ABSTRACT

A systematic study of densities and refractive indices of 17 room temperature ionic liquids is presented at four different temperatures ranging from 293 K to 333 K. The ionic liquids are grouped into four families: 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, [Cnmim][Ntf2], ionic liquids (with n = 2, 4, 6, 8, 10, 12, and 14); 1-alkyl-3-methylimidazolium hexafluorophosphate, [Cnmim][PF6], ionic liquids (with n = 4, 6, 8); ionic liquids based on the trihexyl(tetradecyl)phosphonium cation, [P6 6 6 14], combined with the anions bis(trifluoromethylsulfonyl)amide, [Ntf2], acetate, [OAc], and triflate, [OTf]; and [C4mim]-based ionic liquids combined with the anions [OAc], [OTf], methylsulfate [MeSO4], and tetrafluoroborate [BF4]. The data obtained were analysed to determine the effect of (i) temperature, (ii) the alkyl chain length of the 1-alkyl-3-methylimidazolium cation, and (iii) the nature of the anion. Different empirical models for the calculation of the densities of the ionic liquids were tested. Molar refractions were also calculated from the volumetric and refractive index data and the values were discussed with the aim of checking their utility in obtaining insights on the intermolecular forces and behaviour in solution of the different ionic liquids.

Compounds

#	Formula	Name
1	C8H11F6N3O4S2	1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide
2	C10H15F6N3O4S2	1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide
3	C12H19F6N3O4S2	1-hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide
4	C14H23F6N3O4S2	1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide
5	C16H27F6N3O4S2	1-decyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide
6	C18H31F6N3O4S2	1-dodecyl-3-methyl-1H-imidazolium bis(trifluoromethylsulfonyl)amide
7	C20H35F6N3O4S2	1-tetradecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide
8	C34H68F6NO4PS2	trihexyl(tetradecyl)phosphonium bis[(trifluoromethyl)sulfonyl]imide
9	C34H71O2P	trihexyl(tetradecyl)phosphonium acetate
10	C8H15F6N2P	1-butyl-3-methylimidazolium hexafluorophosphate
11	C10H19F6N2P	1-hexyl-3-methylimidazolium hexafluorophosphate
12	C12H23F6N2P	1-octyl-3-methylimidazolium hexafluorophosphate
13	C9H18N2O4S	1-butyl-3-methylimidazolium methyl sulfate
14	C9H15F3N2O3S	1-butyl-3-methylimidazolium trifluoromethanesulfonate
15	C8H15BF4N2	1-butyl-3-methylimidazolium tetrafluoroborate
16	C10H18N2O2	1-butyl-3-methylimidazolium acetate
17	C33H68F3O3PS	trihexyltetradecylphosphonium 1,1,1-trifluoromethanesulfonate

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	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	1	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	2	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	2	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	3	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	3	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	4	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	4	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	5	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	5	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	6	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	6	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	7	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	2
POMD	7	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	2
POMD	8	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	8	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	9	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	9	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	10	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	10	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	11	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	11	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	12	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	12	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	13	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	13	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	14	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	14	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	15	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	15	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	16	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	16	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4
POMD	17	Mass density, kg/m3 ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Vibrating tube method	4
POMD	17	Refractive index (Na D-line) ; Liquid	Temperature, K; Liquid	Pressure, kPa; Liquid	Liquid	Standard Abbe refractometry	4

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Densities and refractive indices of imidazolium- and phosphonium-based ionic liquids: Effect of temperature, alkyl chain length, and anion

Tariq, M., Forte, P. A. S., Gomes, M. F. C., Lopes, J. N. C., Rebelo, L. P. N.

ABSTRACT