Investigation On The Properties Of Imidazole Anionic ILS And The Application In The Michael Addition Reaction

Ionic liquids, which are considered as novel and functional solvents, have being widely applied to many fields, including organic reactions, material preparation, electrochemistry, gas absorbing, extraction separation, biomass utilization and so on.Basic ionic liquids are the new type of functional ionic liquids containing basic center endured by the anion/ cation or both anion and cation. Compared with traditional base, basic ionic liquids have many advantages, such as strong basicity, stability in water and air, ease of separating and recycling. Therefore, basic ionic liquids are regarded as great potential candidates to replace traditional base catalysts and have attracted much attention from industrial and academic researchers.However, there are still many problems in the development of basic ionic liquids. For instance, the structure of basic ionic liquids is controversial, and how the basic ionic liquids play the role in the reactions is not clear. Hence, the studies of the structure of basic ionic liquids, and the interactions between reactions and basic ionic liquids in the reaction system, have an important theoretical significance for understanding the role of basic ionic liquids.Functional ionic liquid based on imidazole anion were synthesized in this paper. The microscopic states of the synthesized basic ionic liquids and interactions with aprotic/ protic solvent molecules have been studied using Nuclear magnetic resonance spectroscopy(NMR) technology. In this work, we focused our attention on the interactions of the basic ionic liquids with molecular solvents and their applications in Michael addition reaction. As a part of the project supported by the National Natural Science Foundation of China(No.21003039), the main content of the present work is as follows:1. A series of functional ionic liquids with imidazole anion were synthesized, including 1-alkyl-3-methylimidazolium imidazolide([Cnmim]Im n=2,4,6,8,10,12), 1,2-dimethyl-3-butylimidazolium imidazolide([C4mmim]Im), 1-hydroxylethyl-3-methylimidazolium imidazolide([HOEmim]Im) and tetrabutylammonium imidazolide([N4444]Im). Among these, [Cnmim]Im(n=10,12) and [N4444]Im have been synthesized for the first time. The structure and property of the synthesized ionic liquids were characterized by NMR technology, Differential Scanning Calorimeter(DSC), Thermo gravimetric analysis(TG) and basicity determination method. The influences of cation structure, alkyl chain length and nature of anion on the melting point, thermostability and basicity of the researched ionic liquids have been discussed.2. The microstructure of pure basic ionic liquids and ionic liquids [C4mim]Im dissolved in different polar solvents have been studied by NMR at 298.15 K. In addition, the interactions of anion and cation, and ions with solvents have been studied.3. The application of [C4mim]Im in the Micheal addition reaction were studied under solvent-free condition. The different substituted alpha, beta unsaturated compounds and nitrogen-bearing heterocyclic compounds were chosen as reactants. The effects of this imidazole anion ionic liquid as catalyst on Michael addition reaction have been investigated. Furthermore, the interactions between ionic liquid and reactants were investigated by NMR technology. According to this, the possible mechanism of this typical organic reaction was proposed.