New hydrophobic ionic liquids with perfluoroalkyl phosphate and cyanofluoroborate anions

Novel hydrophobic ionic liquids (ILs) with tris(perfluoroalkyl)trifluorophosphate anions (e.g. [(C2F5)(3)PF3](-); FAP anion), the bis[bis(pentafluoroethyl)phosphinyl]imide (FPI) anion, the tetracyanoborate (TCB) anion, the tricyanofluoroborate (MFB) anion and the dicyanodifluoroborate (DDB) anion have been developed. The properties of these ionic liquids, i.e. their thermal and electrochemical stabilities as well as their viscosities, densities and refractive indices were studied and will be discussed. FAP ionic liquids are more hydrolytically stable and less viscous compared to ionic liquids with the hexafluorophosphate ([PF6](-)) anion. The hydrophobicity of ionic liquids with the cyano- and fluoroborate anions [BFx(CN)(4-x)](-) (x = 0-4) strongly decrease in the order: EMIM[B(CN)(4)] > EMIM[BF(CN)(3)] > EMIM[BF2(CN)(2)] > EMIM[BF3(CN)] similar to EMIM[BF4]; EMIM[BF3(CN)] as well as EMIM[BF4] are miscible with water. The lowest viscosity for all ionic liquids composed of the EMIM cation and weakly coordinating anions as the ones presented herein was observed for EMIM[BF2(CN)(2)] (11.1 mPa.s at 20 degrees C). (C) 2015 Elsevier B.V. All rights reserved.