Properties of mono-protic ionic liquids composed of hexylammonium and hexylethylenediaminium cations with trifluoroacetate and bis (trifluoromethylsulfonyl) imide anions

Abstract

Protic ionic liquids (PILs) composed of hexylammonium (HHexam+) and hexylethylenediaminium (HHexen+) cations with trifluoroacetate (TFA−) and bis (trifluoromethylsulfonyl)imide (Tf2N−) anions forming HHexam(TFA), HHexam(Tf2N) and HHexen(Tf2N) were synthesized. The melting temperatures are 18.7 °C, 18.3 °C and 57.4 °C for HHexam(Tf2N),HHexen(Tf2N) and HHexam(TFA), respectively. The decompositions occurred at 327.5 °C, 322.3 °C and 216.9 °C for HHexen(Tf2N), HHexam(Tf2N) and HHexam(TFA), respectively. Physicochemical properties such as density, dynamic viscosity and electric conductivity of the PILs were studied in the temperature range of T = (298.15 to 353.15) K. Temperature dependence of the dynamic viscosity and the electric conductivity almost follows the Arrhenius equation for all the PILs. The relationship between the molar conductivity and the fluidity was described using the Walden rule. The Walden lines for all the PILs lie below and are close to the ideal KCl line.