Synthesis and Physical Properties of Tunable Aryl Alkyl Ionic Liquids (TAAILs)

Tunable aryl alkyl ionic liquids (TAAILs) based on the imidazolium cation were first reported in 2009. Since then, a series of TAAILs with different properties due to the electron‐donating or ‐withdrawing effect of the substituents at the aryl ring has been developed. Herein, a wide variety of those ionic liquids (ILs) is presented in terms of their cation structure. The authors synthesized ILs containing the bromide or bis(trifluoromethane)sulfonimide anion and 1‐aryl‐3‐alkyl imidazolium cations with various substituents in the ortho and/ or para position of the phenyl ring and alkyl chains of different lengths varying from butyl to dodecyl. The differences of their physical properties (melting point, thermal decomposition, viscosity, electro‐chemical window) of these ILs are reported according to their structure.
Different 1‐aryl‐3‐alkyl imidazolium ionic liquids (tunable aryl alkyl ionic liquids, TAAILs) with electron withdrawing and electron donating substituents on the phenyl ring of the cation, various alkyl chain lengths and the bis(trifluoromethane)sulfonimide (LiNTf2) anion have been prepared. Their physical properties, such as melting points, thermal decomposition, viscosity and electrochemical window, are described to give a broad overview of this class of organic salts.