4/1,1.5 h,此时4,4’-MDC产率为71.7%,选择性为71.9%。借助超声波对反应后的酸化离子液体进行萃取提纯,处理后的酸化离子液体循环使用四次其催化活性基本保持不变。为了更好地了解酸化离子液体[emim]BF4催化活性与其结构的关系,借助1H NMR分析等表征手段判定酸化离子液体阳离子是咪唑环与水分子(或H2O与HBF4二者混合物)以氢键为主要结合力所构成的大分子基团。
合成了一系列以1-(丁基-4-磺酸基)-3-甲基咪唑([HSO3-bmim])为阳离子的功能化离子液体,通过吡啶探针红外光谱分析法测定了其酸类型均为Br?nsted酸。采用Hammett指示剂与紫外联用法对离子液体的酸强度进行测定,结果发现各离子液体的酸强度能与其催化效果较好关联。其中[HSO3-bmim]CF3SO3酸强度最强,催化效果也最好,在反应条件为70℃,40 min,MPC与HCHO摩尔比为10/1,离子液体与MPC质量比为4.5/1时,MDC产率为89.9%,选择性为74.9%。在反应液中加水可使产品析出,离子液体经减压蒸馏除水后可直接循环使用,且循环使用四次活性无明显下降。
The synthesis of methylene diphenyl dimethylcarbamate (4,4’-MDC) from methyl N-phenyl carbamate (MPC) and formaldehyde (HCHO) has been investigated in the presence of several environmentally friendly acidic ionic liquids (ILs) as both the catalyst and the reaction solvent, for the liquid acid catalysts cause corrosion to the equipment and result in environmental pollution while solid acid catalysts not only deactivate rapidly but also need organic solvents for the condensation reaction.
Several kinds of ILs with alkyl groups in imidazolium or pyridinium cations were synthesized,and their catalytic and solvent performances were evaluated in the condensation reaction of MPC with HCHO. The result showed that [emim]BF4 ILs modified with H+ had better catalytic activity. The influences of reaction temperature, molar ratio of MPC to HCHO, the amount of ILs and reaction time on 4,4’-MDC synthesis reaction were studied using the [emim]BF4 ILs with the excess of HBF4 of 20% as both the catalyst and the reaction solvent. Under the suitable reaction conditions of 70℃, molar ratio of MPC to HCHO=4/1, mass ratio of ILs to MPC=4/1 and reaction time 1.5 h, the yield and the selectivity of 4,4’-MDC were 71.74% and 71.91%, respectively. The ILs was reused four times after treated by ultrasonic extraction with CHCl3 and no significant activity loss was observed after the second run. In order to understand the relationship between the catalytic activity of [emim]BF4 modified with H+ and its chemical structure, 1 H NMR and traditional experiment method were utilized and the structure of imidazolium cation was proved to be a macromolecular group formed by hydrogen-bonded with H2O(or the mixture of H2O and HBF4 ).
Five sulfonic acid-functionalized ionic liquids (SFILs) with 1-(butyl-4-sulfonate) -3- methyl imidazolium ([HSO3-bmim]) as the cation were prepared. The Br?nsted acidity of the SFILs was confirmed by FT-IR using pyridine as a probe molecule and the acid strength of the SFILs was determined by the Hammett method combined with UV-visible spectroscopy. The result showed that the acid strength of SFILs was consistent with their catalytic activity for the synthesis of 4,4’-MDC. Among the SFILs, [HSO3-bmim]CF3SO3 with the highest acid strength showed the best catalytic activity. The influences of reaction conditions on 4,4’-MDC synthesis in the presence of [HSO3-bmim]CF3SO3 were studied. Under the suitable reaction conditions of 70℃, 40 min, molar ratio of (MPC)/(HCHO)=10/1 and mass ratio of (ILs)/(MPC)=4.5/1, the yield and selectivity of 4,4’-MDC were 89.9 % and 74.9 %, respectively. SFILs could be reused four times after the removal of water and no significant loss in the catalytic activity was observed.
引文
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2 刘元兰,严永华. 离子液体-- 一种新型的绿色化学反应介质. 化学教育,2004,(8):7-8
3 Wilkes J S A.Short History of Ionic Liquids-from Molten Salts to Neoteric Solvents.Green Chemistry, 2002, 4(2): 73-80
4 王均凤,张锁江,陈惠萍,等. 离子液体的性质及其在催化反应中的应用. 过程工程学报,2003,3(2):177-185
5 Sumei Zhang,Yawei Hou,etal.Preparation and charaterization of novel ionic liquid based on benzotriazolium cation.Electrochimica Acta, 2005, 50: 4097-4130
6 石顺存,,易平贵,曹晨忠,等. 新型离子液体的合成及其阳离子基团缓蚀性能. 化工学报,2005,56(6):1112-1119
7 Yurii L.Yagupolskii,Taras M.Sokolenko,etal.Novel ionic liquids—Imidazolium salts with a difluoromethylene fragment directly bonded to the nitrogen atom.Journal of Fluorine Chemistry, 2005.126: 669–672
8 高歌,徐海涛,赵大成,等. 烯丙基咪唑离子液体的合成与溶液性能. 化工新型材料,2005,33(5):27-29
9 石家华,孙逊,杨春和,等. 离子液体研究进展. 化学通报,2002,4:243-250
10 韩金玉,黄鑫,王华,等. 绿色溶剂离子液体的性质和应用研究进展. 化学工业与工程,2005,22(1):62-66
11 赵东滨,寇元.室温离子液体:合成、性质及应用.大学化学,2002,17(1):42-46
12 郭文希,高鹏,张姝妍,等. 室温离子液体的理化性能. 辽宁化工,2003,32(6):256-259
13 沈玉龙,魏利滨,曹文华. 绿色化学. 北京: 中国环境出版社,2004
14 P A Z Suarez,J E L Dullies,S Einloft,R F De Souza,J Doupont.Polyhedron,2003,(15):1217
15 阎立峰,朱清时. 离子液体及其在有机合成中应用. 化学通报,2001,11:673-679
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