共查询到20条相似文献,搜索用时 15 毫秒
1.
Aiju Chen Min Liu Yan Zheng Dezhi Sun Bingquan Wang Xu Wang 《Journal of solution chemistry》2013,42(11):2213-2228
7-Hydroxycoumarin exhibits antioxidative, lipoxygenase inhibitive and anti-tumourigenic effects. Density and viscosity measurements have been carried out for the solutions of 7-hydroxycoumarin in mixture solvents of water and ethanol or 1-propanol at T = (293.15, 298.15, 303.15, 308.15 and 313.15) K. The measured data have been used to evaluate apparent molar volumes (V ? ), limiting apparent molar volumes ( $ V_{\phi }^{0} $ ), viscosity B-coefficients of the Jones–Dole equation and variation of B with temperature (dB/dT). The values of $ V_{\phi }^{0} $ and B-coefficients are positive and pass through their corresponding maxima at about 18 mol·kg?1 ethanol molality and 20 mol·kg?1 1-propanol molality, respectively. Besides, the values of $ V_{\phi }^{0} $ and B-coefficients decrease with increasing temperature. Molar refractive indices (R D) of the ternary solutions at the temperature of 298.15 K have also been determined from measured refractive indices (n D). There is an obvious increase of R D with increasing molality of the solvent. These parameters have been interpreted in terms of solute–solvent interactions and structure making/breaking ability of components in the aqueous solution. The temperature and concentration dependences of the weak interactions in the solution systems have also been discussed. 相似文献
2.
Dadashev R. Kh. Dzhambulatov R. S. Mezhidov V. Kh. Elimkhanov D. Z. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(5):1041-1042
Russian Journal of Physical Chemistry A - Concentration dependences of the surface tension and density of solutions of three-component acetone–ethanol–water systems and the bounding... 相似文献
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4.
Jaka Horvat Marija Bešter-Rogač Cveto Klofutar Darja Rudan-Tasic 《Journal of solution chemistry》2008,37(9):1329-1342
The viscosities of aqueous solutions of lithium, sodium, potassium, rubidium and caesium cyclohexylsulfamates were measured
at 293.15, 298.15, 303.15, 313.15 and 323.15 K. The relative viscosity data were analyzed and interpreted in terms of the
Kaminsky equation, η
r=1+Ac
1/2+Bc+Dc
2. The viscosity A-coefficient was calculated from the Falkenhagen-Dole theory. The viscosity B-coefficients are positive and relatively large. Their temperature coefficient ∂
B/∂
T is negative or near zero for lithium and sodium salts whereas for potassium, rubidium and caesium salts it is positive. The
viscosity D-coefficient is positive. This was explained by the size of the ions, structural solute–solute interactions, hydrodynamic
effect, and by higher terms of the long-range Debye-Hückel type of forces. From the viscosity B-coefficients the thermodynamic functions of activation of viscous flow were calculated. The limiting partial molar Gibbs
energy of activation of viscous flow of the solute was divided into contributions due to solvent molecules and the solute
in the transition state. The activation energy of the solvent molecules was calculated using the limiting Gibbs energy of
activation for the conductance of the solute ions. The activation energy of the solvent molecules was then discussed in terms
of the nature of the alkali-metal ions and their influence on the structure of water. The limiting activation entropy and
enthalpy of the solute for activation of viscous flow were interpreted by ion-solvent bond formation or breaking in the transition
state of the solvent. The hydration numbers of the investigated electrolytes were calculated from the specific viscosity of
the solutions. 相似文献
5.
Densities and viscosities have been determined for binary mixtures of isopropyl acetate or isobutyl acetate with o-xylene, m-xylene, p-xylene and ethyl benzene at (303.15 and 313.15) K for the entire composition range. The excess molar volumes and deviations
in viscosity have been calculated from the experimental values. The variations of these parameters, with composition of the
mixtures and temperature, have been discussed in terms of molecular interactions occurring in these mixtures. Further, the
viscosities of these binary mixtures were calculated theoretically from their corresponding pure component data by using empirical
relations, and the results were compared with the experimental findings. 相似文献
6.
Reza Tahery 《Journal of solution chemistry》2017,46(5):1152-1164
Surface tensions (σ) for the binary mixtures chlorocyclohexane + tetrahydrofuran and chlorobenzene + tetrahydrofuran at 298.15 K and 1.013 bar have been determined as a function of the mole fraction. In order to analyze the surface tension behavior, the extended Langmuir (EL) and Shereshefsky models were used and parameters of the models were obtained for these mixtures. The standard Gibbs energy of adsorption (\( - \Delta G^{\circ} \)) was calculated using both models. The Gibbs energy change for replacing 1 mol of solute with 1 mol of solvent in the surface region (?G S), and the excess number of molecular layers of solute in the surface region, were calculated using Shereshefsky’s model. The magnitudes of ?G S and \( - \Delta G^{\circ} \) are discussed in terms of the nature and type of intermolecular interactions in the binary mixtures. 相似文献
7.
8.
Heats of solution, Δsol
H
m
, of L-cysteine, L-serine and L-asparagine amino acids have been measured at different concentrations of aqueous ethanol,
propanol and 2-propanol at 298.15 K using solvation calorimetry. These data are compared with the results reported earlier
for L-alanine in ethanol. The enthalpic coefficients, h
xy
, of the solute-organic cosolvent pair interaction in water have been obtained from the McMillan-Mayer approach and the data
have been interpreted in terms of various interactions and changes in solvent structure. 相似文献
9.
10.
The densities of l-alanine and l-serine in aqueous solutions of N,N-dimethylformamide (DMF) have been measured at 298.15 K with an Anton Paar Model 55 densimeter. Apparent molar volumes $ (V_{\phi } ) $ ( V ? ) , standard partial molar volumes $ (V_{\phi }^{0} ) $ ( V ? 0 ) , standard partial molar volumes of transfer $ (\Updelta_{\text{tr}} V_{\phi }^{0} ) $ ( Δ tr V ? 0 ) and hydration numbers have been determined for the amino acids. The $ \Updelta_{\text{tr}} V_{\phi }^{0} $ Δ tr V ? 0 values of l-serine are positive which suggest that hydrophilic–hydrophilic interactions between l-serine and DMF are predominant. The –CH3 group of l-alanine has much more influence on the volumetric properties and the $ \Updelta_{\text{tr}} V_{\phi }^{0} $ Δ tr V ? 0 have smaller negative values. The results have been interpreted in terms of the cosphere overlap model. 相似文献
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12.
Densities, partial molar volumes, and viscosities of aqueous solutions of betaine have been measured at 5, 10, 15, 20, 25,
30, 37, and 45 °C over the concentration range 0.05 to 5.0 mol⋅L−1. The partial molar volumes show that betaine exists partly as a monohydrate and partly in its anhydrous form. The proportion
of the anhydrous form increases with increasing temperature. Also, an associated form of betaine appears in concentrated betaine
solutions, possibly with water as a bridging group. The significance of the viscosity B-coefficient is discussed. The signs of B
st, the increment of the viscosity B-coefficients arising from structural changes of water, are negative and the signs of dB/dT, the temperature derivative of B, are positive. These results show that betaine is a water structure breaker especially at lower temperatures, and this effect
decreases to insignificance at higher temperatures. The ionization equilibria of betaine were investigated in aqueous 0.5 mol⋅L−1 and 1.0 mol⋅L−1 NaNO3 at 5, 15, 25, and 37 °C by a potentiometric method. Using the least-square computer program SUPERQUAD, the complex forms
are deduced to be betanium BH, bis(betanium) BHB, and bis(betaine) B2 or bis(betaine)hydrate BH2OB. 相似文献
13.
Enthalpies of dilution of N,N′-hexamethylenebisacetamide in water and aqueous alkali halide solutions at the concentration
of 0.150 mol⋅kg−1 (approximately the concentration of physiological saline) have been determined by isothermal titration microcalorimetry at
298.15 K. The enthalpic interaction coefficients in the solutions have been calculated according to the excess enthalpy concept
based on the calorimetric data. The values of enthalpic pair-wise interaction coefficients (h
2) of the solute in aqueous solutions of different salts were discussed in terms of the different alkali salt ions and weak
interactions of the diluted component with coexistent species as well as the change in solvent structure caused by ions. 相似文献
14.
Enthalpies of solution and apparent molar volumes have been determined for propionamide in aqueous methanol, ethanol and propanol solutions at 298.15 K using a C-80 microcalorimeter and a DMA60/602 vibrating-tube digital densimeter. The enthalpic and volumetric interaction coefficients have been calculated. Using the present results along with results from previous studies for formamide, the pair-interaction coefficients are discussed from the perspective of dipole-dipole and structural interactions. In addition, the triplet interaction coefficients are interpreted by using the solvent-separated association mechanism. 相似文献
15.
Mónia A. R. Martins Olga Ferreira Lubomír Hnědkovský Ivan Cibulka Simão P. Pinho 《Journal of solution chemistry》2014,43(5):972-988
In this work, the partial molar volumes of glycine and dl-alanine in aqueous solutions of ammonium sulfate at 0.0, 0.1, 0.3, 0.7, and 1.0 mol·kg?1 are determined between 278.15 and 308.15 K. Transfer volumes were obtained, which are larger for glycine than dl-alanine. On the contrary, the hydration numbers are higher for dl-alanine than glycine, and dehydration of the amino acids is observed with increasing temperature or salt molality. The data suggest that interactions between ion and charged/hydrophilic groups are predominant and, by applying the methodology proposed by Friedman and Krishnan, it was concluded that they are mainly pairwise. A group-contribution scheme has been successfully applied to the pairwise volumetric interaction coefficient. Finally, the dehydration effect on glycine, alanine and serine in the presence of different electrolytes has been rationalized in terms of the charge density and a parameter accounting for the cation’s hydration. 相似文献
16.
Xiao-ming Chen Hai-yang Yang Ping-sheng He 《化学物理学报(中文版)》2009,22(5):541-544
PVP/SDS complex was applied as a probe to study the interaction between β-cyclodextrin (β-CD) and sodium dodecyl sulfate (SDS) in aqueous solution. It has been found that a critical concentration, namely cs, exists in the relative viscosity of solution containing PVP/SDS complex versus β-CD concentration plot. As the β-CD concentration is less than cs, the relative viscosity of solution decreases sharply by adding β-CD into solution successively. On the other hand, as the β-CD concentration is greater than cs, the relative viscosity of solution increases gradually by adding β-CD into solution. The decrease of the relative viscosity of solution containing PVP/SDS in the presence of β-CD is just due to the inclusion complex of β-CD with the guest molecule SDS. And, this inclusion interaction takes down SDS from the PVP chains in solution. The ratio of the host molecule β-CD to the guest molecule SDS can be calculated from Cs. In our experiment the inclusion ratio of β-CD to SDS is 1/1. The further experimental results indicate that cs is associated with SDS but free from PVP in PVP/SDS complex. However, the inclusion ratio of β-CD to SDS has proved to be independent of either SDS or PVP in PVP/SDS complex. 相似文献
17.
Gavin R. Hedwig 《Journal of solution chemistry》2009,38(10):1315-1331
Solution densities over the temperature range 288.15 to 313.15 K have been measured for aqueous solutions of the nucleosides
inosine, 2′-deoxyinosine, and 2′-deoxyguanosine, from which the partial molar volumes of the solutes at infinite dilution,
V
2o, were obtained. The partial molar expansions for the nucleosides at infinite dilution and 298.15 K, E
2o {E
2o=(∂
V
2o/∂
T)
p
}, were derived from the V
2o results. The V
2o values at 298.15 K for the two sugars D-ribose and 2-deoxyribose also have been determined. The partial molar heat capacities
at infinite dilution for all the solutes, C
p,2o, have been determined at 298.15 K. These V
2o,E
2o, and C
p,2o results are critically compared with all of the results available from the literature, and the use of group additivity to
evaluate these solution thermodynamic properties for the sparingly soluble nucleoside guanosine is explored. 相似文献
18.
The enthalpies of solution of L- and D-valines in water-ethanol, water-n-propanol, and water-i-propanol mixtures were measured calorimetrically at 298.15 K at alcohol mole fractions, x
2, ranging up to 0.4. Enthalpies of transfer, Δtr
H°, from water to aqueous alkanol were calculated for each of the system studied. The enthalpic coefficients, h
xy
, of the solute-cosolvent pair-wise interaction in water proved to be positive and increasing in the series: ethanol, n-propanol, and i-propanol. It was shown that both the nature of the amino acid L–L- and D–D-isomerization and dimensions of linear or branched cosolvent molecules define the energetics of interaction between valine
and alkanol molecules. 相似文献
19.
The apparent molar volumes (V
φ
) of glycine, L-alanine and L-serine in aqueous 0 to 4 mol⋅kg−1 N-methylacetamide (NMA) solutions have been obtained by density measurement at 298.15 K. The standard partial molar volumes
(Vf0)V_{\phi}^{0}) and standard partial molar volumes of transfer (DtrVf0)\Delta_{\mathrm{tr}}V_{\phi}^{0}) have been determined for these amino acids. It has been show that hydrophilic-hydrophilic interactions between the charged
groups of the amino acids and the –CONH– group of NMA predominate for glycine and L-serine, but for L-alanine the interactions
between its side group (–CH3) and NMA predominate. The –CH3 group of L-alanine has much more influence on the value of DtrVf0\Delta_{\mathrm{tr}}V_{\phi}^{0} than that of the –OH group of L-serine. The results have been interpreted in terms of a co-sphere overlap model. 相似文献
20.
Aleksandra Chodzińska Anna Zdziennicka Bronis?aw Jańczuk 《Journal of solution chemistry》2012,41(12):2226-2245
From measurements of the surface tension, density, viscosity and light scattering of aqueous solutions of methanol, ethanol and propanol at 293?K, their activity in the surface monolayer, surface excess concentration, and apparent and partial molar volume were determined. The surface excess concentration of alcohols at the water?Cair interface was determined from the Gibbs equation by using both the alcohol's activity and their molar fraction in the bulk phase and recalculated by using the Guggenheim?CAdam equation. The values of the surface excess concentration determined from the Gibbs equation were also applied to determine the standard Gibbs energy of alcohol adsorption at the water?Cair interface from Langmuir??s equation and compared to those determined from that of Aronson and Rosen. 相似文献