ABSTRACT

Stable and metastable crystal phases of 1-butyl-3-methylimidazolium hexafluorophosphate were obtained in an adiabatic calorimeter providing precise temperature control during crystallization. Heat capacities, as well as temperatures and enthalpies of phase transitions, including fusion, were determined for three polymorphic sequences (I, II, and III). Structures of the crystal phases were assigned using crystallographic studies from the literature. The standard entropy of the liquid phase at T = 298.15 K determined using the calorimetric data for each sequence was the same within the uncertainty of the measurements. This, in combination with the crystallographic results, implies that the lowesttemperature crystal form is ordered for all sequences. The complete pattern of phase transformations in this ionic liquid at ambient pressure is described, and results show that the relative stability of Sequences II and III invert at T = 281 K.

Compounds

#	Formula	Name
1	C8H15F6N2P	1-butyl-3-methylimidazolium hexafluorophosphate

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	1	Triple point temperature, K ; Crystal			Crystal Liquid Gas	Adiabatic calorimetry	1
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Small (less than 1 g) adiabatic calorimetry	47
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Metastable crystal	Temperature, K; Metastable crystal	Pressure, kPa; Metastable crystal	Metastable crystal	Small (less than 1 g) adiabatic calorimetry	145
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Metastable crystal	Temperature, K; Metastable crystal	Pressure, kPa; Metastable crystal	Metastable crystal	Small (less than 1 g) adiabatic calorimetry	111
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Metastable crystal	Temperature, K; Metastable crystal	Pressure, kPa; Metastable crystal	Metastable crystal	Small (less than 1 g) adiabatic calorimetry	22
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Metastable crystal	Temperature, K; Metastable crystal	Pressure, kPa; Metastable crystal	Metastable crystal	Small (less than 1 g) adiabatic calorimetry	4
POMD	1	Molar enthalpy, kJ/mol ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid	Small (less than 1 g) adiabatic calorimetry	1
POMD	1	Molar enthalpy, kJ/mol ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid	Small (less than 1 g) adiabatic calorimetry	1
POMD	1	Molar enthalpy, kJ/mol ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid	Small (less than 1 g) adiabatic calorimetry	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Calorimetric study of polymorphism in 1-butyl-3-methylimidazolium hexafluorophosphate

Paulechka, E.[Eugene], Liavitskaya, T.[Tatsiana], Blokhin, A. V.[Andrey V.]

ABSTRACT