Deep Eutectic Solvents (DESs) and Their Applications

Smith, Emma L.; Abbott, Andrew P.; Ryder, Karl S.

doi:10.1021/cr300162p

Cited by 5,052 publications

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References 243 publications

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“…DESs are generally prepared by the self‐association of hydrogen‐bond donors (HBD) and hydrogen‐bond acceptors (HBA), which form a liquid driven by strong hydrogen‐bonding interactions that reduce the ability of the parent compounds to crystallize (Figure 1 a) 28, 29. Generally, a DES is obtained by mixing a quaternary ammonium halide salt with a neutral organic HBD to form a complex with halide ions and solvent molecules 30, 31, 32. DESs exhibit several advantages, such as easy and cheap fabrication, no need for purification, and insensitivity to water, and have been widely accepted.…”

Section: Introductionmentioning

confidence: 99%

Efficient Cleavage of Lignin–Carbohydrate Complexes and Ultrafast Extraction of Lignin Oligomers from Wood Biomass by Microwave‐Assisted Treatment with Deep Eutectic Solvent

et al. 2017

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Lignocellulosic biomass is an abundant and renewable resource for the production of biobased value‐added fuels, chemicals, and materials, but its effective exploitation by an energy‐efficient and environmentally friendly strategy remains a challenge. Herein, a facile approach for efficiently cleaving lignin–carbohydrate complexes and ultrafast fractionation of components from wood by microwave‐assisted treatment with deep eutectic solvent is reported. The solvent was composed of sustainable choline chloride and oxalic acid dihydrate, and showed a hydrogen‐bond acidity of 1.31. Efficient fractionation of lignocellulose with the solvent was realized by heating at 80 °C under 800 W microwave irradiation for 3 min. The extracted lignin showed a low molecular weight of 913, a low polydispersity of 1.25, and consisted of lignin oligomers with high purity (ca. 96 %), and thus shows potential in downstream production of aromatic chemicals. The other dissolved matter mainly comprised glucose, xylose, and hydroxymethylfurfural. The undissolved material was cellulose with crystal I structure and a crystallinity of approximately 75 %, which can be used for fabricating nanocellulose. Therefore, this work promotes an ultrafast lignin‐first biorefinery approach while simultaneously keeping the undissolved cellulose available for further utilization. This work is expected to contribute to improving the economics of overall biorefining of lignocellulosic biomass.

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Section: Introductionmentioning

confidence: 99%

Efficient Cleavage of Lignin–Carbohydrate Complexes and Ultrafast Extraction of Lignin Oligomers from Wood Biomass by Microwave‐Assisted Treatment with Deep Eutectic Solvent

et al. 2017

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“…The physicochemical properties of DESs are related to those of ionic liquids and their mixtures;2 DESs are hybrid systems where molecular ionic clusters are found within a complex and disordered hydrogen‐bonding network 3. This nanostructure can be adjusted by selection of the mixing ratio and molecular chemical moieties,4 and this additional degree of design freedom has aided the development of DESs as “greener” alternative media for organic and inorganic synthesis,5 electrochemistry, separation, extraction, and biotransformations 6…”

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The Effect of Water upon Deep Eutectic Solvent Nanostructure: An Unusual Transition from Ionic Mixture to Aqueous Solution

2017

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The nanostructure of a series of choline chloride/urea/water deep eutectic solvent mixtures was characterized across a wide hydration range by neutron total scattering and empirical potential structure refinement (EPSR). As the structure is significantly altered, even at low hydration levels, reporting the DES water content is important. However, the DES nanostructure is retained to a remarkably high level of water (ca. 42 wt % H2O) because of solvophobic sequestration of water into nanostructured domains around cholinium cations. At 51 wt %/83 mol % H2O, this segregation becomes unfavorable, and the DES structure is disrupted; instead, water–water and DES–water interactions dominate. At and above this hydration level, the DES–water mixture is best described as an aqueous solution of DES components.

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“…As the immersion coating of Au is dependent on the efficient removal of Ni from the surface, these plating solutions are typically run at an acidic pH which means the conventional aqueous immersion gold process fundamentally contributes to the formation of these defects and control over when and where they form is difficult. 14 To address these issues, Deep Eutectic Solvents (DES) have shown promise in the immersion coating of other metals, such as copper, from acid free formulations [15][16][17] and so our strategy has been focused on the development of alternative processes using DES media.…”

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confidence: 99%

“…18 These liquids have widespread appeal in the electrochemical, synthetic and polymer fields due to their low toxicity, they are air and moisture stable and are easily prepared in high purity. 15 We have previously demonstrated a variety of electrolytic coatings including Ni, 19 Cu, Cr, Ag, Sn and Zn at high current efficiency. 20 In addition, an immersion Ag deposition onto copper 10 as an alternative PCB surface finish was studied, including scale up to pilot plant scale, demonstrating its suitability for the industrial production of PCBs.…”

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Electrochemistry and speciation of Au⁺in a deep eutectic solvent: growth and morphology of galvanic immersion coatings

Ballantyne

Forrest

Frisch

et al. 2015

Phys. Chem. Chem. Phys.

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In this study we compare the electrochemical and structural properties of three gold salts AuCl, AuCN and KAu(CN)2 in a Deep Eutectic Solvent (DES) electrolyte (Ethaline 200) in order to elucidate factors affecting the galvanic deposition of gold coatings on nickel substrates. A chemically reversible diffusion limited response was observed for AuCl, whereas AuCN and KAu(CN)2 showed much more complicated, kinetically limited responses. Galvanic exchange reactions were performed on nickel substrates from DES solutions of the three gold salts; the AuCN gave a bright gold coating, the KAu(CN)2 solution give a visibly thin coating, whilst the coating from AuCl was dull, friable and poorly adhesive. This behaviour was rationalised by the differing speciation for each of these compounds, as evidenced by EXAFS methods. Analysis of EXAFS data shows that AuCl forms the chlorido-complex [AuCl2] − , AuCN forms a mixed [AuCl(CN)] − species, whereas KAu(CN)2 maintains its [Au(CN)2] − structure. The more labile Cl − enables easier reduction of Au when compared to the tightly bound cyanide species, hence leading to slower kinetics of deposition and differing electrochemical behaviour. We conclude that metal speciation in DESs is a function of the initial metal salt and that this has a strong influence on the mechanism and rate of growth, as well as on the morphology of the metal deposit obtained. In addition, these coatings are also extremely promising from a technological perspective as Electroless Nickel Immersion Gold (ENIG) finishes in the printed circuit board (PCB) industry, where the elimination of acid in gold plating formulation could potentially lead to more reliable coatings. Consequently, these results are both significant and timely. IntroductionGold plating processes are widely used in the materials finishing, decorative and electronics industries due to their high reliability, electrical conductivity and corrosion resistance. 1 The key characteristic feature of these noble metal coatings is the lack of insulating surface oxides. 2 Electrolytic, 3 electroless, 4 and immersion plating 5 are the three common electrochemical methods used for the coating of conducting substrates with gold films. In each of these processes the conventional/commercial plating bath chemistry is dominated by the choice of the dicyanidoaurate anion [Au(CN) 2 ] − as the gold source 6 due to its high stability 7 and the ability to yield fine grained deposits. 8 In electroplating experiments, acidic plating baths around pH 5 are used to produce soft gold coatings, whilst alkaline and neutral baths are used to produce hard gold. 8 However, there are significant safety concerns, as well as issues regarding the disposal of waste, where cyanide based processes are present. In addition, the requirement of large negative reduction potentials can also lead to the coreduction of hydrogen ions. 9 As such, there have been cyanide free gold plating solutions developed, primarily based upon sulphite and thiosulfate complexes, however these are limited to...

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Deep Eutectic Solvents (DESs) and Their Applications

Cited by 5,052 publications

References 243 publications

Efficient Cleavage of Lignin–Carbohydrate Complexes and Ultrafast Extraction of Lignin Oligomers from Wood Biomass by Microwave‐Assisted Treatment with Deep Eutectic Solvent

Efficient Cleavage of Lignin–Carbohydrate Complexes and Ultrafast Extraction of Lignin Oligomers from Wood Biomass by Microwave‐Assisted Treatment with Deep Eutectic Solvent

The Effect of Water upon Deep Eutectic Solvent Nanostructure: An Unusual Transition from Ionic Mixture to Aqueous Solution

Electrochemistry and speciation of Au⁺in a deep eutectic solvent: growth and morphology of galvanic immersion coatings

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Deep Eutectic Solvents (DESs) and Their Applications

Cited by 5,052 publications

References 243 publications

Efficient Cleavage of Lignin–Carbohydrate Complexes and Ultrafast Extraction of Lignin Oligomers from Wood Biomass by Microwave‐Assisted Treatment with Deep Eutectic Solvent

Efficient Cleavage of Lignin–Carbohydrate Complexes and Ultrafast Extraction of Lignin Oligomers from Wood Biomass by Microwave‐Assisted Treatment with Deep Eutectic Solvent

The Effect of Water upon Deep Eutectic Solvent Nanostructure: An Unusual Transition from Ionic Mixture to Aqueous Solution

Electrochemistry and speciation of Au+in a deep eutectic solvent: growth and morphology of galvanic immersion coatings

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Electrochemistry and speciation of Au⁺in a deep eutectic solvent: growth and morphology of galvanic immersion coatings