Aqueous Mixtures Of Dimethylsulfoxide Research Articles

Study of sertraline solubility, solvent effect, and modeling in the aqueous mixtures of dimethyl sulfoxide or diethylene glycol monoethyl ether at several temperatures and its use in the formulation of nanosuspensions

The solubility profile of a weakly water-soluble drug of sertraline (SRT) at the temperature range of 298.2–318.2 K under atmospheric pressure, in the binary aqueous mixtures of dimethyl sulfoxide (DMSO) and diethylene glycol monoethyl ether (DEGMEE) was measured using a shake-flask method. As a result, SRT was discovered to have the maximum solubility in DMSO among investigated solvent systems. The obtained solubility values were correlated by utilizing cosolvency models, including the Jouyban-Acree-van't Hoff and Jouyban-Acree models, and the mean relative deviations were computed in order to evaluate the precision of these equations. Additionally, using the van't Hoff and Gibbs formulas at Thm, the parameters of apparent thermodynamics (Gibbs energy, entropy, and enthalpy) of SRT in the saturated mixtures were calculated. According to these solubility results, SRT nanosuspensions, which had a mean particle size of under 200 nm, were formulated in DMSO and water as a solvent combination. Therapeutic development could be significantly improved by implementing solubilization strategies for enhancing the bioavailability of medicines that are only weakly water-soluble, according to the results of the experimental and statistical assessment of solubility.

Solubility, Preferential Solvation, and Solvent Effect of Micoflavin in Aqueous Mixtures of Dimethylsulfoxide, Isopropanol, Propylene Glycol, and Ethanol

The saturated thermodynamic solubilities of micoflavin in four mixtures of dimethyl sulfoxide (DMSO, 1) + water (2), isopropanol (1) + water (2), propylene glycol (PG, 1) + water (2), and ethanol (...

Phenformin in aqueous co-solvent mixtures of N,N-dimethylformamide, ethanol, N-methylpyrrolidone and dimethyl sulfoxide: Solubility, solvent effect and preferential solvation

The equilibrium mole fraction solubility of phenformin in four co-solvent mixtures of N,N-dimethylformamide (DMF) + water (2), ethanol (1) + water (2) and N-methylpyrrolidone (NMP, 1) + water (2) at temperatures from 278.15 K to 323.15 K and dimethyl sulfoxide (DMSO) (1) + water (2) at temperatures from 293.15 K to 323.15 K were determined via the saturation shake-flask technique. The maximum solubility values were observed in the neat co-solvents of DMF (DMSO, NMP and ethanol). Through the Jouyban-Acree model, the phenformin solubility in the four solvent mixtures was well correlated attaining RAD values less than 3.21% and RMSD values less than 4.84 × 10−4. To describe how solvent affect the solubility, the obtained solubility data were introduced into the linear solvation energy relationships model by taking the cavity term and KAT parameters as solvent’s descriptors. It was shown that the cavity term and hydrogen bond acidity of solvent play the key role on the solubility variation in aqueous DMF, DMSO, ethanol and NMP mixtures. What's more, the quantitative values for local mole fractions of DMSO (DMF, ethanol or NMP) and water around the drug phenformin were calculated by the Inverse Kirkwood–Buff integrals method based on solubility data. Phenformin was preferentially solvated by water in the DMSO/DMSO (1) + water (2) mixtures with compositions 0 < x1 < 0.20 and NMP (1) + water (2) mixture with compositions 0 < x1 < 0.16; while for the ethanol (1) + water (2) mixture with compositions 0.25 < x1 < 1, phenformin is preferentially solvated ethanol.

Solubility temperature and solvent dependence and preferential solvation of citrus flavonoid naringin in aqueous DMSO mixtures: an experimental and molecular dynamics simulation study

This study describes the thermodynamics of dissolution of flavonoid naringin in different aqueous solutions of dimethyl sulfoxide (DMSO) containing 0–100% (w/w) under atmospheric pressure and over a temperature range of 298.15 to 325.15 K.

Thermodynamics of DL-alanine solvation in water-dimethylsulfoxide mixtures at 298.15 K

In this study we mainly discuss the transfer Gibbs free energy ΔGt0(i) and ΔSt0(i)entropy of DL-alanine at 298.15 K and consequently the involved chemical transfer free energy (ΔGt,ch0(i)) and entropy (TΔSt,ch0(i)) in aqueous mixtures of dimethylsulfoxide are discussed to clarify the solvation chemistry of DL-alanine. For the evaluation of these energy terms, solubility of this amino acid has been measured by formol titrimetry at five equidistant temperatures i.e., from 288.15 to 308.15 K in different composition of this mixed solvent system. The various solvent parameters as well as thermodynamic parameters like molar volume, density, dipole moment and solvent diameter of this solvent system have also been reported here. The chemical effects of the transfer Gibbs energies (ΔGt,ch0(i)) and entropies of transfer (TΔSt,ch0(i)) have been obtained after elimination of cavity effect and dipole-dipole interaction effects from the total transfer energies. Here the chemical contribution of transfer energetics of DL-alanine is mainly guided by the composite effects of increased dispersion interaction, basicity effect and decreased acidity, hydrogen bonding effects, hydrophilic hydration and hydrophobic hydration of aqueous DMSO mixtures as compared to that of reference solvent, water.

Solubility ofdl-serine anddl-phenylalanine in aqueous mixtures of dimethyl sulfoxide and solvation thermodynamics

Solvation thermodynamic data ofdl-serine anddl-phenylalanine in aqueous mixtures of dimethylsulfoxide at 298.15 K were determined from solubility measurement.

Micellization of Cetyldiethylethanolammonium Bromide in Mixed Aqueous Organic Solvents

The micellization of cetyldiethylethanolammonium bromide has been studied in binary aqueous mixtures of dimethyl sulfoxide, dimethyl formamide, acetonitrile, methanol and tetrahydrofuran at 298–320 K using conductometric technique. Thermodynamics of micellization, i.e., Gibbs free energy (), enthalpy (), and entropy (), have been obtained from temperature dependence of critical micelle concentration (CMC). The CMC and degree of counterion ionization (α), values increases with increase in temperature and volume percentage of the aqueous-organic solvent mixtures.

Micellization behavior of [C 16-12-C 16], 2Br − gemini surfactant in binary aqueous-solvent mixtures

The micellization behavior of bis cationic gemini surfactant, N, N′-dihexadecyl- N, N, N′, N′-tetramethyl-1,12-dodecanediammonium dibromide [C 16H 33N +(CH 3) 2-(CH 2) 12-N +(CH 3) 2C 16H 33, 2Br −] has been studied in binary aqueous mixtures of dimethyl sulfoxide, methanol, 1,4-dioxane, glycerol and ethylene glycol by conductivity and surface tension measurements at 300 K. The critical micellar concentration, degree of micelle ionization ( α), surface excess concentration ( Г max), minimum surface area per molecule of surfactant ( A min), Gibbs free energy of micellization ( Δ G m ° ) , the surface pressure at cmc ( π cmc), and the Gibbs energy of adsorption ( Δ G ad ° ) of the gemini surfactant have also been determined. The cmc, α, A min increases where as ( Δ G m ° ) , Г max, and π cmc decreases with increasing volume percentage of the solvents in the solvent–water binary mixture. The interfacial properties of the gemini surfactant, solute–solute, solvent–solute interactions and the effectiveness of a surface-active molecule in binary solvent systems have been discussed.

Preferential Solvation of Ions in Mixed Solvents. 5. The Alkali Metal, Silver, and Thallium(I) Cations in Aqueous Organic Solvents According to the Inverse Kirkwood-Buff Integral (IKBI) Approach

The inverse Kirkwood-Buff integral (IKBI) approach is applied, as far as the relevant data exist in the literature, to the preferential solvation of Li+, Na+, K+, Rb+, Cs+, Ag+, and Tl+ in aqueous mixtures of methanol, ethanol, 1,2-ethanediol (EG), acetonitrile, formamide, N,N,-dimethylformamide (DMF), N,N,N′,N′,N″,N″-hexamethyl phosphoric triamide (HMPT), and dimethyl sulfoxide (DMSO). In aqueous EG and formamide the preferential solvation is very small. Water is the preferred solvent in the solvation shells in aqueous methanol, ethanol and acetonitrile (except for Ag+ in the latter solvent) but the co-solvent is preferred in aqueous mixtures of DMF, HMPT, and DMSO over most or all of the composition range. For the latter three mixtures the larger donicity of the co-solvents causes their preference, whereas where water is preferred over other protic solvents, it is the small size of the water molecules that appears to be the cause.

A conductometric study of dimethylsulfoxide effect on micellization of sodium dodecyl sulfate in dilute aqueous electrolyte solutions

Abstract Critical micelle concentrations (CMCs) of sodium dodecyl sulfate (SDS) have been determined in aqueous mixtures of dimethylsulfoxide (DMSO) between 25 and 45 °C and at very low NaBr concentration range (0.0025–0.03 mol dm−3). The ability of NaBr to lower the CMC in water is inhibited by DMSO below ∼0.014 mol dm−3 of NaBr. However, the contribution of DMSO in regard to its effect upon micellization process of SDS in aqueous electrolyte solutions have been discussed in terms of the observed behavior of thermodynamic properties, such as entropy (ΔSm°), free energy (ΔGm°) and enthalpy (ΔHm°). In particular, we discuss counterion binding as revealed by different experimental conditions. The data suggest mass action effect and salt-induced increase in micelle size with concomitant reduction in charge density of Stern-layer. These observations point to the counterion solvation effect of DMSO in addition to the loss of hydrophobic interactions due to strong intermolecular interactions.

Ostwald Concentration Coefficients of Acetonitrile in Aqueous Mixed Solvents: A New, Rapid Method for Measuring the Solubilities of Volatile Solutes

The Ostwald concentration coefficients of acetonitrile in aqueous methanol, propan-1-ol, 2-methylpropan-2-ol (tert-butyl alcohol), 1,4-dioxane, and dimethyl sulfoxide have been measured by determining the acetonitrile concentrations in the liquid and vapor phases by gas chromatography. The method described is self-calibrating and allows the rapid determination of gas solubilities. It is found that the acetonitrile solubility varies nonlinearly, and nonmonotonically, in the mixed solvents, passing through maxima in the aqueous alcohol and 1,4-dioxane systems and showing a shallow minimum in the aqueous dimethyl sulfoxide mixtures.

Some Insight into the Physical Basis of the Cryoprotective Action of Dimethyl Sulfoxide and Ethylene Glycol

In the determination of the solid–liquid phase equilibria in the aqueous mixtures of dimethyl sulfoxide (Me2SO) and ethylene glycol (EG) one often encounters the problem of equilibrium crystallization. In the present report the above aqueous solutions are equilibrated for crystallization in a dielectric cell during which the dielectric method is used for monitoring the extent of crystallization. The melting temperatures are then measured by using the dielectric technique in combination with the differential scanning calorimeter. The equilibrium phase diagram of Me2SO is found to be eutectic with two compounds formed of water and Me2SO in the ratio of 3:1 and 2:1. In the case of EG solutions it is eutectic with a 1:1 compound formation. It is suggested that the greater depression of the freezing point of water due to the complex formation and hence the attendant increase in the viscosity near the freezing point is the reason for the sluggish crystallization in these solutions. The variation of the glass transition temperature with composition is also examined in the above solutions along with the aqueous solutions of a number of other cryoprotectants. The glass-forming tendency of these solutions is discussed in terms of complex formation. An attempt is made to distinguish between good and bad glass-forming additives in terms of complex formation and ice clathrate formation.

Autoprotolysis in aqueous organic solvent mixtures. Water/dipolar protophilic solvent binary systems

The autoprotolysis of binary aqueous mixtures of dimethyl sulfoxide, acetonitrile, acetone, tetrahydrofuran and 1,4-dioxan is studied. It is demonstrated that except for solvent mixtures very rich in water, the autoprotolysis is produced by proton transfer from water to the dipolar organic solvent. Only in water rich mixtures the autoionization of water contributes appreciably to autoprotolysis. It is also suggested that the so-called autoprotolysis constant or ionic product of these pure organic solvents is in fact, produced by proton transfer from the very small amounts of water present in the medium to the organic solvent. Equations and parameters are presented that allow calculation of the autoprotolysis constant for any solvent composition at 25 °C. The variation of the autoprotolysis constant with temperature is also studied for dimethyl sulfoxide/water and acetone/water mixtures.

Solvent effect on preferred protonation sites in nicotinate and isonicotinate anions

Potentiometric determinations of the two successive acidities of nicotinic and isonicotinic acids (AH2+) have been carried out in aqueous dimethyl sulfoxide mixtures containing up to 95% Me2SO by volume. In both systems, the results reveal that the addition of Me2SO induces a proton transfer from the pyridinium ring to the carboxylate group, the tautomeric equilibrium between the neutral forms of the two acids being displaced toward the zwitterionic form (AH±) in aqueous solution, but toward the molecular form (AH°) in Me2SO. An analysis of the data by means of Hammett relationships previously established for benzoic acids over the whole range of H2O/Me2SO mixtures allowed the four microscopic acidity constants as well as the tautomeric equilibrium constant KTpertaining to the complete ionization scheme of the two acids to be determined. At 20 °C, there are equal populations of the tautomeric AH° and AH±species in the mixtures containing 38 and 47% Me2SO for the nicotinic and isonicotinic systems, respectively. Hammett relationships describing the ionization behaviour of a number of substituted pyridinium cations in H2O/Me2SO mixtures are also discussed. Possible reasons accounting for the peculiar effects exerted by the NH2, CONH2, and COOH substituents on the process are suggested. Key words: nicotinic and isonicotinic acids, substituted pyridines, acidities, tautomeric equilibrium, protonation sites, water – dimethyl sulfoxide mixtures.

Ester Cleavage by Cyclodextrins in Aqueous Dimethyl Sulfoxide Mixtures. Substrate Binding versus Transition State Binding

Ester Cleavage by Cyclodextrins in Aqueous Dimethyl Sulfoxide Mixtures. Substrate Binding versus Transition State Binding

Reactions of carbonyl compounds in basic solutions. Part 20. Mechanism of the base-catalysed rearrangement of symmetrically substituted benzils

Rate coefficients have been measured for the base-catalysed rearrangement of a series of symmetrically 2,2′-, 3,3′- and 4,4′-disubstituted benzils at 30.0 and 60.0 °C in 70%(v/v) aqueous dimethyl sulfoxide (DMSO), as well as at 40.0 and 50.0 °C for benzil itself. The enthalpies and entropies of activation have been evaluated. For benzil itself, rate coefficients have been measured at 60.0 °C in a series of aqueous DMSO and dioxane mixtures. The effects of meta/para-substitution have been assessed by means of the Hammett equation to give, using σ(and not 2σ), a ρ value of about 5.7. The role of these effects for the migrating and non-migrating phenyl groups have been separated. The steric effects from ortho-substitution have been evaluated. The limiting conditions for the observation of the base-catalysed rearrangement and two types of fission for benzils are delineated. The results are discussed in terms of mechanistic paths for the rearrangement and fission processes and the structures of the transition states.

Contribution of water to free energy of hydrolysis of pyrophosphate.

The energy of hydrolysis of phosphate compounds varies depending on whether they are in solution or bound to the catalytic site of enzymes. With the purpose of simulating the conditions at the catalytic site, the observed equilibrium constant for pyrophosphate hydrolysis (Kobsd) was measured in aqueous mixtures of dimethyl sulfoxide, ethylene glycol, or polymers of ethylene glycol. The reaction was catalyzed by yeast inorganic pyrophosphatase at 30 degrees C. All the cosolvents used promoted a decrease of Kobsd. Polymers of ethylene glycol were more effective than dimethyl sulfoxide or ethylene glycol in decreasing Kobsd. The higher the molecular weight of the polymer, the lower the value of Kobsd. A decrease in Kobsd from 346 M (delta G degree obsd = -3.5 kcal mol-1) to 0.1 M (delta G degree obsd = 1.3 kcal mol-1) was observed after the addition of 50% (w/v) poly(ethylene glycol) 8000 to a solution containing 0.9 mM MgCl2 and 1 mM Pi at pH 8.0. The association constants of Pi and pyrophosphate for H+ and Mg2+ were measured in presence of different ethylene glycol concentrations in order to calculate the Keq for hydrolysis of different ionic species of pyrophosphate. A decrease in all the Keq was observed. The results are interpreted according to the concept that the energy of hydrolysis of phosphate compounds depends on the different solvation energies of reactants and products.

ChemInform Abstract: TRANSFER FREE ENERGIES OF FLUORIDE ION IN AQUEOUS MIXTURES OF SOME ORGANIC SOLVENTS

AbstractDie Freien Standardenergien für den Transfer von KF aus H2O in wäßrige Gemische von DMSO, DMF, MeCN, 1,2‐Dimethoxyethan (DME) und 2‐Methoxyethanol (ME) werden bei 25°C aus EMK‐Messungen an der Doppelkette A bestimmt.

Transfer Free Energies of Fluoride Ion in Aqueous Mixtures of Some Organic Solvents

Abstract Standard free energies of transfer, ΔGt°, of potassium fluoride (KF) from water to aqueous mixtures of dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), acetonitrile (ACN), 1,2-dimethoxyethane (DME), and 2-methoxyethanol (ME) have been determined at 25 °C from emf measurements performed on the double cell: Pb(Hg)–PbF2/KF(m), solvent/K(Hg)/KF(m), water/PbF2–Pb(Hg). ΔGt° values of F− were obtained from these values using the corresponding values of K+, as obtained earlier by use of tetraphenylarsonium tetraphenylborate reference electrolyte assumption. In each solvent system ΔGt°(F−) values are found to be increasingly positive with cosolvent composition reflecting the pronounced destabilization of F− and their relative order : DME&amp;gt;DMSO≥DMF&amp;gt;&amp;gt;ACN≈ME conforms to what is expected from the relative ‘aproticity’ of the dipolar aprotic cosolvents and that induced in the protic ME by the possible intramolecular H-bonding. The observed larger destabilization of F− compared to OH− in ME–water system has been attributed to the H-bonding effect of the protic cosolvent ME and the reverse behaviour in DME–water and DMSO–water systems to the absence of such effect of these cosolvents. Moreover, tests of Feakins-type extrapolation for assigning individual ion contribution using ΔGt°(KF) values along with those of other potassium halides, provided some important reflections on the inadequacy of such plots made without the data points of F−.

Transfer free energies of some ions from water to dimethylsulfoxide-water and urea-water mixtures

The standard free energies of transfer (ΔGto) of some electrolytes from water to aqueous mixtures of dimethylsulfoxide (DMSO) and of urea have been split into the contribution from individual ions by use of the reference electrolyte Ph4AsBPh4 (RE), where Ph=phenyl. For each of the solvents, ΔGto(Ph4AsBPh4) was determined from the solubility products of the salts KBPh4, Ph4AsPi, and KPi, where Pi=picrate ion. The observed ΔGto(i) values for the individual ions are strikingly different from the corresponding values obtained by the simultaneous extrapolation (SE) procedure reported earlier.