Physicochemical Properties of Hydrophobic Ionic Liquids Containing 1-Octylpyridinium, 1-Octyl-2-methylpyridinium, or 1-Octyl-4-methylpyridinium Cations

This paper reports the synthesis of some ionic liquids containing cations 1-octylpyridinium [OPYR] +, 1-octyl-2-methylpyridinium [2MOPYR] +, or 1-octyl-4-methylpyridinium [4MOPYR] + and anions dicyanamide [N(CN) 2 ] -, bis(trifluoromethylsulfonyl)imide [Tf 2 N] -, bis(pentafluoroethylsulfonyl)imide [BETI] -, trifluoromethyl sulfonate [TfO] -, nonafluorobutyl sulfonate [NfO] -, tetrafluoroborate [BF 4 ] -, trifluorophenylborate [BF 3 Ph] -, tetraphenylborate [BPh 4 ] -, or hexafluoroarsenate [AsF 6 ] - . Melting points, decomposition temperatures, densities, mutual solubilities with water, and viscosities have been measured. Unlike similar ionic liquids containing imidazolium cations, pyridinium ionic liquids studied here are nearly immiscible with water. Viscosities are similar, and water contents are slightly lower than those for ionic liquids containing imidazolium cations.