ABSTRACT

The thermal behavior, solid and liquid heat capacities of the 1-benzyl-3-methylimidazolium, [Bzmim]+, based ionic liquid series with Cl-, PF6-, BF4-, CHF2CF2SO3- and NTf2- as anions were used to evaluate the effect of the insertion of an aromatic character (benzyl group) and the expected increase of the p p interactions as well as the impact in the cation anion hindrance and charge delocalization in the ionic liquid properties. It was found that the molar liquid heat capacities of [Bzmim][X] are in the same order as the 1-pentyl-3-methylimidazolium, [C5C1im][X] analogs. A good correlation between the molar (solid and liquid) heat capacity and the number of atoms of the anion was found. Two different crystalline forms for [Bzmim][BF4] differing by 10 K in the melting temperature and about 10% in the heat capacity were found. The crystallization behavior, melting temperatures, and enthalpies and entropies of fusion show that the insertion of an aromatic character (benzyl group) in the imidazolium cation leads to a significant and systematic change of the thermophysical properties of the ionic liquids associated with an increase of the glass transition and melting temperatures arising from the additional p-p interactions.

Compounds

#	Formula	Name
1	C11H13ClN2	1-benzyl-3-methyl-1H-imidazolium chloride
2	C11H13BF4N2	1-benzyl-3-methylimidazolium tetrafluoroborate
3	C11H13F6N2P	1-benzyl-3-methylimidazolium hexafluorophosphate
4	C13H14F4N2O3S	1-benzyl-3-methylimidazolium 1,1,2,2-tetrafluoroethanesulfonate
5	C13H13F6N3O4S2	1-benzyl-3-methyl-1H-imidazol-3-ium bis((trifluoromethyl)sulfonyl)amide

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 ; Glass			Glass Liquid Air at 1 atmosphere	DSC	1
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Metastable liquid	Temperature, K; Metastable liquid Pressure, kPa; Metastable liquid		Metastable liquid	Drop calorimetry	1
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Small sample (50 mg) DSC	7
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Metastable liquid	Temperature, K; Metastable liquid	Pressure, kPa; Metastable liquid	Metastable liquid	Small sample (50 mg) DSC	17
POMD	2	Triple point temperature, K ; Glass			Glass Liquid Air at 1 atmosphere	DSC	1
POMD	2	Triple point temperature, K ; Metastable crystal			Metastable crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Triple point temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Metastable crystal			Metastable crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Metastable crystal	Temperature, K; Metastable crystal Pressure, kPa; Metastable crystal		Metastable crystal	Drop calorimetry	1
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal Pressure, kPa; Crystal		Crystal	Drop calorimetry	1
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Metastable crystal	Temperature, K; Metastable crystal	Pressure, kPa; Metastable crystal	Metastable crystal	Small sample (50 mg) DSC	10
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Small sample (50 mg) DSC	15
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Metastable liquid	Temperature, K; Metastable liquid	Pressure, kPa; Metastable liquid	Metastable liquid	Small sample (50 mg) DSC	4
POMD	3	Triple point temperature, K ; Glass			Glass Liquid Air at 1 atmosphere	DSC	1
POMD	3	Triple point temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	3	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	3	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal Pressure, kPa; Crystal		Crystal	Drop calorimetry	1
POMD	3	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Small sample (50 mg) DSC	20
POMD	4	Triple point temperature, K ; Glass			Glass Liquid Air at 1 atmosphere	DSC	1
POMD	4	Triple point temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	4	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	4	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal Pressure, kPa; Crystal		Crystal	Drop calorimetry	1
POMD	4	Molar heat capacity at constant pressure, J/K/mol ; Metastable liquid	Temperature, K; Metastable liquid Pressure, kPa; Metastable liquid		Metastable liquid	Drop calorimetry	1
POMD	4	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	Small sample (50 mg) DSC	4
POMD	4	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Small sample (50 mg) DSC	5
POMD	5	Triple point temperature, K ; Glass			Glass Liquid Air at 1 atmosphere	DSC	1
POMD	5	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid Pressure, kPa; Liquid		Liquid	Drop calorimetry	1
POMD	5	Molar heat capacity at constant pressure, J/K/mol ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Small sample (50 mg) DSC	20

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Phase behavior and heat capacities of the 1-benzyl-3-methylimidazolium ionic liquids

Serra, P. B. P.[Paulo B. P.], Ribeiro, F. M. S.[Filipe M. S.], Rocha, M. A. A.[Marisa A. A.], Fulem, M.[Michal], Ruzicka, K.[Kvetoslav], Santos, L. M. N. B. F.[Luis M. N. B. F.]

ABSTRACT