Salt synthesis ionic liquid properties

E. Zygadlo-Monikowska, Z. Florjariczyk, J. Ostrowska, P. Boltromiuk, J. Frydrych, W. Sadurski, N. Langwald, Electrochim. Acta 2011,57,66-73. Synthesis and characterization of new trifluoroalkoxyborates lithium salts of ionic liquid properties. 

These properties have resulted in a veritable explosion of research into the synthesis, properties and uses of ionic liquids over the past decade, Figure 13.23. Recently, traditional non-coordinating anions like PF6 and BF4 are being abandoned as IFs enter mainstream applications, because of their toxicity. Non-toxic replacements include anions such as bis(trifyl)imide (CF3S02)2N. Other, less toxic cations are also increasingly popular, e.g. choline salts. 

Ionic liquids (ILs) have been recognized since the early 1900s. They are molten salts with low melting points, usually below 100°C. They were introduced in organic synthesis as a new class of polar, non-molecular solvents in the late 1990s and have recently attracted interest in a variety of fields since solvents are at the heart of most chemical processes and ionic liquids show an exclusive and fascinating wide range of physico-chemical properties. 

Yang et al. used a similar protocol (an ether functionality supported on a primary alkyl halide carrier) to introduce an acetal on either side of the imidazole ring generating an ether functionalised ionic liquid (IL) imidazolium salt [183] (see Rguie 3.58). The anion could be varied without loss of the IL property (melting point below 1(X) °C) [184]. Synthesis of the transition metal carbene complexes (palladium) was done by carbene transfer ftom the corresponding silver(I) complexes or by reaction with the metal acetate (nickel) [162] (see Figure 3.64). 

Abstract The synthesis, purification and characterization of ionic liquids is reviewed. The major synthetic routes to low melting ionic salts are described in detail. The intrinsic properties of ionic liquids make purification difficult and therefore a special emphasis is placed on currently employed purification methodologies. Synthetic methods which are designed to avoid specific impurities are also discussed. For the same reasons highlighted above characterization of ionic liquids presents unique challenges the available methods and some of the issues of their use are also reviewed. 

Schreiter ER, Stevens JE, Ortwerth MF (1999) Gold compounds as ionic liquids synthesis, structures, and thermal properties of n, n-diaUsylimidazolium tetrachloroaurate salts. Inorg Chem 38 3935-3940... 

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