Refractive index and heat capacity of 1-butyl-3-methylimidazolium bromide and 1-butyl-3-methylimidazolium tetrafluoroborate, and vapor pressure of binary systems for 1-butyl-3-methylimidazolium bromide plus trifluoroethanol and 1-butyl-3-methylimidazolium tetrafluoroborate plus trifluoroethanol

1-Butyl-3-methylimidazoliumtetrafluoroborate ([BMIm][BF4]) + 2,2,2-trifluoroethanol (TFE) and 1-butyl-3-methylimidazolium bromide ([BMIm][Br]) + TFE mixtures exhibit properties which render them suitable as candidates for working fluids in absorption heat pumps or chillers. Refractive indices and heat capacities of each pure ionic liquid were investigated in the temperature range of 298.2-323.2 K. Vapor pressures were measured by using the boiling point method in the concentration range of 40.0-90.0 mass% of ionic liquid and were correlated with an Antoine-type equation. The average absolute deviations between experimental and calculated values were 0.6% for the [BMIm][BF4] + TFE and 0.4% for the [BMIm] [Br] + TFE system, respectively. (C) 2004 Elsevier B.V. All rights reserved.