Can cholinium chloride form eutectic solvents with organic chloride-based salts?


The high melting point of a large number of organic salts with potential ionic liquid-like properties, hinders their applicability as solvents. Considering the success of cholinium chloride on lowering the melting temperature of several substances and its success on forming deep eutectic solvents, this work studies its mixing with organic chlorides to lower their melting points producing eutectic ionic liquids. The solid-liquid phase diagrams for binary mixtures composed of cholinium chloride and ten organic halides were experimentally measured. Surprisingly, cholinium chloride presented, for all these systems, significant positive deviations from ideal liquid behaviour that restricted its ability to lower the melting points of these mixtures. Only for mixtures with ammonium chloride, tetramethylammonium chloride, bis(2-hydroxyethyl)dimethylammonium chloride or cholinium bromide was cholinium chloride able to significantly lower the melting point of the mixture, but without reaching values close to room temperature (298 K). For a better understanding of the results obtained, the solid-liquid phase diagrams of four alkylammonium chloride-based mixtures were experimentally assessed and used to show that these compounds are better than cholinium chloride at inducing negative deviations from ideality, leading to greater melting point depressions. (C) 2019 Elsevier B.V. All rights reserved.



subject category

Thermodynamics; Chemistry; Engineering


Abranches, DO; Silva, LP; Martins, MAR; Fernandez, L; Pinho, SP; Coutinho, JAP

our authors


This work was developed in the scope of the project CICECO - Aveiro Institute of Materials, POCI-01-0145-FEDER-007679 (Ref. FCT UID/CTM/50011/2013) and Associate Laboratory LSRE-LCM, POCI-01-0145-FEDER-006984 (Ref. FCT UID/EQU/50020/2019), and project MultiBiorefinery (POCI-01-0145-FEDER-016403), all financed by national funds through the FCT/MCTES (PIDDAC) and when appropriate co-financed by FEDER under the PT2020 Partnership Agreement. FO' is also acknowledged for funding the project DeepBiorefinery (PTDC/AGRTEC/1191/2014). The authors acknowledge the European Research Council under the European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement no. 337753. M.A.R.M. acknowledges financial support from NORTE-01-0145-FEDER-000006 - funded by NORTE2020 through PT2020 and ERDF. L.P.S. acknowledges FCT for her PhD grant (SFRH/BD/135976/2018).

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