Aqueous Mixtures Of Ethylene Glycol Research Articles

Prediction of drug solubility in ethylene glycol + water mixtures using generally trained cosolvency models

This work reports the results obtained from the generally trained versions of Yalkowsky and Jouyban-Acree models for prediction of drugs' solubility in binary mixtures of ethylene glycol + water at different temperatures. To achieve a full predictive model, the Abraham solvation solute parameters are combined with the Jouyban-Acree and Jouyban-Acree-van't Hoff models. In this respect, the solubility data sets of 14 drugs with various polarities and structural features in aqueous ethylene glycol mixtures are collected from literature and correlated with the above-mentioned models, the overall mean relative deviation values for the back-calculated drug's solubility indicating the generally trained models have an acceptable performance in solubility prediction and can be useful in pharmaceutical industry.

Dynamics of liquid imbibition through partially soluble porous sheets

We investigate the dynamics of liquid imbibition through partially soluble porous sheets. Using a polymeric porous sheet composed of polyethylene oxide (PEO) nanofibers, we examine the imbibition of mixtures of ethylene glycol (EG) that does not dissolve PEO and water that dissolves PEO. For aqueous EG mixtures with a concentration of greater than 70 wt% that only partially dissolves a PEO nanofibrous sheet, imbibition with dissolution is markedly slower than without dissolution. By developing a mathematical model to predict the imbibition velocity, we elucidate how dissolution changes the viscosity of the invading liquid and affects the dynamics of imbibition. This study guides us to extend the classical theoretical framework for liquid imbibition through porous media to complex porous media involving dissolution. Thus, a useful background is provided for long-term drug delivery using partially soluble porous materials and for engineering processes, such as geological sequestration and exploration, and coffee percolation.

Aggregation and adsorption properties of benzyldimethylhexadecylammonium tetrachloromanganate(II) metallosurfactant in water–ethylene glycol medium

The aggregation and adsorption properties of metallosurfactant, benzyldimethylhexadecylammonium tetrachloromanganate(II) (BDHA2[MnCl4], where BDHA represents benzyldimethylhexadecylammonium group) in binary aqueous mixtures of ethylene glycol (EG) were investigated by tensiometric, conductometric, dynamic light scattering (DLS) and transmission electron microscopy (TEM) methods at 298.15 K. The percentage of EG (by weight) was varied between 0 and 100%. The physicochemical properties determined and discussed include critical micelle concentration (cmc), counterion binding constant (β), Gibbs free energy of micellization (), surface excess at cmc (), minimum area per surfactant molecule (), surface pressure (πcmc), minimum free energies (G min) and size of aggregates. This study revealed that with increase in percentage of EG the cmc of BDHA2[MnCl4] metallosurfactant increases and the cmc of BDHA2[MnCl4] in EG is about 158 times higher than that in water. The counterion binding constant values increase with increase in percentage of EG from 10% to 70% and thereafter decrease. The adsorption of metallosurfactant at the air–solution interface decreases as the EG content in the bulk increases. The values were found to be negative and the negative value decreases with increase in percentage of EG. Gordon parameter and ratio of surface tension of medium to that of the metallosurfactant solution at cmc are used to represent solvophobicity of the medium. DLS measurements revealed that the hydrodynamic diameters (d H) of the micelles increase with increase in percentage of EG (in pure EG, d H = 28.3 nm). TEM measurements showed the presence of spherical micelles.

Activation Energy Parameters for Hydrodynamic Permeability of Divalent Transition Metal Sulphates and Magnesium Sulphate in Binary Aqueous Mixtures of Ethylene Glycol

Activation Energy Parameters for Hydrodynamic Permeability of Divalent Transition Metal Sulphates and Magnesium Sulphate in Binary Aqueous Mixtures of Ethylene Glycol

Prediction of deferiprone solubility in aqueous mixtures of ethylene glycol, propylene glycol and polyethylene glycol 400 at various temperatures

Solubility of drugs is essential information and no data is available for deferiprone (DFP) in the literature. The solubility of DFP in water, ethylene glycol (EG), propylene glycol (PG) and polyethylene glycol 400 (PEG 400) at 293.2, 298.2, 303.2, 308.2 and 313.2K is reported and mathematically represented by van't Hoff equation. The solubility of DFP in aqueous binary mixtures of EG, PG and PEG 400 at 298.2K is determined using the shake flask method and the generated data is used to train the Jouyban–Acree model. The trained versions of the van't Hoff and Jouyban–Acree models are combined to provide predictive models for solubility of DFP in the investigated solvent systems. The mean percentage deviations of the back-calculated solubilities against the corresponding experimental values were 1.3 and 1.1%, respectively for the mono- and mixed solvent systems.

Thermal Properties and Mixing State of Diol−Water Mixtures Studied by Calorimetry, Large-Angle X-Ray Scattering, and NMR Relaxation

Differential scanning calorimetry (DSC) has been performed on aqueous mixtures of three diols, which involve a linear carbon chain, HO-(CH 2) n -OH ( n = 3, 4, and 5), over the whole mole fraction range of diols. The DSC results have shown the alkyl chain parity for the freezing process of the aqueous mixtures: aqueous mixtures of 1,3-propanediol (PrD) and 1,5-pentanediol (PeD) are kept in the supercooled state or vitrified over a wide mole fraction range, while those of 1,4-butanediol (BuD) are easily crystallized. The structure of PrD-water mixtures has been elucidated by using the large-angle X-ray scattering (LAXS) technique. It has been suggested that the structural change of PrD-water mixtures occurs at PrD mole fractions of x PrD = 0.4 and 0.8: in the range of x PrD < or = 0.4 where the tetrahedral-like structure of water predominates, in the range of 0.4 < x PrD < 0.8 where both PrD and water structures coexist, and in the range of x PrD > or = 0.8 where the inherent structure of PrD is mainly formed. (17)O and (1)H NMR relaxation measurements have been made on aqueous mixtures of ethylene glycol (EG, n = 2), PrD, and BuD to clarify the dynamics of H 2 (17)O and diol molecules. The (17)O NMR relaxation rates have suggested that the rotational motion of water molecules is gradually retarded in the diol-water mixtures with increasing diol content and that the restriction of the motion is more remarkable in the order of EG < PrD < BuD. On the basis of all the results, together with comparison with those of methanol-water, ethanol-water, and 1-propanol-water mixtures previously reported, the mixing state of diol-water mixtures has been discussed at the molecular level.

Conformation–activity relationship of peptide T and new pseudocyclic hexapeptide analogs

Peptide T (ASTTTNYT), a segment corresponding to residues 185-192 of gp120, the coat protein of HIV, has several important biological properties in vitro that have stimulated the search for simpler and possibly more active analogs. We have previously shown that pseudocyclic hexapeptide analogs containing the central residues of peptide T retain considerable chemotactic activity. We have now extended the design of this type of analogs to peptides containing different aromatic residues and/or Ser in lieu of Thr. The complex conformation-activity relationship of these analogs called for a reexamination of the basic conformational tendencies of peptide T itself. Here, we present an exhaustive NMR conformational study of peptide T in different media. Peptide T assumes a gamma-turn in aqueous mixtures of ethylene glycol, a type-IV beta-turn conformation in aqueous mixtures of DMF, and a type-II beta-turn conformation in aqueous mixtures of DMSO. The preferred conformations for the analogs were derived from modeling, starting from the preferred conformations of peptide T. The best models derived from the gamma-turn conformation of peptide T are those of peptides XII (DSNYSR), XIII (ETNYTK) and XVI (ESNYSR). The best models derived from the type-IV beta-turn conformation of peptide T are those of peptides XIV (KTTNYE) and XV (DSSNYR). No low-energy models could be derived starting from the type-II beta-turn conformation of peptide T. The analogs with the most favored conformations are also the most active in the chemotactic test.

Effect of temperature on the partial molar volumes of some divalent transition metal sulphates and magnesium sulphate in the water-rich region of aqueous mixtures of ethylene glycol

Partial molar volumes of some divalent transition metal sulphates, viz. manganese sulphate, cobalt sulphate, nickel sulphate, copper sulphate, zinc sulphate and magnesium sulphate, have been determined (in the concentration range 0.005–0.100 mol kg − 1 ) in water and aqueous mixtures of ethylene glycol (EG) (5%, 10%, 15%, 20% and 25% by weight of EG) from solution density measurements at 303.15 K, in water and in 5% (w/w) EG + water at five different temperatures. The data have been analysed using the Masson equation and the obtained parameters interpreted in terms of ion–ion and ion–solvent interactions. The partial molar volumes vary with temperature as a power series of temperature. Structure making/breaking characters of the electrolytes have been inferred from the sign of [∂ 2 ϕ v 0/∂ T 2] p, i.e. second derivative of partial molar volume with respect to temperature at constant pressure. All the electrolytes have been found to act as structure makers/promoters in water as well as in aqueous mixtures of ethylene glycol.

Volumetric behavior of a bolaamphiphile in different amides–water and ethylene glycol–water mixtures

The effect of binary aqueous mixtures of ethylene glycol (EG), formamide (FA), N-methylformamide (NMF), dimethylformamide (DMF), and their pure phase on the apparent molar volume ϕ V of the bolaamphiphile decamethonium bromide (C 10Me 6) has been investigated at 298.15 K. The behavior of standard molar volumes V 2 0 and transfer volumes Δ t ϕ V of C 10Me 6 from water to solvent/water (S/W) binary mixtures, shows different minima and maxima depending on the composition of the solvent. This behavior is influenced by the nature of the cosolvent and on the type of the solute and more or less corresponds to volumetric changes in the S/W mixture. The investigation of the transfer volumes in different fixed concentrations reveals an inversion of Δ t ϕ V values between the compositions, which suggests a differentiation of the effects of different volume contributions on the partial molar volume of ions. The correlation of Δ t ϕ V with the dielectric constant of the aqueous amide mixtures shows that the behavior of Δ t ϕ V vs x amide reflects the changes of ɛ E vs x amide .

Preferential solvation in mixed solvents. 12. Aqueous glycols

The Kirkwood-Buff integrals of aqueous mixtures of ethylene glycol, 1,2-propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and the polyethyleneglycols PEG300 and PEG400 were calculated from thermodynamic data. Volume-corrected preferential solvation parameters for the first solvation shell were then calculated with correlation volumes pertaining to linear oligomeric molecules rather than spherical ones, provided the preferential solvation is small, as is the case for the glycols. The numbers of water molecules associated with each oxygen atom of the glycols in dilute solutions were obtained from these data.

Effect of ethylene glycol on the thermodynamic and micellar properties of Tween 20

The aggregation behaviour of Tween 20 in ethylene glycol–water mixed solvents has been investigated using surface tension, density, static and dynamic light scattering, and fluorescence measurements. Micellar and surface thermodynamics data were obtained from the temperature dependence of critical micelle concentrations in various aqueous mixtures of ethylene glycol. In order to evaluate the influence of the cosolvent, the differences in the Gibbs energies of micellization of Tween 20 between water and binary solvents were determined. This study allowed us to conclude that the ability of ethylene glycol to act as a structure breaker and its interaction with the surfactant hydrophilic group are the controlling factors of the micellization process. From the evaluation of the thermodynamics of adsorption at the solution–air interface, it was determined that the surface activity of the surfactant decreases slightly with increasing concentration of ethylene glycol at a given temperature. Partial specific volume data, obtained by density measurements, indicate that the fraction of solvent molecules interacting with the micelle, via hydrogen bonds, remained roughly constant. The effect of cosolvent on the size and solvation of the aggregates was analysed by means of static and dynamic light scattering measurements. It was found that the aggregation number decreased, whereas the whole micellar solvation increased with the ethylene glycol content. Micellar micropolarity was examined using two different probes, pyrene and 8-anilinonaphthelene-1-sulfonic acid, and was found to increase with ethylene glycol addition, accompanied by an enhanced solvation. Fluorescence polarization measurements found by using coumarin 6 as a hydrophobic probe revealed an increase in the micellar microviscosity. The observed trends in these microenvironmental properties were ascribed to a participation by ethylene glycol in the micellar solvation layer.

Thermodynamic and Structural Studies of Triton X-100 Micelles in Ethylene Glycol−Water Mixed Solvents

Micellar properties of p-tert-octyl-phenoxy (9.5) polyethylene ether (Triton X-100) in aqueous mixtures of ethylene glycol (EG) were determined using such techniques as surface tension, static and dynamic light scattering, and fluorescence spectroscopy. Thermodynamics of micellization was obtained from the temperature dependence of critical micelle concentration values. The differences in the Gibbs energies of micellization of Triton X-100 between water and binary solvent systems were calculated to evaluate the influence of cosolvent on the micellization process. From this study, it can be concluded that the structure-breaking ability of EG and its interaction with the oxyethylene groups of the surfactant are dominating factors in the micellization process. Thermodynamics of adsorption of the solution−air interface was also evaluated. It was found that the surface activity of the surfactant decreases slightly with increasing concentration of EG at a given temperature. By a combination of static and dynamic light scattering measurements, a reduction of the micelle size was observed, mainly due to a decrease of the micellar aggregation number, whereas the micellar solvation was not substantially modified in magnitude with EG addition. However, the change of the surface area per headgroup of the surfactant suggested an alteration in the nature of its solvation layer, produced probably by a certain participation of cosolvent in the micellar solvation layer. This point was corroborated from the fluorescence polarization studies of several luminescent probes, including coumarin 6, merocyanine 540, and rhodamine B. These experiments revealed a slight increase of the micellar microviscosity. Finally, the proposed mechanism was also supported by the increase observed in the cloud point of Triton X-100, induced by the EG addition.

Thermodynamic properties of micellization of sodium dodecyl sulfate in binary mixtures of ethylene glycol with water

Micellar properties of sodium dodecyl sulfate (SDS) in aqueous mixtures of ethylene glycol (EG) were determined using techniques such as conductivity, density, EMF, surface tension, viscosity, ultrasonic velocity, and spectroscopy (fluorescence). The effective degree of disssociation of micelles (α) was determined using three different methods. Thermodynamics of micellization were obtained from the temperature dependence of critical micelle concentrations (cmc) values. The difference in Gibbs energies of micellization [Formula: see text] of SDS, between water and mixed solvent systems, was calculated to evaluate the influence of cosolvent on the micellization process. Surfactant aggregation numbers (Ns) obtained from static fluorescence quenching methods indicated a decrease in the aggregation numbers with increasing concentration of ethylene glycol in the binary solvent mixtures. In addition, the micropolarity of the micellar interior was determined from the pyreneI1/I3 ratios. These values were consistent with a decrease in the micropolarity surrounding the probe molecule as the EG content in the solvent mixture was increased. Key words: thermodynamics, micellization, aggregation numbers, ultrasonic velocity, degree of dissociation.

Matrix macromolecules that affect the viscoelasticity of calfskin.

The chemical basis of viscoelasticity of bovine skin was explored by mechanical relaxation spectroscopy after selective enzymatic degradation. Measurements covered a wide range of time scales because water was replaced in the tissue with aqueous mixtures of ethylene glycol, which maintained a water-like electrical environment for the charged macromolecules down to -50 degrees C. Macromolecular components that couple the fibrils to the interfibrillar matrix contribute about half the values of the resultant storage and loss moduli, while removal of components that are readily extractable, so perhaps free in the matrix, did not alter these mechanical quantities or their relaxations. The precision of the method reveals the effects of fibril-attached matrix, when conventional methods of mechanical testing fail.

Electrochemical studies associated with the micellization of cationic surfactants in aqueous mixtures of ethylene glycol and glycerol

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical studies associated with the micellization of cationic surfactants in aqueous mixtures of ethylene glycol and glycerolR. Palepu, H. Gharibi, D. M. Bloor, and E. Wyn-JonesCite this: Langmuir 1993, 9, 1, 110–112Publication Date (Print):January 1, 1993Publication History Published online1 May 2002Published inissue 1 January 1993https://doi.org/10.1021/la00025a025RIGHTS & PERMISSIONSArticle Views488Altmetric-Citations127LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (324 KB) Get e-Alerts Get e-Alerts

Electrochemical Behavior of the Cd(II)/Cd(Hg) System in Aqueous Mixtures of Diols and Triols

The electrochemical behavior of the Cd(II)/Cd(Hg) couple (Cd(II) concentration ) in aqueous mixtures of 1,4‐butanediol (BD) and glycerol (GL) containing has been studied. The reversible half‐wave potentials, the diffusion coefficients, and the Walden products for Cd(II) have been determined by polarography, whereas the diffusion coefficient of Cd in mercury, the transfer coefficient for Cd(II) electroreduction, and the apparent standard rate constants have been obtained by cyclic voltammetry. The standard free energies of transfer of 1 mole of Cd(II) ions from water to BD‐water and to GL‐water mixtures are found to be always negative, indicating a higher stability of Cd(II) in organic‐aqueous mixtures than in pure water. The break‐up of these values into electrostatic and chemical contributions shows that all organic‐aqueous mixtures used here are more basic than pure water, and that Cd(II) solvation increases with the mole fraction of BD or GL. The structural properties of the liquid mixtures are analyzed using the Walden products at different BD or GL levels. The changes in the kinetics of the Cd(II)/Cd(Hg) system with solvent composition are discussed in terms of existing models. Results obtained are compared with those previously reported in aqueous mixtures of ethylene glycol and 1,2‐propanediol.

Activation Parameters of Bromoacetate–Thiosulfate Reaction in Ethylene Glycol–Water Mixtures

Abstract The activation parameters for the reaction between bromoacetate (\barR) and S2O32− ions in water and aqueous mixtures of ethylene glycol (5–50% by weight) have been evaluated from the rate constants, corresponding to zero ionic strength, at 15, 25, and 35 °C. The standard free energies of transfer (ΔGtr°) of the reacting ions and hence of the transition state (ΔGtr#) from water to the mixed media at 25 °C have been determined from the measured solubilities of AgR, TlCl, and Tl2S2O3 in the different media, using the reported values of ΔGtr° of Ag+ and Cl− ions. Attempts have been made to interpret the kinetic results in the light of solvent properties and free energies of transfer. Although both the reacting ions are destabilized, on adding glycol to the medium, the larger destabilization of the transition state, arising from decreased dielectric constant as well as solvating capacity of the medium, outweighs the combined effects on the reactants leading to reduced reaction rates.

Medium effects on activation parameters on alkaline hydrolysis of 2-carbomethoxypropionate ion in aqueous mixtures of ethylene glycol

The standard free energies of transfer [Formula: see text] of the 2-carbomethoxypropionate ion (R−) have been determined from the solubilities of the silver salt (AgR) in water and six aqueous mixtures of ethylene glycol (1–60%) at 25 °C, using the literature values of [Formula: see text] of Ag+. Utilizing these values of the R− ion as well as the literature values of [Formula: see text] of the OH− ion, combined with the experimental values of ΔG≠ for the alkaline hydrolysis of R− ion, the corresponding transfer parameters of the transition states [Formula: see text] for the hydrolysis reaction in aquo-glycolic media at 25 °C have been calculated. Attempts have been made to correlate the rates and activation parameters with the transfer quantities and solvent properties.

Determination of absolute transfer free energies of hydroxyl ion from water to aqueous 2-methoxy ethanol

Absolute standard free energies of transfer ΔGt0 of OH− from water to aqueous mixtures of 2-methoxy ethanol (ME) have been evaluated at 298.15 K by combining the apparent transfer free energies of the lyate ion that were obtained from the standard emf's of the double cell:[Formula: see text]and that from the autoionization constants of these mixed solvents determined by use of the cell comprising H2– and Ag–AgCl electrodes. The required ΔGt0 values of K+ and H+ were determined earlier using the well-known tetraphenyl arsonium tetraphenyl boride (TATB) reference electrolyte method. These values and their non-Born type contributions in particular, are found to be increasingly positive in water-rich compositions, indicating that the relative stabilization of OH− and the acidity of the mixed solvents decrease with increasing cosolvent composition. These, when compared with those in aqueous mixtures of ethylene glycol and 1,2-dimethoxy ethane, are found to lie intermediate between the latter solvent systems conforming to what is expected from the structural and electronic features of the cosolvents.

Forced convective boiling in vertical tubes for saturated pure components and binary mixtures

AbstractOver 1000 sets of data for forced convective boiling of distilled water, ethylene glycol and aqueous mixtures of ethylene glycol are reported. Most of these data were taken in the annular flow regime. These data indicate a previously unrecognized Prandtl number effect on the boiling heat transfer for both pure components and mixtures. A significant reduction in the heat transfer coefficient is observed for mixtures attributable to mass transfer effects. An expression is developed which accounts for both of these effects and correlates the experimental data to within a mean deviation of 14.9%. This correlation reduces to the standard Chen correlation for pure fluids with Prandtl numbers close to unity.