Is ethaline a deep eutectic solvent?

Abstract

The ethaline composition lies in the ChCl-saturated region of the phase diagram which explains why ChCl precipitates in this solvent.

The eutectic point in choline chloride and ethylene glycol mixtures

“…In summary, we show that the eutectic melt of ChCl:EG is at −28 o C, corroborating recent work of Agieienko and Buchner, 22 , and that the eutectic composition is constrained to 0.01 < x ChCl < 0.02. These values do not coincide with those reported by Shahbaz et al 14 at −66 o C and 1:2 ChCl:EG, and more generally our study of ChCl:EG mixtures using DSC highlights the importance of careful separation of thermodynamic and kinetic transitions near eutectic points.…”

“…1 Summary of previously reported temperature-composition (mole fraction of ChCl, x ChCl = 1 − x EG ) phase behaviour for the ChCl:EG system. Ibrahim et al 20 -yellow triangle; Crespo et al 21 -green dashed line; Agieienko and Buchner 22 -magenta triangles and circles highlight the solidus and liquidus lines, respectively; Silva et al 5 -orange diamonds; Shahbaz et al 14 -black circles; Jani et al 23 -cyan circle. Ideal solution liquidus lines calculated for ethylene glycol (cyan solid line) and choline chloride (red solid line) using Equation 1.…”

Design of Deep Eutectic Systems: Plastic Crystalline Materials as Constituents

“…ChCl-based eutectic systems containing diols, such as ChCl/ethylene glycol, have been studied extensively [ 18 , 47 , 48 , 49 , 50 ]. Owing to the low melting temperature and slightly negative deviation from the ideal behavior of most diols, a small depression at the eutectic point is observed in ChCl-based eutectic systems containing diols [ 18 , 51 , 52 ]. In this work, neopentyl glycol, which possesses a high melting temperature, was mixed with ChCl.…”

Holding it together: noncovalent cross-linking strategies for ionogels and eutectogels

“…Best practice would be to also include the raw data, such as differential scanning calorimetry (DSC) scans, that led to the proposed phase diagram. 50,51 Repeatable DSC measurements on DESs can be challenging to obtain, however, due to the tendency of DESs to exhibit substantial supercooling. 52 Indeed, one system that was widely accepted as being a ''true DES'' for many years (a 2 : 1 molar ratio of ethylene glycol (EG) : choline chloride, EG : ChCl (2 : 1), or ethaline) was recently shown to have a very different actual eutectic mixture stoichiometry and a nearly ideal melting point depression upon performing a careful DSC study.…”

“…52 Indeed, one system that was widely accepted as being a ''true DES'' for many years (a 2 : 1 molar ratio of ethylene glycol (EG) : choline chloride, EG : ChCl (2 : 1), or ethaline) was recently shown to have a very different actual eutectic mixture stoichiometry and a nearly ideal melting point depression upon performing a careful DSC study. 50 Nevertheless, the ethaline mixture has been among the most popular for forming eutectogels to date, likely due to its low viscosity and high room temperature ionic conductivity as compared to other DESs. 8 The vast majority of reported DESs are water-miscible, although the development of ''hydrophobic DESs'' has also been championed in recent years.…”