Synthesis, Properties And Application Of Guanidinium & Guanidinium Lonic Liquids

In the research of realizing green chemistry, looking for the green solvents and the catalyst for the friendly environment is one of the main research areas. The Room Temperature Ionic Liquids (RTILs) show useful properties such as thermal stability, insipid, nonflammable, high ionic conductivity, negligible vapor pressure and large electrochemical window, circular. The RTILs emerged as an alternative recyclable environmentally benign reaction media for chemical process including bio and chemical catalysis. The physical and chemical properties of RTILs, often defined as "green solvents and designer solvents", can indeed varied over a wide range by selection of suitable cations and anions. The most common RTILs in use are salts with N-alkylpyridinum and N,N-dialkylimidazolium cations, such as [Bmim][PF6] (1-butyl -3-Methy limidazolium hexafluorophosphate) and [Bmim][BF4] (1-butyl-3-methy limidazolium tetrafluoroborate). At present, in order to substitute toxic,harmful organic solvents and develop highly efficient green chemistry process,to develop synthesis and application of RTIL, especially, as solvents and catalysts have received much attention. There are several advantages and reasons for synthesizing alkylguanidinium-based ionic liquids: a. The positive charge in the guanidinium salts is delocalized over one carbon and three nitrogen atoms, which gives them a high degree of thermal stability compared to tetraalkylammonium salts. b.The alkyl-guanidinium halides are widely used as phase transfer catalyst due to their exceptional stability at high temperature. c. Alkylguanidinium exhibit some particularities due to its extraordinary bulkiness. For example, the literature reports structural features, which support the existence of an electron-deficient state at the central carbon atom surrounde by the three nitrogen atoms. In this paper, we designed and synthesized a series of guanidinium halides and guanidinium ionic liquids(GRTILs),and studied their properties and applications. The main content is outlined as following: 1.Guanidinium halides were synthesized with two routes. At first, Tetraalkylguanidine preparation involved the direct addition of secondary amines to alkylcyanamides, the hexaalkylguanidinium halide (GX) were prepared from tetraalkylguanidine with an alkylating agent in the presence of an alkaline reagent. The second method is oxalyl chloride. vilsmeier salt was synthesized from tetraalkylureas with oxalyl chloride, then react with amines to produce pentaalkyl -guanidine or hexaalkylguanidine. 2. Guanidinium ionic liquids were synthesized by ionic exchange. We studied in full the physico-chemical properties of a number of GRILs, involving density, viscosity, polarity, melt point, thermal stability and electrochemical property. The results as following: The density of GRTILs decreases as the bulk of the cation decreased and increases as the bulk of the anion increased. The viscosity of GRTILs decreases as the bulk of the anion and cation decreased. When we study the polarity of the GRTILs with the aid of the fluorescene spectra, we found that the polarity of displaying in the range polarity of the alcohols, moreover, the influence of anions and cations on polarity of the GRTILs were not obvious. DSC indicated they are stable...