Estimates of internal pressure and molar refraction of imidazolium based ionic liquids as a function of temperature

摘要

Estimates of the internal pressure (partial derivative U/partial derivative V) (T) of the ionic liquids (ILs) 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF4], 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], and 1-methyl-3-octylimidazolium tetrafluoroborate [OMIM][BF4] were made from experimentally determined densities and speeds of sound in the temperature range 283.15 to 343.15 K. Values (partial derivative U/partial derivative V) (T) for all the ILs studied are higher than those of water and molecular organic liquids. We also measured the refractive indices n(D) in the temperature range 288.15 to 343.15 K and estimated the molar refraction R-M. Refractive indices of ILs were also higher than those of normal organic liquids but were comparable to those of long hydrocarbon chain organic solvents.