Liquid Analogues Research Articles

New levulinic acid-based deep eutectic solvents: Synthesis and physicochemical property determination

Recently, deep eutectic solvents (DESs) have emerged as new and inexpensive ionic liquids (ILs) analogues. They possess attractive and similar solvent properties with traditional ILs. In present work a serials of DESs were prepared by pairing renewable levulinic acid (LA) as hydrogen donor with seven quarternary ammonium salts as hydrogen acceptor. The samples were further characterized in the temperature ranging from 293.15 to 333.15K at atmospheric pressure with the results of density (0.99891–1.17735gcm−3), dynamic viscosity (12.70–376.50mPas), electrical conductivity (0.35–8.27mScm−1), and refractive index data (1.44384–1.47273). The temperature dependence of these properties was explored and correlated with simple linear or Vogel-Fulcher-Tamman (VFT) models. The volume expansivities (β), molar volumes (Vm), molar refractions (Rm), and free volumes (fm) values have been calculated on the basis of density and refractive index data. The active energy of viscosity (Eη), molar electric conductivity (Λ), and ionicity were also determined. Partial structure-property relationship for DESs was also investigated. The tunable properties make DESs as a potential reaction medium, electrochemical process medium, solvent and absorbent. Therefore, the determination and correlation can provide relevant information for the engineering and industrial applications of DESs.

Thermogravimetric measurement of deep eutectic solvents vapor pressure

Knowledge of volatility of solvents in general and ionic liquids analogues in particular is crucial for thermodynamic modelling and proper solvent selection. In this study, the vapor pressure of a selected set of ionic liquids analogues known as deep eutectic solvents (DES) was investigated by thermogravimetric analysis (TGA). The experimental measurements were conducted for the practical temperature range of 343.15 to 393.15K. In general, measurements revealed that DESs have low but detectable vapor pressure. Compared to some common ionic liquids, DESs have higher vapor pressure. It is interesting to know that the vapor pressure-temperature relationship of DESs is more complex than that of molecular liquids as well as that of most ionic liquids. The conventional Antoine model was not able to explain the variation of vapor pressure with temperature. However, the vapor pressure was found to exhibit a noticeable trend with the DES critical temperature which was estimated theoretically. The Wagner vapor pressure model was able to predict the vapor pressure with an average %AAD of 2.89%.

Vibrational analysis and formation mechanism of typical deep eutectic solvents: An experimental and theoretical study

Deep eutectic solvents (DESs), as ionic liquid analogues for green solvents, have gained increasing attentions in chemistry. In this work, three typical kinds of DESs (ChCl/Gly, ChCl/AcOH and ChCl/Urea) were successfully synthesized and characterized by Fourier transform infrared spectroscopy (FTIR) and Raman. Then comprehensive and systematical analyses were performed by the methods of density functional theory (DFT). Two methods (B3LYP/6-311++G(2d,p) and dispersion-corrected B3LYP-D3/6-311++G(2d,p)) were employed to investigate the structures, vibrational frequencies and assign their ownership of vibrational modes for the DESs, respectively. Nearly all the experimental characteristic peaks of IR and Raman were identified according to the calculated results. By linear fitting of the combined calculated vs experimental vibration frequencies, it can be found that both of the two methods are excellent to reproduce the experimental results. Besides, hydrogen bonds were proved to exist in DESs by IR spectrum, structure analysis and RDG analysis. This work was aimed at predicting and understanding the vibrational spectra of the three typical DESs based on DFT methods. Moreover, by comparing experimental and theoretical results, it provides us a deep understanding of the formation mechanisms of DESs.

Novel amino acid‐based ionic liquid analogues: neutral hydroxylic and sulfur‐containing amino acids

AbstractDeep eutectic solvents (DESs) have shown potential promise for various industrial applications. Abundant research works were carried out on Type III DES employing choline chloride as the quaternary ammonium salt in combination with a variety of hydrogen bond donors (HBDs). Despite the fact that they are cheap, biodegradable, and have a wide application in food, polymer, and pharmaceutical industries, amino acids have not been utilized as HBD for the synthesis of DES. In this work, different ammonium‐based salts are used to synthesize different amino acid‐based DES systems. Four different amino acids are considered, two of which are neutral amino acids, namely L‐serine and L‐threonine, while the other two are based on the sulfur‐containing amino acids, namely L‐methionine and L‐cysteine. The successful DESs were characterized in terms of their physical properties. The melting point, density, viscosity, surface tension, refractive index, conductivity, and pH were measured for the successful DES systems at different temperatures ranging from 303.15 to 353.15 K. The introduction of such novel DES opens the door for performing more work on utilizing them for various chemical, biochemical, and pharmaceutical applications. © 2016 Curtin University of Technology and John Wiley & Sons, Ltd.

A Promising New Method to Estimate Drug-Polymer Solubility at Room Temperature

The established methods to predict drug-polymer solubility at room temperature either rely on extrapolation over a long temperature range or are limited by the availability of a liquid analogue of the polymer. To overcome these issues, this work investigated a new methodology where the drug-polymer solubility is estimated from the solubility of the drug in a solution of the polymer at room temperature using the shake-flask method. Thus, the new polymer in solution method does not rely on temperature extrapolations and only requires the polymer and a solvent, in which the polymer is soluble, that does not affect the molecular structure of the drug and polymer relative to that in the solid state. Consequently, as this method has the potential to provide fast and precise estimates of drug-polymer solubility at room temperature, we encourage the scientific community to further investigate this principle both fundamentally and practically.

Structural and Spectroscopic Characterizations of Amide-AlCl3-Based Ionic Liquid Analogues.

Several amide-AlCl3-based ionic liquid (IL) analogues were synthesized through a one-step method using three different structure amides as donor molecules. The effects of the steric and inductive effects of the methyl group substituted on the N atom on the asymmetric splitting of AlCl3 and the coordination site of the amide were investigated by (27)Al NMR, Raman, in situ IR, and UV-vis spectra for these IL analogues. Bidentate coordination through both the O and N atoms was dominant in the N-methylacetamide-AlCl3- and N,N-dimethylacetamide-AlCl3-based IL analogues because of the inductive effect of the methyl group. By contrast, the acetamide-AlCl3-based IL analogue presented mainly in the form of monodentate coordination via the O atom. Compared with monodentate coordination, bidentate coordination was favorable to the asymmetric splitting of AlCl3 with the same amide-AlCl3 molar ratio. Under the influence of the steric and inductive effects of the methyl group, the ionic species percentages in these IL analogues ranked in the following order: N-methylacetamide > N,N-dimethylacetamide > acetamide.

Effects of Supplemental Liquid DL-methionine Hydroxy Analog Free Acid in Diet on Growth Performance and Gastrointestinal Functions of Piglets.

This study was conducted to determine the effect of dietary supplementation of liquid DL-methionine hydroxy analog free acid (DL-MHA) on growth performance and gastrointestinal conditions of piglets. One hundred and eighty crossbred barrow piglets (Large White×Landrace, body weight: 12.48±0.33 kg) were divided into three groups with ten replications of six piglets each. Piglets received DL-MHA in diet at a concentration of 0 (control group), 0.15%, or 0.24%. The results indicated that increasing the standardized ileal digestible (SID) of sulfur amino acids (SAA) to lysine (SID SAA:Lys) ratio by supplementation of DL-MHA tended to increase (quadratic; p<0.10) weight gain and ADG, and showed slightly greater (linear; p<0.10) gain:feed ratio. The pH in the diet and cecum linearly decreased (p<0.01), whereas pH in colon had a quadratic response (p<0.01) with increasing supplementation of DL-MHA. By greater supplementation of DL-MHA, the population of Lactobacillus spp. in rectum was likely to increase (quadratic; p<0.10), but Escherichia coli population in the diet was reduced (quadratic; p<0.05). Acetic acid concentration and total short-chain fatty acids in cecum linearly increased (p<0.05), whereas valeric acid in cecum quadratically increased (p<0.05) with increasing DL-MHA levels. Moreover, the villous height of the jejunum quadratically increased (p<0.01) as the supplementation of DL-MHA was increased. It is concluded that the addition of DL-MHA in diet improved the growth performance and the morphology of gastrointestinal tract of piglets.

Novel amino acids based ionic liquids analogues: Acidic and basic amino acids

Deep eutectic solvents (DES) are one of the immerging promising industrial green solvents that are gaining considerable attention. These novel liquids have been synthesized from a variety of quaternary ammonium and phosphonium salts in combination with one or more complexing agents. Amino acids may act as good hydrogen bond donors and hence can be used as the complexing agent in the synthesis of type III DES. In this work a variety of ammonium quaternary salts have been investigated in forming amino acids-based DESs by combining with acidic or basic amino acids. Five of the common basic and acidic amino acids were used for this purpose. Three amino acids (glutamic acid, aspartic acid and arginine) were successful in forming DESs with the salt tetrabutylammonium chloride. The successful molar ratios of these DESs were characterized by measuring their melting point, density, viscosity, surface tension, refractive index, and conductivity in the temperature range 303.15–353.15 K. The presented novel data for these DESs can be utilized for customizing these solvents for probable chemical or industrial applications.

Citric acid-based deep eutectic solvents: Physical properties and their use as cosolvents in sulphuric acid-catalysed ethanolysis of oleic acid

Deep eutectic solvents (DESs) are noted to be green ionic liquid (IL) analogues, and their many favourable properties made them interesting for the scientific community. In this study, two novel DESs of citric acid with the monosaccharides D-glucose or D-fructose (1:1 molar ratio) were prepared and characterized. At the atmospheric pressure, the density, the dynamic viscosity, and the electrical conductivity of these eutectic solvents were measured and analysed as the function of temperature in the practical temperature range of 293.15-363.15 K. Arrhenius theory was employed for understanding the transport phenomena in these DESs. By using the experimental data, some important properties were calculated such as molecular volume, lattice energy, heat capacity, molar Gibbs energy, enthalpy and entropy of activation of viscous flow for the synthesized DESs. The fractional Walden rule was employed to establish the relationship between molar conductivity and viscosity, which proved an excellent linear behaviour. Finally, these DESs were tested as cosolvents in oleic acid (OA) ethanolysis. The investigated DESs possess many desirable properties, such as low vapour pressure, inflammability, biodegradability, and can be obtained from available renewable resources. These DESs showed to have the potential to be utilized for several industrial applications, like processing and separation of food constituents, pharmaceutical applications, and mediums for chemical reactions.

Mass connectivity index-based density prediction of deep eutectic solvents

Deep Eutectic Solvents (DES) are novel ionic liquid analogues that are gaining an increasing interest in the scientific community. Many novel applications have been reported for successfully using these solvents in diversity of fields. In this work, a new correlation is introduced for predicting their densities as a function of temperature. The concept of mass connectivity index (MCI) has been utilized for this purpose. The new correlation considers the molecular topology of the DES constituting molecules. The experimental density of a set comprising of 12 common DESs was used for optimizing the model. The new model was then validated using another set of 8 DESs. The new correlation attained an average relative deviation of around 0.07% for the two sets compared to that of more than 1% by the Rackett model. The MCI-based density model proved its superiority compared to the traditional Rackett density model as far as DESs are concerned.

Comparison of different indicators for the evaluation of feed mixing efficiency

The mixing process is essential for manufacturing animal feed, and due to the increased use of low-inclusion ingredients, its efficiency becomes even more important, as well as the methods to evaluate this efficiency. This study aimed to compare different internal and external indicators of feed mixing efficiency. Using an experimental horizontal paddle mixer, we evaluated dry mix cycle with dl-methionine 99%, L-lysine HCl 99%, l-threonine 98%, inorganic minerals (NaCl, CuCl2, MnSO4 and ZnSO4), vitamin B2 80%, and MicroTracer® (external indicator), and the wet mix cycle with dl-HMTBA (liquid analogue of methionine) 88% and liquid l-lysine 50%. The time required to achieve a homogeneous mix was also evaluated based on the coefficient of variation (CV) of such indicators every 15s between 20 and 155s of mixing. The mixing CV was below 5% for most of the tested indicators, except for vitamin B2 (21%) and CuCl2 (15%), whereas l-threonine showed the best mixing CV (3%). Powder and liquid sources of methionine and lysine had similar mixing efficiency at the end of the mixing cycles. The study indicated that the usage of powder and/or liquid industrial amino acids as internal indicators is suitable for evaluating the mixing efficiency as well as time required for achieving homogeneous mixes of feed mixers.

Influence of Polymer Molecular Weight on Drug–polymer Solubility: A Comparison between Experimentally Determined Solubility in PVP and Prediction Derived from Solubility in Monomer

In this study, the influence of polymer molecular weight on drug-polymer solubility was investigated using binary systems containing indomethacin (IMC) and polyvinylpyrrolidone (PVP) of different molecular weights. The experimental solubility in PVP, measured using a differential scanning calorimetry annealing method, was compared with the solubility calculated from the solubility of the drug in the liquid analogue N-vinylpyrrolidone (NVP). The experimental solubility of IMC in the low-molecular-weight PVP K12 was not significantly different from that in the higher molecular weight PVPs (K25, K30, and K90). The calculated solubilities derived from the solubility in NVP (0.31-0.32 g/g) were found to be lower than those experimentally determined in PVP (0.38-0.40 g/g). Nevertheless, the similarity between the values indicates that the analogue solubility can provide valuable indications on the solubility in the polymer. Hence, if a drug is soluble in an analogue of the polymer, it is most likely also soluble in the polymer. In conclusion, the solubility of a given drug-polymer system is determined by the strength of the drug-polymer interactions rather than the molecular weight of the polymer. Therefore, during the first screenings for drug solubility in polymers, only one representative molecular weight per polymer is needed.

Effects of concentration, salinity and injection scenario of ionic liquids analogue in heavy oil recovery enhancement

Abstract Recently, Deep Eutectic Solvents (DESs) have been demonstrated to be an effective analogue of ionic liquid in many applications. In our previous report, for the first time, two Chloride-based DESs were shown to have significant effects on different oil recovery mechanisms in heavy oil/formation brine/Berea sandstone system. In this report, the same DESs were used. The effects of DESs concentration, secondary and tertiary DES injections and brine salinity on recovery performance were examined through IFT measurements, contact angle measurements and core flooding experiments. Results of capillary number calculations indicated that although DESs solutions increased the IFT value, the capillary numbers in DESs flooding due to viscous forces and wettability alteration were higher than brine flooding case. Results showed that for both DESs, although the heavy oil recovery factors decreased by diluting the DES solution with brine from 50 vol% to 5 vol%, they were still promising between 6.3 and 8.7% for DES1 and DES2 respectively at lower concentrations of 5 vol%. Also, by reducing concentration from 50 to 25 vol%, there were no changes in recovery factors from 14 to 13.6% for DES1 and from 23.2 to 23.1% for DES2. The same trend was observed during wettability alteration study by contact angle measurements between oil droplet and aged surface of rock samples in the both DESs solutions at different concentrations. It verified that wettability alteration during DES injection has significant impact on oil recovery and it could be dominant and governing mechanism of heavy oil recovery enhancement. The DESs flooding in tertiary stage led to higher total recovery factors. The total recovery at tertiary mode compared to secondary mode were around 16% higher at 50 vol% concentrations and 3–6% higher at 5 vol% concentrations for both DESs. In addition, Results confirmed that the DESs can tolerate wide range of reservoir’s salinities and there were no big changes in oil recovery at different brine salinity during tertiary DESs injection.

Effects of DL-2-hydroxy-4-(methylthio) butanoic acid on broilers at different dietary inclusion rates

A growth experiment was conducted to determine the effectiveness of liquid analogue, DL-2-hydroxy-4-(methylthio) butanoic acid (HMTBA), compared to powder DL-methionine (DLM), in commercial maize–soybean-meal broiler diets similar to those commonly used in China, on feed conversion ratio (FCR), growth performance and European Production Index (EPI) of broilers.A 4 × 2 + 1 factorial arrangement of treatments was used in which HMTBA or DLM was fed at 4 concentrations (low, medium, high and very-high inclusion rates) of supplementation at 100% equivalence on an equimolar basis. Negative control diets were commercial starter, grower and finisher feeds with no added methionine. A total of 1008 commercial-type Arbor Acres 1-d-old chicks were randomly distributed into 9 groups, with 8 replicates of 14 (7 male + 7 female) birds per treatment.The body weight gain of the control group was significantly lower than that of the others in the starter period but did not show any differences during the other periods. The FCR of the control group was higher than that of the others except for those with HMTBA in the grower period. It was also observed that the FCR dropped as the supplemented concentration of methionine was increased regardless of the source. Some of the treatment groups produced a better breast yield than the control. The EPI between the two products did not show any significant difference.In conclusion, both of the methionine sources were equally effective in ameliorating the effects of a dietary deficiency of total sulphur amino acids.

ALIMET® (análogo líquido de metionina hidroxilada) en el sistema inmunitario, población de microflora y rendimiento de broilers

Este experimento se realizó para investigar el efecto de niveles crecientes de ALIMET ® (hidroxi análogo líquido de la metionina) en la dieta de broilers sobre los anticuerpos séricos, población microbiana y crecimiento. Se utilizó un diseño completamente al azar. Trescientos pollos Ross 308, no sexados fueron aleatoriamente asignados a 4 tratamientos con tres repeticiones de 25 pollos cada una. Los tratamientos incluían un control y tres niveles de suplementación de ALIMET ® (1,150, 1,437 y 1,725 g/kg en las dietas de iniciación y de 0,450; 0,562, y 0,675 g/kg en las dietas de crecimiento, respectivamente). Como resultado, la ganancia de peso aumentó linealmente con el incremento de la proporción de ALIMET ® en los periodos de 22 a 42 días (p

Triethylene glycol based deep eutectic solvents and their physical properties

Deep eutectic solvents (DESs) have been recently emerged as new ionic liquids (ILs) analogues. The low vapor pressure, inflammability, biodegradability and positive effect on the environment make DESs more favorable as neoteric solvents. In this study, triethylene glycol (TEG) was selected as a hydrogen bond donor (HBD) to form DESs with five types of phosphonium and ammonium salts, namely methyltriphenylphosphonium bromide (MTPB), benzyltriphenylphosphonium chloride (BTPC), allyltriphenylphosphonium bromide (ATPB), choline chloride (2-hydroxyethyl-trimethylammonium) (ChCl) and N,N-diethylenethanolammonium chloride (DAC). The physical properties of the synthesized DESs were measured such as freezing point, viscosity, electrical conductivity, Walden rule, density, pH and water content. In addition, the Fourier transform infrared spectroscopy (FTIR) was employed to study the functional groups. The experiments were conducted at different temperatures, i.e. 25–80 °C. It was found that DESs have suitable properties to be used in industrial processes such as separation, extraction, biochemical, petroleum and gas technology.

Effect of nano-particles on the rheological properties of Reline

The emerging utilization of ionic liquid analogues in different separation and chemical applications urges a thorough understanding of their rheological properties. In this study, the rheological properties of Reline as an example of deep eutectic solvents are considered under the effects of varying shear rate, temperature and the existence of solid nanoparticles. Three different common choline chloride:urea molar ratios are considered. In its pure state, Reline is a Newtonian fluid with common rheological properties at near room temperature conditions. The addition of nanoparticles (Aerosil and Laponite) considerably affects the rheological behavior of these fluids. It is interesting to report that the variations of the dispersion properties depend on the concentration of the nanoparticles. It is noticed that at low particle concentrations, the hydrogen bonding and possible electrostatic or van der Waals interactions are dominant, resulting in the increase of the dispersion viscosity. However, the opposite effect of particle–particle interaction becomes dominant at high concentrations and the viscosity of the solution reduces significantly. The effect due to the presence of nano-particles can be utilized to control the flow characteristics of these fluids.

A computational study of dicationic ionic liquids/CO₂ interfaces.

Recent studies on CO2 capture using dicationic ionic liquids (DILs) demonstrated that DILs are promising absorbents for CO2 uptake especially compared with monocationic ionic liquids (MILs) analogues, in which each cation carries single positive charge in contrast to two unit charges of a dication. However, DILs/CO2 interfacial properties at the molecular level are still unknown. This work investigated the CO2 absorption properties of representative DILs, 1-alkyl-3-dimethylimidazolium bis(trifluoromethylsulfonyl)imide, [Cn(mim)2](Tf2N)2 (n = 3, 6, 12), using molecular dynamics (MD) simulations. The higher interfacial CO2 density at DIL than that at MIL interfaces suggests the increased CO2 interaction sites in DILs. The interfacial CO2 density also exhibits an alkyl chain length dependence which decreases with the elongation of alkyl chain and proportionally correlates with the content of fluorine atoms at interfaces. Different alkyl chain orientations in DILs were illustrated in contrast to those of MILs; both DILs and CO2 inside DILs exhibit lower diffusivity than MILs, in agreement with the stronger cation-anion binding energy of DILs. Moreover, DILs show a lower H2O and N2 uptake from flue gas compared with MILs, implicating the higher CO2/H2O and CO2/N2 selectivity.

Separation of ethylbenzene and n-octane using deep eutectic solvents

AbstractIn this work, we have investigated the possibility of using low cost ionic liquid analogues, namely deep eutectic solvents (DESs), for the liquid-liquid extraction of ethylbenzene from

Study of electrode processes and deposition of cobalt thin films from ionic liquid analogues based on choline chloride

The cathodic processes of cobalt ion in ionic liquids consisting in binary mixtures of choline chloride (ChCl) with urea, ethylene glycol, malonic acid or oxalic acid were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The as-received hexahydrate cobalt chloride has been the precursor of cobalt ionic species. It was found that the reduction mechanism of Co2+ in ChCl-urea and ChCl-ethylene glycol is a quasi-reversible (or with high degree of irreversibility at high scan rate) and diffusion controlled process, whereas in ChCl-carboxilic acid solvents the cathodic process of Co2+ is overlapped with reduction of protons. By using Pt and vitreous carbon electrodes, one has computed the value for the Co2+ diffusion coefficient in ChCl-urea at 80 °C; in comparison with values obtained in aqueous solutions, this is up to two orders of magnitude lower. The paper also describes preliminary experiments concerning electrodeposition of cobalt thin films on copper substrate from the four ionic liquid analogue solvents containing choline chloride. The crystalline morphology and structural constitution of Co deposits were examined by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Good results regarding the quality and cobalt content in films were obtained for Co deposits using ChCl-urea or ChCl-ethylene glycol mixtures as solvents. The behaviour of Co films grown from these media was typical for a ferromagnetic material.