Solvation and association of urea in aqueous solutions and mixtures of water with 1‐propanol

Hawlicka, Ewa; Grabowski, Roman

doi:10.1002/bbpc.19940980610

Cited by 8 publications

(3 citation statements)

References 34 publications

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“…In accordance with this, the present results show that the presence of urea in water does not seem to influence the activity of NaCl in the solution. Hawlicka and Grabowski [12] also reported the hydrodynamic radius to be independent of the urea concentration, indicating that urea does not affect the water structure. Taken together, the evidence suggests that the interaction between Na + and Clions and water is not influenced by the presence of urea.…”

Section: Discussionmentioning

confidence: 96%

Studies on Constituents of Moisturizers: Water-Binding Properties of Urea and NaCl in Aqueous Solutions

Miettinen

Johansson²,

Gobom³

et al. 1999

Skin Pharmacol Physiol

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A water content of about 10% in the horny layer is necessary for softness and pliability of this part of the epidermis. In conditions with dry skin, emollients of different types are used. It is important that solid data are collected about the effect of the ingredients of emollients and moisturizers. Urea has since long been used in the treatment of dry skin. In the present report, the mixture of urea and sodium chloride has been analyzed with respect to its effect on the water vapor pressure in concentrated solutions. The depression of the water vapor pressure by NaCl and urea was found to be additive. Thus, the decrease in water vapor pressure in aqueous solution of urea-NaCl mixtures can be estimated by adding the decrease of water vapor pressure caused by dissolving the pure compounds. The results indicate that urea and NaCl in aqueous solution do not interact strongly and are, therefore, compatible in moisturizing preparations. They can, therefore, both be expected to be effective in mixtures giving a better than one of them alone.

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Section: Discussionmentioning

confidence: 96%

Studies on Constituents of Moisturizers: Water-Binding Properties of Urea and NaCl in Aqueous Solutions

Miettinen

Johansson²,

Gobom³

et al. 1999

Skin Pharmacol Physiol

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“…1,2 Many experimental [3][4][5][6][7][8][9] and theoretical [10][11][12][13][14][15] studies have focused on determining the variation in urea and water aggregation ͑or structure͒ with urea concentration in an effort to relate these changes to the corresponding denaturation effects. Different conclusions concerning the ability of urea to promote water structure are found depending on the technique used ͑see Ref.…”

Section: Introductionmentioning

confidence: 99%

Cavity formation and preferential interactions in urea solutions: Dependence on urea aggregation

Weerasinghe¹,

Smith²

2003

The Journal of Chemical Physics

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A series of models for 8 M urea solutions was investigated using molecular dynamics simulations. The models differed only in their charge distributions and displayed various degrees of urea aggregation. The relationship between urea aggregation and the thermodynamics of the solution was established using Kirkwood-Buff theory. It was observed that high urea aggregation resulted in lower predicted values for the solution activity, and that Kirkwood-Buff theory provided a sensitive test for the properties of a particular force field. The free energy for formation of repulsive cavities in the different solutions was also investigated. The free energy was more unfavorable than in pure water, but independent of the extent of urea aggregation. However, the preferential exclusion of urea from the cavities was very sensitive to the degree of urea aggregation and varied by more than an order of magnitude in response to changes in the activity derivatives. A simple explanation for these observations is presented.

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“…Self-diffusion measurements [23][24][25] have shown that in aqueous solutions the molecules of higher alcohols, n-propanol and tert-butanol, behave also like non-polar solutes. Their hydration shells, which may be treated as stable molecular aggregates, consist of more than 20 water molecules.…”

Section: Introductionmentioning

confidence: 99%

Hydration and association in solutions of tetraalkylammonium iodides

Kuba¹,

Hawlicka²

2003

Phys. Chem. Chem. Phys.

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Conductivity, self-diffusion coefficient and viscosity were measured at 298 K for tetraalkylammonium iodides in aqueous solutions, 0.5 M urea solutions and mixtures of water with tert-butanol. The molar conductivity was analysed via the Fuoss-Hsia equation. The limiting molar conductivity, the separation of ions forming the ion pairs and the association constants were determined. In all studied systems the association of opposite ions was weak, but contact ion pairs were present. The hydrodynamic radii of ions, determined from the self-diffusion coefficients, were used to compute the dynamic hydration numbers. As expected, the dynamic hydration numbers were noticeably smaller than the static numbers, because they represented the water molecules located inside the R 4 N + ions, between the alkyl chains. Addition of tert-butanol reduced the hydration of Me 4 N + and, probably, Bu 4 N + ions, but induced aggregation of Bu 4 N + cations only.

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Solvation and association of urea in aqueous solutions and mixtures of water with 1‐propanol

Cited by 8 publications

References 34 publications

Studies on Constituents of Moisturizers: Water-Binding Properties of Urea and NaCl in Aqueous Solutions

Studies on Constituents of Moisturizers: Water-Binding Properties of Urea and NaCl in Aqueous Solutions

Cavity formation and preferential interactions in urea solutions: Dependence on urea aggregation

Hydration and association in solutions of tetraalkylammonium iodides

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