Low-temperature heat capacity and the thermodynamic functions of a novel ether-based ionic liquid 1-(2-ethoxyethyl)-3-ethylimidazolium thiocyanate

Abstract

A novel ionic liquid (IL) modified by ether was prepared by a two-step synthesis method for the first time in this paper. The structure of 1-(2-ethoxyethyl)-3-ethylimidazolium thiocyanate ([C₂2O2Im][SCN]) was characterized and analyzed by hydrogen nuclear magnetic resonance (¹H-NMR), carbon nuclear magnetic resonance (¹³C-NMR), Fourier transform infrared spectroscopy (FT-IR), electrospray ionization-mass spectrometry (ESI-MS), elemental analysis and thermal gravity analysis (TG). Within a specific temperature range from 79 to 393 K, the low temperature heat capacity of [C₂2O2Im][SCN] was determined, using a high precision low temperature adiabatic calorimeter. Then, the related thermodynamic functions, such as (H_T − H_298.15), (S_T − S_298.15) and (G_T − G_298.15), were calculated, which can provide a theoretical basis for the application of ether-based ILs in the future.