Synthesis And Application Of Lewis Acidic Guanidinium Ionic Liquids

Ionic liquids are a kind of substance which consist of cations and anions, as well as they are liquid at room temperature or close room temperature, so they are called room temperature ionic liquids (RTILs). Generally, room temperature ionic liquids (RTILs) are made of relative bulky structure of organic cations and relative small structure of inorganic anions, they show useful physical properties, chemical properties , and they include modifiable cations and anions. these ILs are called "functional ionic liquid 'because of they are designed for specific needs, which include functional physical properties (such as fluidity, conductibility and liquid scope etc) and functional chemical properties (such as polarity, acidity etc). Now ,the research for ionic liquid mainly centralize on the synthesis of new functional ILs.Lewis acidic ionic liquids are not only used as reaction media ,but also they are effective lewis acid catalyst.the synthesis of Lewis acidic ionic liquids undergo zigzag process, when ionic liquids with AlCl3 as anion appeared, they were widely applied, however, these ionic liquids are sensitive for water and oxidative impurity, which restricted their wide application. Along with the further research of Lewis acidic ionic liquid , a lot of new Lewis acidic ionic liquid appeared, and these ionic liquid are stable in the air, These Lewis acid ILs, which consisting of different type of cations and anions display the special physics, chemical property, so we can synthesize novel Lewis acidic ionic liquids, in order that they were applied effectively in specific organic synthesis reaction. The guanidinium is a count for a lot of compounds, due to the structure characteristic of themselves, they have following characteristics: In the molecule structure, the positive charge distributes on three nitrogen atoms and the center carbon, making the molecule have the good thermal stability; In the molecule structure, with regulating the substitutents of three nitrogen atoms ,it can control the property of cations.a. the hydrogen atom which bonding with the three nitrogen atoms can form hydrogen bond with F, O, N.b.Regulating the substituted the alkyl of nitrogen atoms to change the size of the cations, the catalytic function of the molecule change .c.Regulating the substituted alkyl of three nitrogen atoms to chang the interaction between the substituted alkyl groups on three nitrogen atoms , the planar structure of the cation change occur, which make the cation express a special property.In the molecule structure, with regulating the anion, the properties of the moleculer are changed.In this paper, we used tetraalkylureas and oxalyl chloride as the starting materials to synthesize a series of hexalkylguanidium halides, and which subsequently reacted with Lewis acids such as AlCl3, ZnCl2 and SnCl2, a series of new Lewis acidic guanidinium ILs were obtained. In addition, the physical and chemical properties of the guanidinium ILs were investigated.We applied the synthetic lewis acidic guanidinium ionic liquids in the reaction of the opening of cyclic epoxides , and investigated the effect of reaction conditions such as the reaction time, reaction temperatures and the loadage of catalysts on the coversion and selectivity of the reaction.In addition, recylability of the guanidinium IL was also investigated. The results shows that the Lewis acidic guanidinium ILs are effective, recyclable towards the reaction of epxoides with aromatic amines.