Water-rich Mixtures Research Articles

Solute–Solvent and Solvent–Solvent Interactions and Preferential Solvation of 1,1-Diamino-2,2-dinitroethylene in Aqueous Co-solvent Mixtures of N,N-Dimethylformamide and Dimethyl Sulfoxide

The effects of solvent properties on 1,1-diamino-2,2-dinitroethylene (FOX-7) solubility were investigated from the solubility values in aqueous co-solvent mixtures of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in terms of the linear solvation energy relationships with use of mathCAD software. For both aqueous mixtures, the main effect of hydrogen bond basicity was observed based on the solubility variation of FOX-7. The preferential solvation (the difference in composition between the solvation shell of the solute and the bulk composition in a mixture) of FOX-7 in the two aqueous of co-solvent solutions were investigated by using the method of inverse Kirkwood–Buff integrals (IKBI). The values of the preferential solvation parameters (δx1,3) were negative in water-rich mixtures, which are − 3.103×10−2 to − 2.936 × 10−2 for DMF (1) + water (2) mixtures and − 4.470 × 10−2 to − 3.995 × 10−2 for DMSO (1) + water (2) mixtures. However, in the co-solvent compositions ranging from 0.19 or 0.21 to 1 in mole fraction of DMF or DMSO, positive values of δx1,3 were observed. The preference of FOX-7 in water-rich mixtures can be explained based on the higher acidic behavior of FOX-7 molecules, which interact with the proton–acceptor functional groups of DMF and DMSO. KAT-LSER analysis showed that only the hydrogen-bond acceptor basicity of solvents played an important role on the FOX-7 solubility owing to its two amino functional groups. The squared correlation coefficient and F-statistic values are 0.98 and 314 for DMF + water mixture, and 0.96 and 130 for DMSO + water mixture, respectively.

Solubility of sulphadiazine in (acetonitrile + water) mixtures: measurement, correlation, thermodynamics and preferential solvation

ABSTRACTThe equilibrium solubility at temperatures from (293.15 to 313.15) K, dissolution thermodynamics and preferential solvation of sulphadiazine (SD) in {acetonitrile (ACN) (1) + water (2)} mixtures is reported. Mole fraction solubility of SD (x3) increases when temperature arises and also increases with the ACN proportion increasing. It varies from 4.81 × 10–6 in neat water to 6.02 × 10–4 in neat ACN at 298.15 K. Solubility behaviour was adequately correlated by Jouyban-Acree, modified Wilson and non-linear (proposed by Machatha et al.) models and the obtained mean percentage deviations (MPD) are 4.1%, 2.3% and 2.3%, respectively. The comparison of the MPD shows that the prediction using Jouyban-Acree model is more accurate than Jouyban-Acree-Abraham equation for solubility prediction of SD in {ACN (1) + water (2)}. From the variation of solubility with temperature the apparent thermodynamic analysis of dissolution was performed in all the mixtures and neat solvents. Based on the inverse Kirkwood-Buff integrals preferential solvation parameters were calculated. SD is preferentially solvated by water in water-rich mixtures (0.00 < x1 < 0.26) but preferentially solvated by ACN in the interval (0.26 < x1 < 0.65). In ACN-rich mixtures the behaviour is not well defined.

A novel approach to high temperature solar receivers with an absorbing gas as heat transfer fluid and reduced radiative losses

We report on a new high temperature solar receiver concept which exploits the ability of some molecular gases such as water vapor or carbon dioxide to absorb a significant fraction of longer wavelength thermal radiation while being mostly transparent to terrestrial solar radiation. The receiver operation principle is similar to the “greenhouse effect”: It relies on a gas volume between an aperture and a black surface heated by solar radiation to absorb the thermal re-radiation of the surface and shield the aperture from it. At the same time, the gas is heated by such absorption and acts as heat transfer fluid (HTF). The receiver works with radiation only as heat transfer mechanism and does not require, a priori, any convective contribution. To demonstrate the potential of the approach we modelled the system with the most accurate method available, spectral line-by-line (LBL) photon Monte Carlo raytracing with the absorption coefficients derived from the HITEMP 2010 spectroscopic database. We applied the model to a cylindrical cavity geometry with an axial gas flow. We simulated the performance for a large 16 m diameter, 16 m-long near-ambient pressure receiver with and without window at the 100 m2-aperture. The gases considered as HTF were steam, CO2, and mixtures of them. The gas outlet temperature was varied between 1000 K and 2000 K. We also simulated a small 1.6 m diameter, 1.6 m-long cylindrical cavity receiver with a 1 m2 windowed aperture and pressurized steam at 10 bar. With a solar irradiation flux of 1200 kW/m2 at the aperture, the receiver efficiency remained above 80% for gas outlet temperatures up to 1800 K for all receivers operated with steam. Carbon dioxide led to lower efficiencies, but water-rich mixtures of H2O and CO2 performed closely as good as pure steam. The proposed receiver concept represents a new opportunity towards low-cost high temperature solar technologies for processes beyond 1000 K.

Solubility of minoxidil in binary mixture of ethanol + water at various temperatures

ABSTRACTThe solubility of minoxidil in the aqueous binary mixtures of ethanol at different temperature are investigated and the obtained solubility data are fitted by using some cosolvency models including van’t Hoff equation, Yalkowsky model, Jouyban–Acree model and Jouyban–Acree–van’t Hoff model. The mean relative deviations (MRD%) are used to illustrate the models performance. Moreover, the apparent entropy, enthalpy, and Gibbs free energy of minoxidil dissolution process in the investigated solvent mixtures are computed using van’t Hoff and Gibbs equations. Finally, by means of the inverse Kirkwood–Buff integrals preferential solvation of minoxidil by water is observed in water-rich and ethanol-rich mixtures.

Novel computational tools based on bioinformatic and chemoinformatic data to complement zebrafish embryo teratogenicity test

The mole fraction solubility of buprofezin in aqueous co-solvent mixtures of N,N-dimethylformamide (DMF,1) + water (2), ethanol (1) + water (2), isopropanol (1) + water (2) and acetonitrile (1) + water (2) over the temperature range from (273.15 to 318.15) K was reported. At the same composition of DMF, ethanol, isopropanol or acetonitrile and temperature, the buprofezin solubility was highest in DMF (1) + water (2) mixtures. By using the Jouyban-Acree model, the buprofezin solubility was correlated obtaining RAD lower than 5.86% and RMSD lower than 15.60 × 10−4. Quantitative values for local mole fraction of DMF (ethanol, isopropanol or acetonitrile) and water nearby the buprofezin were calculated through the Inverse Kirkwood–Buff integrals method applied to the solubility. The values of preferential solvation parameters (δx1,3) were negative in water-rich mixtures but positive in co-solvent compositions from 0.19, 0.20 (0.25) or 0.25 to 1 in mole fraction of DMF, isopropanol, ethanol or acetonitrile, respectively. It was conjecturable that in water-rich mixtures, the hydrophobic hydration around the nonpolar methyl groups and aromatic ring group of buprofezin played a relevant important role in the solvation. The preference of buprofezin in water-rich mixtures could be explained in terms of the higher basic behaviour of buprofezin molecules interacting with the proton-donor functional groups of the water. In addition, solute-solvent and solvent-solvent interactions of buprofezin in the DMF (ethanol, isopropanol or acetonitrile) + water mixtures were investigated from the solubility data by using the linear solvation energy relationships concept. The variation of buprofezin solubility depended mainly upon the hydrogen bond acidity and cavity term for ethanol (isopropanol) + water mixtures, and the cavity term for DMF (acetonitrile) + water mixtures.

The origin of the conductivity maximum vs. mixing ratio in pyridine/acetic acid and water/acetic acid

Explanations are provided for the first time for the historically known locations of electrical conductivity maxima versus mixing ratio (mole fraction of acid, xA) in mixtures of (i) acetic acid with water and (ii) acetic acid with pyridine. To resolve the question for the second system, density-functional-based molecular dynamic simulations were performed, at 1:1, 1:2, 1:3, 1:5, and 1:15 mixing ratios, to gain vital information about speciation. In a zeroth-order picture, the degree of ionization (and hence conductivity) would be maximal at xA = 0.5, but these two examples see this maximum shifted to the left (water/acetic acid, xAmax = 0.06), due to improved ion stability when the effective dielectric constant is high (i.e., water-rich mixtures), or right (pyridine/acetic acid xAmax = 0.83), due to improved acetate stability via "self-solvation" with acetic acid molecules (i.e., acid-rich mixtures) when the dielectric constant is low. A two-parameter equation, with theoretical justification, is shown to reproduce the entire 0 < xA < 1 range of data for electrical conductivity for both systems. Future work will pursue the applicability of these equations to other amine/carboxylic acid mixtures; preliminary fits to a third system (trimethylamine/acetic acid) give curious parameter values.

Solubility and thermodynamics of lamotrigine in carbitol + water mixtures from T = (293.2 to 313.2) K

The solubility of lamotrigine (LTG) are measured in aqueous mixtures of carbitol at temperatures ranging from 293.2 to 313.2 K. LTG solubility increases with increasing mass fraction of carbitol, and maximum solubility is observed in neat carbitol. Four cosolvency mathematical models; i.e., Yalkowsky model, Jouyban–Acree model, Jouyban–Acree–van’t Hoff model and modified Wilson model are fitted to the experimental results, and back-calculation is performed by using the solubility data in monosolvents in which the mean relative deviation of the investigated models are 64.8%, 9.0%, 7.2%, and 46.7%, respectively. Furthermore, the apparent thermodynamic properties of the dissolution process are computed according to van’t Hoff and Gibbs equations. The preferential solvation is analyzed based on the inverse Kirkwood-Buff integrals by using the solubility values at 298.2 K. LTG is preferentially solvated by water in water-rich mixtures (0.00 < x1 < 0.12) and by carbitol in mixtures with solvent composition of 0.12 < x1 < 1.00.

Solution Thermodynamics and Preferential Solvation of Atenolol in {Ethanol (1) + Water (2)} Cosolvent Mixtures

The solubility of atenolol (ATN) in some {ethanol (1) + water (2)} mixtures expressed in mole fraction at temperatures from 298.2 to 313.2 K was calculated from reported solubility values expressed in molarity scale. The van’t Hoff and Gibbs equations were used to calculate the respective apparent thermodynamic functions: Gibbs energy, enthalpy, and entropy of the dissolution processes. Non-linear enthalpy–entropy relationship was observed for this drug ATN in the plot of enthalpy vs. Gibbs energy of solution with negative slope in the composition region 0.00 £ w1 £ 0.20 but positive slope in the region 0.20 £ w1 £ 0.40. Beyond this composition, the behavior is more complex. Hence, the driving mechanism for ATN dissolution process is the entropy in water-rich mixtures and the enthalpy in mixtures 0.20 £ w1 £ 0.40. Furthermore, the preferential solvation of ATN by both solvents was analyzed by using the inverse Kirkwood-Buff integrals observing that this drug is preferentially solvated by water molecules in water-rich and also in ethanol-rich mixtures but preferentially solvated by ethanol molecules in mixtures 0.24 £ x1 £ 0.51.

Solute-solvent and solvent-solvent interactions and preferential solvation of limonin in aqueous co-solvent mixtures of methanol and acetone

Solute-solvent and solvent-solvent interactions of limonin in binary solvent mixtures of methanol + water and acetone + water were investigated from the solubility data by using the linear solvation energy relationships concept. The variation of limonin solubility depended mainly upon the hydrogen bond basicity for methanol (1) + water (2) mixtures, and the cavity term for acetone (1) + water (2) mixtures. The preferential solvation parameters (δx1,3) of limonin in two solvent mixtures were derived by means of the inverse Kirkwood–Buff integrals method. δx1,3 values were negative in water-rich mixtures but positive in solvent compositions from 0.24 or 0.20 (0.25) to 1 in mole fraction of methanol or acetone, respectively. It was conjecturable that in water-rich mixtures, the hydrophobic hydration around the nonpolar methyl groups of limonin played a relevant role in the solvation. The preference of limonin in water-rich mixtures could be explained in terms of the higher basic behavior of limonin molecules interacting with the proton-donor functional groups of the water.

Preferential solvation of tricin in {ethanol (1) + water (2)} mixtures at several temperatures

Los parámetros de solvatación preferencial del tricina en mezclas {etanol (1) + agua (2)} se obtuvieron a partir de las propiedades termodinámicas de solución, medianteel método de las integrales inversas de Kirkwood-Buff. La tricina es muy sensible a los efectos de solvatación específicos, por lo que el parámetro de solvatación preferencial, δx1,3, es negativo en las mezclas ricas en agua, pero positivo en todas las otras composiciones a temperaturas desde 293,15 hasta 313,15 K. Se puede establecer que en mezclas ricas en agua la hidratación hidrofóbica alrededor de los grupos aromáticosy metilo del fármaco tiene un papel relevante en la solvatación. La mayor solvatacióndel fármaco por etanol se presenta en mezclas de proporción intermedia y en mezclas ricas en etanol, esto podría deberse principalmente a los efectos de la polaridad.En estas mezclas, el fármaco actuaría como ácido de Lewis con las moléculas de etanol, puesto que este codisolvente es más básico que el agua.

Solubility of bosentan in {propylene glycol + water} mixtures at various temperatures: experimental data and mathematical modelling

ABSTRACTSolubility measurements were performed for bosentan (BST) in binary mixtures of propylene glycol (PG) and water at atmospheric pressure within the temperature range, T = 293.2 – 313.2 K by employing a shake-flask method. Generated solubility data were correlated with Jouyban-Acree-van’t Hoff model and the accuracies of the predicted solubilities and model performance were illustrated by mean relative deviations (MRD). Furthermore, the apparent thermodynamic properties of BST dissolving in all the mixed solvents were calculated, and the obtained results show that the dissolution process is endothermic. By using the inverse Kirkwood–Buff integrals, it was observed that BST is preferentially solvated by water in water-rich solvent mixtures and preferentially solvated by PG (as a cosolvent) in the composition range of 0.20 < x1 < 1.00 at 298.2 K.

Equilibrium solubility and preferential solvation of 1,1′-sulfonylbis(4-aminobenzene) in binary aqueous solutions of n -propanol, isopropanol and 1,4-dioxane

Abstract The equilibrium solubility of 1,1′-sulfonylbis(4-aminobenzene) (dapsone) in neat solvents of n-propanol, isopropanol 1,4-dioxane and water and in cosolvent mixtures of n-propanol + water, isopropanol + water and 1,4-dioxane + water were determined experimentally by the saturation shake-flask method within the temperature range from 278.15 K to 323.15 K under atmospheric pressure of 101.0 kPa. The mole fraction solubility of dapsone increased with increasing temperature and mass fraction of cosolvent in each binary system. At the same temperature and mass fraction of the organic solvent, the solubility of dapsone was greater in (1,4-dioxane + water) than in the other two cosolvent mixtures. The type and extent of solvent effect was analyzed by KAT-LSER approach. The obtained solubility was mathematically represented by using the Jouyban-Acree model, van’t Hoff-Jouyban-Acree model and Apelblat-Jouyban-Acree model obtaining average relative deviations lower than 4.88% and root-mean-square deviation lower than 5.86 × 10−4 for correlative studies. Positive values of the apparent dissolution enthalpy illustrated that the dissolution process of dapsone in these mixed solvents was endothermic. Furthermore, the preferential solvation parameters were derived from their thermodynamic solution properties by means of the inverse Kirkwood–Buff integrals. The preferential solvation parameters for n-propanol, isopropanol or 1,4-dioxane (δx1,3) were negative in water-rich mixtures but positive in compositions from 0.24 (0.19, 0.18) in mole fraction of n-propanol (isopropanol or 1,4-dioxane) to neat n-propanol (isopropanol or 1,4-dioxane). It was conjecturable that in former case the hydrophobic hydration around phenyl groups could play a more relevant role than hydrophilic hydration.

Cosolvent effect on the dynamics of water in aqueous binary mixtures

ABSTRACTWater rotational dynamics in the mixtures of water and amphiphilic molecules, such as acetone and dimethyl sulfoxide (DMSO), measured by femtosecond infrared, often vary non-monotonically as the amphiphilic molecule's molar fraction changes from 0 to 1. Recent study has attributed the non-ideal water rotation with concentration in DMSO–water mixtures to different microscopic hydrophilic–hydrophobic segregation structure in water-rich and water-poor mixtures. Interestingly, the acetone molecule has very similar molecular structure to DMSO, but the extremum of the water rotational time in the DMSO-water mixtures significantly shifts to lower concentration and the rotation of water is much faster than those in acetone-water mixtures. The simulation results here shows that the non-ideal rotational dynamics of water in both mixtures are due to the frame rotation during the interval of hydrogen bond (HB) switchings. A turnover of the frame rotation with concentration takes place as the structure transition of mixture from the hydrogen bond percolation structure to the hydrophobic percolation structure. The weak acetone–water hydrogen bond strengthens the hydrophobic aggregation and accelerates the relaxation of the hydrogen bond, so that the structure transition takes places at lower concentration and the rotation of water is faster in acetone–water mixture than in DMSO–water mixture. A generally microscopic picture on the mixing effect on the water dynamics in binary aqueous mixtures is presented here.

Solvent effect on a model SNAr reaction in ionic liquid/water mixtures at different compositions

A biphasic behavior observed on the reaction rate of a model SNAr reaction in ionic liquid/water mixtures was explained by preferential solvation effects in water rich mixtures, and an anion effect in mixtures with high ionic liquid content.

Solubility of Genistin in Ethanol/Acetone + Water and Daidzein in Ethanol + Water Co-solvent Mixtures Revisited: IBKI Preferential Solvation Method

The preferential solvation parameters (δx1,3) of genistin in ethanol/acetone (1) + water (2) and daidzein in ethanol (1) + water (2) co-solvent mixtures at elevated temperatures were derived from available solubility data using the inverse Kirkwood–Buff integral method. The values of δx1,3 varied non-linearly with the co-solvent (1) proportion in all the aqueous mixtures. For the three co-solvent mixtures, the values of δx1,3 were negative in water-rich mixtures, which indicated that daidzein or genistin was preferentially solvated by water and can act as Lewis bases to establish hydrogen bonds with the proton-donor functional groups of water (1). The same behavior was also observed for daidzein in ethanol (1) + water (2) and acetone (1) + water (2) mixtures with co-solvent-rich composition. For daidzein in ethanol (1) + water (2) mixtures with composition 0.24 < x1 < 1, and genistin in ethanol (1) + water (2) and acetone (1) + water (2) mixtures with intermediate compositions, the local mole fractions of ethanol or acetone were higher than those of the mixtures and therefore the δx1,3 values were positive, which indicated that genistin and daidzein were preferentially solvated by the co-solvent. In these regions, daidzein and genistin were acting as a Lewis acid with ethanol or acetone molecules.

Modelling the Preferential Solvation of Ferulic Acid in {2-Propanol (1) + Water (2)} Mixtures at 298.15 K

Background: Recently Haq et al. reported the equilibrium solubility in {2-propanol (1) + water (2)} mixtures at several temperatures with some numerical correlation analysis. Nevertheless, no attempt was made to evaluate the preferential solvation of this compound by the solvents. Methods: Preferential solvation of ferulic acid in the saturated mixtures at 298.15 K was analyzed based on the inverse Kirkwood-Buff integrals as described in the literature. Results: Ferulic acid is preferentially solvated by water in water-rich mixtures (0.00 < x1 < 0.19) but preferentially solvated by 2-propanol in mixtures with composition 0.19 < x1 < 1.00. Conclusion: These results could be interpreted as a consequence of hydrophobic hydration around the non-polar groups of the solute in the former case (0.00 < x1 < 0.19). Moreover, in the last case (0.19 < x1 < 1.00), the observed trend could be a consequence of the acid behavior of ferulic acid in front to 2-propanol molecules because this cosolvent is more basic than water as described by the respective solvatochromic parameters.

Solution thermodynamics and preferential solvation of triclocarban in {1,4-dioxane (1) + water (2)} mixtures at 298.15 K

ABSTRACTThe equilibrium solubility and preferential solvation of triclocarban in {1,4-dioxane (1) + water (2)} mixtures at 298.15 K was reported. Mole fraction solubility varies continuously from 2.85 × 10–9 in neat water to 2.39 × 10–3 in neat 1,4-dioxane. Solubility behaviour was adequately correlated by means of the Jouyban-Acree model. Based on the inverse Kirkwood-Buff integrals, preferential solvation parameters were calculated. Triclocarban is preferentially solvated by water in water-rich mixtures (0.00 < x1 < 0.18) and also in 1,4-dioxane-rich mixtures (0.78 < x1 < 1.00) but preferentially solvated by 1,4-dioxane in mixtures with similar solvent compositions.

Characterization of thin film CO2 ice through the infrared ν1 + ν3 combination mode

Carbon dioxide is abundant in ice mantles of dust grains; some is found in the pure crystalline form as inferred from the double peak splitting of the bending profile at about 650 cm$^{-1}$. To study how CO$_2$ segregates into the pure form from water-rich mixtures of ice mantles and how it then crystallizes, we used Reflection Absorption InfraRed Spectroscopy (RAIRS) to study the structural change of pure CO$_2$ ice as a function of both ice thickness and temperature. We found that the $\nu_1+\nu_3$ combination mode absorption profile at 3708~cm$^{-1}$ provides an excellent probe to quantify the degree of crystallinity in CO$_2$ ice. We also found that between 20 and 30~K, there is an ordering transition that we attribute to reorientation of CO$_2$ molecules, while the diffusion of CO$_2$ becomes significant at much higher temperatures. In the formation of pure crystalline CO$_2$ in ISM ices, the rate limiting process is the diffusion/segregation of CO$_2$ molecules in the ice instead of the phase transition from amorphous to crystalline after clusters/islands of CO$_2$ are formed.

Preferential solvation of some antiepileptic drugs in {cosolvent (1) + water (2)} mixtures at 298.15 K

ABSTRACTThe solubility of lamotrigine (LTG), clonazepam (CZP) and diazepam (DZP) in some {cosolvent (1) + water (2)} mixtures expressed in mole fraction at 298.15 K was calculated from reported solubility values expressed in molarity by using the densities of the saturated solutions. Aqueous binary mixtures of ethanol, propylene glycol and N-methyl-2-pyrrolidone were considered. From mole fraction solubilities and some thermodynamic properties of the solvent mixtures, the preferential solvation of these drugs by both solvents in the mixtures was analysed by using the inverse Kirkwood–Buff integrals. It is observed that LTG, CZP and DZP are preferentially solvated by water in water-rich mixtures in all the three binary systems analysed. In {ethanol (1) + water (2)} mixtures, preferential solvation by water is also observed in ethanol-rich mixtures. Nevertheless, in {propylene glycol (1) + water (2)} and {N-methyl-2-pyrrolidone (1) + water (2)} mixtures preferential solvation by the cosolvent was observed in cosolvent-rich mixtures.

Ethanol Solvation in Water Studied on a Molecular Scale by Photoelectron Spectroscopy.

Because of the amphiphilic properties of alcohols, hydrophobic hydration is important in the alcohol-water system. In the present paper we employ X-ray photoelectron spectroscopy (XPS) to investigate the bulk and surface molecular structure of ethanol-water mixtures from 0.2 to 95 mol %. The observed XPS binding energy splitting between the methyl C 1s and hydroxymethyl C 1s groups (BES_[CH3-CH2OH]) as a function of the ethanol molar percentage can be divided into different regions: one below 35 mol % with higher values (about 1.53 eV) and one starting at 60 mol % up to 95 mol % with 1.49 eV as an average value. The chemical shifts agree with previous quantum mechanics/molecular mechanics (QM/MM) calculations [ Löytynoja , T. ; J. Phys. Chem. B 2014 , 118 , 13217 ]. According to these calculations, the BES_[CH3-CH2OH] is related to the number of hydrogen bonds between the ethanol and the surrounding molecules. As the ethanol concentration increases, the average number of hydrogen bonds decreases from 2.5 for water-rich mixtures to 2 for pure ethanol. We give an interpretation for this behavior based on how the hydrogen bonds are distributed according to the mixing ratio. Since our experimental data are surface sensitive, we propose that this effect may also be manifested at the interface. From the ratio between the XPS C 1s core lines intensities we infer that below 20 mol % the ethanol molecules have their hydroxyl groups more hydrated and possibly facing the solution's bulk. Between 0.1 and 14 mol %, we show the formation of an ethanol monolayer at approximately 2 mol %. Several parameters are derived for the surface region at monolayer coverage.