Deep Eutectic Solvents Formed between Choline Chloride and Carboxylic Acids: Versatile Alternatives to Ionic Liquids
01 Jul 2004-Journal of the American Chemical Society (American Chemical Society)-Vol. 126, Iss: 29, pp 9142-9147
TL;DR: It is shown that the conductivity and viscosity of these liquids is controlled by ion mobility and the availability of voids of suitable dimensions, and this is consistent with the fluidity of other ionic liquids and molten salts.
Abstract: Deep Eutectic Solvents (DES) can be formed between a variety of quaternary ammonium salts and carboxylic acids. The physical properties are significantly affected by the structure of the carboxylic acid but the phase behavior of the mixtures can be simply modeled by taking account of the mole fraction of carboxylic acid in the mixture. The physical properties such as viscosity, conductivity, and surface tension of these DES are similar to ambient temperature ionic liquids and insight into the cause of these properties is gained using hole-theory. It is shown that the conductivity and viscosity of these liquids is controlled by ion mobility and the availability of voids of suitable dimensions, and this is consistent with the fluidity of other ionic liquids and molten salts. The DES are also shown to be good solvents for metal oxides, which could have potential application for metal extraction.
Citations
More filters
3,909 citations
TL;DR: All works discussed in this review aim at demonstrating that Deep Eutectic Solvents not only allow the design of eco-efficient processes but also open a straightforward access to new chemicals and materials.
Abstract: Within the framework of green chemistry, solvents occupy a strategic place. To be qualified as a green medium, these solvents have to meet different criteria such as availability, non-toxicity, biodegradability, recyclability, flammability, and low price among others. Up to now, the number of available green solvents are rather limited. Here we wish to discuss a new family of ionic fluids, so-called Deep Eutectic Solvents (DES), that are now rapidly emerging in the current literature. A DES is a fluid generally composed of two or three cheap and safe components that are capable of self-association, often through hydrogen bond interactions, to form a eutectic mixture with a melting point lower than that of each individual component. DESs are generally liquid at temperatures lower than 100 °C. These DESs exhibit similar physico-chemical properties to the traditionally used ionic liquids, while being much cheaper and environmentally friendlier. Owing to these remarkable advantages, DESs are now of growing interest in many fields of research. In this review, we report the major contributions of DESs in catalysis, organic synthesis, dissolution and extraction processes, electrochemistry and material chemistry. All works discussed in this review aim at demonstrating that DESs not only allow the design of eco-efficient processes but also open a straightforward access to new chemicals and materials.
3,325 citations
TL;DR: Based on the results the novel NADES may be expected as potential green solvents at room temperature in diverse fields of chemistry.
1,614 citations
Cites background or result from "Deep Eutectic Solvents Formed betwe..."
...…ILs and DES and extend their applications, apart from synthetic compounds, attention has directed towards natural products such as organic acids (Abbott et al., 2004; Gore et al., 2011; Fukaya et al., 2007) , amino acids (Fukumoto et al., 2005), sugars (Poletti et al., 2007; Imperato et al.,…...
[...]
...The creating DES was demonstrated for mixtures of quaternary ammonium salts (Abbott et al., 2003) with a range of amides and carboxylic acids (Abbott et al., 2004), and later extended to choline chloride with alcohols (Gorke et al., 2008), and urea with sugars or organic acids (Imperato et al.,…...
[...]
...These observations lead to our conclusion that one chloride ion from choline chloride can form two hydrogen bonds with two hydroxyl groups from sugars, thus behaving similarly as in a mixture of a choline chloride and a carboxylic acid (Abbott et al., 2004)....
[...]
...In the case of DES, previous studies have reported that most of them were not liquid at room temperature (Abbott et al., 2003; 2004; Imperato et al., 2005) and consequently there is a limitation for their application as extraction or reaction media at room temperature....
[...]
TL;DR: In this paper, a survey on the latest most representative developments and progress concerning ionic liquids, from their fundamental properties to their applications in catalytic processes, is presented, highlighting their emerging use for biomass treatment and transformation.
Abstract: This review gives a survey on the latest most representative developments and progress concerning ionic liquids, from their fundamental properties to their applications in catalytic processes. It also highlights their emerging use for biomass treatment and transformation.
1,471 citations
TL;DR: Deep Eutectic Solvents (DES) as discussed by the authors are a class of solvents that can be defined as a mixture of two or more components, which at a particular composition present a high melting point depression becoming liquids at room temperature.
Abstract: Green technology actively seeks new solvents to replace common organic solvents that present inherent toxicity and have high volatility, leading to evaporation of volatile organic compounds to the atmosphere. Over the past two decades, ionic liquids (ILs) have gained enormous attention from the scientific community, and the number of reported articles in the literature has grown exponentially. Nevertheless, IL “greenness” is often challenged, mainly due to their poor biodegradability, biocompatibility, and sustainability. An alternative to ILs are deep eutectic solvents (DES). Deep eutectic solvents are defined as a mixture of two or more components, which may be solid or liquid and that at a particular composition present a high melting point depression becoming liquids at room temperature. When the compounds that constitute the DES are primary metabolites, namely, aminoacids, organic acids, sugars, or choline derivatives, the DES are so called natural deep eutectic solvents (NADES). NADES fully represen...
1,439 citations
References
More filters
TL;DR: There are indications that switching from a normal organic solvent to an ionic liquid can lead to novel and unusual chemical reactivity, which opens up a wide field for future investigations into this new class of solvents in catalytic applications.
Abstract: Ionic liquids are salts that are liquid at low temperature (<100 degrees C) which represent a new class of solvents with nonmolecular, ionic character. Even though the first representative has been known since 1914, ionic liquids have only been investigated as solvents for transition metal catalysis in the past ten years. Publications to date show that replacing an organic solvent by an ionic liquid can lead to remarkable improvements in well-known processes. Ionic liquids form biphasic systems with many organic product mixtures. This gives rise to the possibility of a multiphase reaction procedure with easy isolation and recovery of homogeneous catalysts. In addition, ionic liquids have practically no vapor pressure which facilitates product separation by distillation. There are also indications that switching from a normal organic solvent to an ionic liquid can lead to novel and unusual chemical reactivity. This opens up a wide field for future investigations into this new class of solvents in catalytic applications.
5,387 citations
TL;DR: A series of hydrophilic and hydrophobic 1-alkyl-3-methylimidazolium room temperature ionic liquids (RTILs) have been prepared and characterized to determine how water content, density, viscosity, surface tension, melting point, and thermal stability are affected by changes in alkyl chain length and anion.
3,469 citations
TL;DR: In this article, a table of donnees (pour de nombreux solvants) des valeurs des parametres M*, α and β donnant respectivement la polarisabilite du solvant, son pouvoir de donneur de proton, and d'accepteur de protons dans les liaisons hydrogene solute-solvant
Abstract: Table de donnees (pour de nombreux solvants) des valeurs des parametres M*, α et β donnant respectivement la polarisabilite du solvant, son pouvoir de donneur de proton, et d'accepteur de protons dans les liaisons hydrogene solute-solvant
3,161 citations
TL;DR: The phase behavior of a variety of quaternary ammonium halides/ZnCl(2) mixtures is characterized and it is shown that the depression of freezing point is related to the increase in size of the component ions.
Abstract: The synthesis of ionic liquids based upon functionalized quaternary ammonium salts and metal salts of zinc, tin, or iron is demonstrated. The freezing point of these ionic liquids was studied as a function of the quaternary ammonium cation. The complex anions were identified and quantified using mass spectrometry and potentiometry. It is shown that the primary zinc anion is Zn2Cl5- with Zn3Cl7- becoming more abundant in more Lewis basic solutions. Similar results were observed for ionic liquids containing SnCl2. The surface tension was also measured and was used to explain the high viscosity of the ionic liquids in terms of the large ion:hole size ratio and the small probability of finding a hole of suitable dimensions adjacent to a given ion to permit movement. The phase behavior of a variety of quaternary ammonium halides/ZnCl2 mixtures is characterized and it is shown that the depression of freezing point is related to the increase in size of the component ions.
300 citations
TL;DR: It is shown that chromium can be electrodeposited efficiently to yield a crack-free deposit and this approach could circumvent the use of chromic acid for chromium electroplating, which would be a major environmental benefit.
Abstract: A dark green, viscous liquid can be formed by mixing choline chloride with chromium(III) chloride hexahydrate and the physical properties are characteristic of an ionic liquid. The eutectic composition is found to be 1:2 choline chloride/chromium chloride. The viscosity and conductivity are measured as a function of temperature and composition and explained in terms of the ion size and liquid void volume. The electrochemical response of the ionic liquid is also characterised and it is shown that chromium can be electrodeposited efficiently to yield a crack-free deposit. This approach could circumvent the use of chromic acid for chromium electroplating, which would be a major environmental benefit. This method of using hydrated metal salts to form ionic liquids is shown to be valid for a variety of other salt mixtures with choline chloride.
286 citations