Thermal behaviour of triethanolammonium halides

Synthesis and properties of triethanolamine-based salts with mineral and organic acids as protic ionic liquids

Abstract: Seven triethanolammonium (tris(2-hydroethyl)ammonium)-based protic ionic liquids (PILs) and three molten salts were synthesized by proton transfer reaction from carboxylic and inorganic acids to triethanolamine (TEOA). The PILs were characterized by 1 H NMR, 13 C NMR, 1 H/ 15 N NMR and FT-IR spectroscopic methods. The thermal behavior of the synthesized PILs was studied, as well as the temperature dependence of their electric conductivity, viscosity, and their electrochemical stability window (ECW). The melting temperature (T m ) of the salts obtained in this work and of most of the TEOA salts with organic acids reported in literature is within the range of 313–373 °C. T m of most PILs with inorganic acids is higher than 100 °C, besides, they have a narrow temperature range in liquid state. At the temperatures > 90 °C, triethanolammonium trifluoroacetate and nitrate have the highest electric conductivity values (~ 10 − 2 Ohm − 1 ∙ cm − 1 ). For the PILs synthesized in this work, just like for TEOA with sulfonic acids, a temperature increase leads to the ECW reduction. The triethanolammonium sulphate salt is the least sensitive to the temperature increase, while in the other PILs the temperature increase from 50 °С to 120 С makes the ECW 1.4–1.6 times narrower.

Thermal properties of protic ionic liquids derivatives triethanolamine-based salts of mineral and organic acids

Abstract: Phase behavior of twenty-one synthesized salts of triethanolammonium(tris (2-hydroethyl)ammonium) has been studied by the methods of differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). It has been established that 18 of them are protic ionic liquids (PILs) with Tm 100 °C. The PILs have been divided into three groups according to their phase behavior in the DSC experiment. The phase behavior of each of the studied ionic liquids has been analyzed. Multiple regression has been obtained between the ionic liquids characteristics (such as melting, glass transition and decomposition temperatures) determined experimentally and the properties of the anions of the acids forming the PILs calculated by the quantum chemistry methods. It has been shown that there is a linear compensation effect between the changes in the entropy and enthalpy caused by triethanolammonium salts melting.