共查询到20条相似文献,搜索用时 15 毫秒
1.
V. I. Smirnov I. N. Mezhevoi V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(8):1245-1249
The integral enthalpies of solution of DL-α-alanylglycine and DL-α-alanyl-DL-α-alanine in water-organic solvent (acetonitrile, 1,4-dioxane, acetone, N,N-dimethylformamide, and N,N-dimethylsulfoxide) mixtures were measured at organic component concentrations x 2 = 0–0.4 mole fractions and T = 298.15 K. The standard enthalpies of solution (Δsol H°) and transfer (Δtr H°) of the peptides from water into mixed solvents were calculated. The influence of the structure and properties of solutes and mixture composition on the thermochemical characteristics of the peptides was considered. The enthalpy coefficients of pair interactions (h xy ) of DL-α-alanylglycine and DL-α-alanyl-DL-α-alanine with organic solvent molecules were calculated. The h xy values were correlated with the properties of organic solvents using the Kamlet-Taft equation. 相似文献
2.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(7):1206-1210
The integral enthalpies of solution of L-α-alanyl-L-α-alanine in water-ethanol, water-n-propanol, and water-isopropanol mixtures were measured calorimetrically at alcohol concentrations x 2 ranging from 0 to 0.4 mole fractions. The standard enthalpy of peptide solution Δsol H o and transfer Δtr H o from water into a mixed solvent were calculated. The effect of the structure and properties of peptides and mixture composition on the enthalpy characteristics is discussed. The enthalpy coefficients of pair interactions h xy between L-α-alanyl-L-α-alanine and alcohol molecules were calculated; these coefficients were positive and increased in the series ethanol, n-propanol, isopropanol. The analysis performed allowed the differences in the thermodynamic characteristics of solution of L-α-alanyl-L-α-alanine and DL-α-alanyl-DL-α-alanine in water-alcohol mixtures to be determined. 相似文献
3.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(12):2069-2073
The integral enthalpies of solution of DL-α-alanyl-DL-α-valine in water-ethanol, water-n-propanol, and water-isopropanol mixtures at alcohol concentrations x 2 = 0–0.4 mole fractions were measured calorimetrically. The enthalpies of solution of the peptide Δsol H° and transfer from water to a mixed solvent Δtr H° were calculated. The effect of the structure and properties of the peptide and mixture composition on the enthalpy characteristics of the peptide are discussed. The enthalpy coefficients of pair interactions h xy of DL-α-alanyl-DL-α-valine with alcohol molecules were calculated. It was found that they were positive and increased in the series ethanol, n-propanol, isopropanol. An analysis of the results allows the general features of changes in the thermodynamic parameters of solution of peptides of the DL-α-alanine series with different amino acid residues in water-alcohol mixtures to be established. 相似文献
4.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(9):1555-1559
The integral enthalpies of solution (T = 298.15 K) of L-α-alanyl-L-α-alanine in aqueous-organic solvents (acetonitrile, 1,4-dioxane, acetone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-diethylformamide, and N,N-dimethylsulfoxide) were measured at organic component concentrations x 2 = 0–0.3 mole fractions. The standard enthalpies of solution (Δsol H o) and transfer (Δtr H o) of the peptide from water into mixed solvents were calculated. The influence of the structure and properties of solutes and mixture composition on solute thermochemical characteristics is considered. The enthalpy pair interaction coefficients h xy between L-α-alanyl-L-α-alanine and organic solvent molecules were calculated. The linear Kamlet-Taft four-parameter equation was used to reveal correlation between the h xy values and the properties of organic solvents. 相似文献
5.
V. G. Badelin V. I. Smirnov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2017,91(1):84-88
A thermochemical study of the processes of L-proline dissolution in aqueous solutions of acetonitrile, 1,4-dioxane, acetone, dimethyl sulfoxide, nitromethane and tetrahydrofuran at Т = 298.15 K in the range of organic solvent concentrations x2 = 0–0.25 mole fractions is performed. Standard values of the enthalpies of solution and transfer of L-proline from water to mixed solvent, and the enthalpy coefficients of pairwise interactions between L-proline and molecules of organic solvents, are calculated. The effect the composition of a water–organic mixture and the structure of organic solvents have on the enthalpy characteristics of L-proline dissolution and transfer is examined. The effect the energy properties of intermolecular interactions between components of a mixed solvent has on the intermolecular interactions between L-proline and molecules of cosolvent is estimated. The correlation between the enthalpy characteristics of L-proline dissolution and electron-donor properties of organic cosolvent in aqueous solutions is determined. 相似文献
6.
A. V. Kustov V. P. Korolev 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2008,82(11):1828-1832
The solubility of L-phenylalanine and L-histidine in water at 298.15 and 318.15 K and the heat effects of solution of the amino acids at 328.15 K were determined. These results and the data obtained earlier were used to calculate all the standard thermodynamic functions of solution of the amino acids and the solubilities of L-phenylalanine and L-histidine over the temperature range 273–373 K. The selection of the form of the Δsol H o = f(T) dependence had a negligible effect on the free energies of solution and solubilities of the amino acids. This selection primarily influenced the entropy and heat capacity characteristics of the process. 相似文献
7.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(12):2087-2090
Enthalpies of solution for DL-α-alanyl-β-alanine in H2O-ethanol, H2O-1-propanol, and H2O-2-propanol mixed solvents with the alcohol mole fraction x 2 = 0–0.3 are measured at 298.15 K. Standard enthalpies of solution (Δsol H °), standard enthalpies of transfer of DL-α-alanyl-β-alanine from water to binary solvent (Δtr H °), and coefficients of enthalpies of pair interactions with alcohol molecules (h xy ) are calculated. The effect the structure and properties of alcohols and the composition of a water-alcohol mixture have on the enthalpy of dissolution for DL-α-alanyl-β-alanine are discussed. The h xy values for dipeptides of the alanine series in water-alcohol binary solvents are compared. 相似文献
8.
V. G. Badelin V. I. Smirnov 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2011,85(6):944-947
Solution enthalpies of DL-α-alanyl-DL-α-asparagine (AlaAsn) in water-formamide, water-N-methylformamide, water-N,N-dimethylformamide, and water-N,N-dimethylacetamide mixtures were measured in the range of amide mole fractions x
2 = 0–0.3. The standard enthalpies of solution (Δsol
H°) and transfer (Δtr
H°) of AlaAsn from water to the binary solvent and enthalpy coefficients of pair-wise interactions (h
xy
) of AlaAsn with amide molecules were calculated. The influence of the composition of the water-organic mixture on the enthalpy
characteristics of AlaAsn is discussed. It is shown that the enthalpy characteristics of solution and transfer of AlaAsn are
related to the structure of amides. 相似文献
9.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2013,87(11):1793-1797
Enthalpies of the dissolution of DL-α-alanyl-DL-norleucine are determined by calorimetry in aqueous solutions of formamide (FA), N-methylformamide (MFA), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA) at a concentration of amides of x 2 = 0–0.4 molar parts and T = 298.15 K. Standard values of enthalpies of dissolution Δsol H o and Δtr H o of DL-α-alanyl-DL-norleucine transfer from water to binary solvent are calculated, along with the enthalpy coefficients of pair interactions h xy of DL-α-alanyl-DL-norleucine with amide molecules. The effect of the composition of water-organic mixtures and the structure of amides on the enthalpy characteristics of dissolution and transition of DL-α-alanyl-DL-norleucine is considered. Quantitative estimates of the contributions to energy from DL-α-alanyl-DL-norleucine-amides pair interactions determined by the polarity, polarizability, and electron acceptor and electron donor ability of organic cosolvents are given using the Kamlet-Taft correlation equation. 相似文献
10.
The enthalpies of solution of dl-α-alanyl-dl-α-asparagine (AlaAsn) were measured in aqueous methanol, ethanol, 1-propanol and 2-propanol with an alcohol mole-fraction content x2 (from 0 to 0.4) at 298.15 K. The experimental results were used to calculate the enthalpies of transfer of AlaAsn from water to these mixtures as well as the enthalpy coefficients of pair-wise interactions (hxy) between AlaAsn and alcohol molecules in water, according to the McMillan–Mayer's model. The hxy values were found to be positive and increasing in a series methanol < ethanol < 1-propanol < 2-propanol. 相似文献
11.
Zaira J. Cárdenas Ovidio A. Almanza Abolghasem Jouyban William E. Acree Jr 《Physics and Chemistry of Liquids》2018,56(1):16-32
The mole fraction solubility of phenacetin (PNC) in methanol + water binary solvent mixtures at 298.15 K was determined along with density of the saturated solutions. All these solubility values were correlated with the Jouyban–Acree model. Preferential solvation parameters of PNC by methanol (δx1,3) were derived from their thermodynamic solution properties using the inverse Kirkwood–Buff integrals (IKBI) method. δx1,3 values are negative in water-rich mixtures but positive in methanol mole fraction of >0.32. It is conjecturable that in the former case the hydrophobic hydration around non-polar groups of PNC plays a relevant role in the solvation. The higher solvation by methanol in mixtures of similar cosolvent compositions and methanol-rich mixtures could be explained in terms of the higher basic behaviour of methanol. 相似文献
12.
Cveto Klofutar Mateja Ajnihar Nata?a Poklar Ulrih Darja Rudan-Tasic 《Monatshefte für Chemie / Chemical Monthly》2010,80(2):23-30
Abstract
The density, refractive index, and electrical permittivity of cyclohexylsulfamic acid in 1,4-dioxane solutions were measured at 298.15 K. The limiting apparent specific volume, refraction, and polarization were calculated from the experimental data. The electrical dipole moment of cyclohexylsulfamic acid was estimated using the Debye, Onsager, and Kirkwood equations. The dipole association of cyclohexylsulfamic acid was treated with the assumption that the dipole moment of dimeric species is zero. The dimerization constant and dipole moment of monomeric species were evaluated. 相似文献13.
《Physics and Chemistry of Liquids》2012,50(3):379-383
Experimental solubilities are reported for anthracene in six binary alkane?+?ethanol solvent mixtures at 298.15?K. The alkane solvents studied were hexane, heptane, octane, cyclohexane, methylcyclohexane and 2,2,4-trimethylpentane. Results of these measurements were used to test a mathematical representation based on the combined nearly ideal binary solvent (NIBS)/Redlich–Kister equation. For the six systems studied, the combined NIBS/Redlich–Kister equation was found to accurately describe the experimental data, with an average absolute deviation between measured and back-calculated values being approximately ±0.5%. 相似文献
14.
《Physics and Chemistry of Liquids》2012,50(6):812-818
Experimental solubilities are reported for anthracene in eight binary toluene?+?alcohol solvent mixtures at 298.15?K. The alcohol solvents studied were 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 2-propanol, 2-butanol, 2-methyl-1-propanol and 3-methyl-1-butanol. Results of these measurements were used to test a mathematical representation based on the combined nearly ideal binary solvent (NIBS)/Redlich–Kister equation. For the eight systems studied, the combined NIBS/Redlich–Kister equation was found to accurately describe the experimental data, with an average absolute deviation between the measured and back-calculated values being approximately ±0.4%. 相似文献
15.
V. I. Smirnov V. G. Badelin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2018,92(5):900-904
Enthalpies of the dissolution of DL-α-alanylglycine (AlaGly), DL-α-alanyl-DL-α-alanine (AlaAla), DL-α-alanyl-DL-α-valine (AlaVal), and DL-α-alanyl-DL-norleucine (AlaNln) in an aqueous solution of sodium dodecyl sulfate (SDS) at SDS concentration of m = 0–0.07 mol kg?1 and temperature Т = 298.15 K are measured via calorimetry. The standard values of the enthalpy of dissolution (ΔsolH m ) and the transfer of dipeptides (ΔtrH m ) from water to aqueous SDS solutions are calculated using the experimental data. The dependences of ΔsolH m and ΔtrH m the SDS concentration at a constant concentration of dipeptide are established. Thermochemical characteristics of the transfer of AlaGly, AlaAla, AlaVal, and AlaNln in the investigated range of SDS concentrations are compared. The results are interpreted by considering ion–ion, ion–polar, and hydrophobic–hydrophobic interactions between SDS and dipeptide molecules. 相似文献
16.
Fleming Martínez Abolghasem Jouyban William E. Acree Jr 《Physics and Chemistry of Liquids》2017,55(3):291-303
Preferential solvation parameters of etoricoxib in several aqueous cosolvent mixtures were calculated from solubilities and other thermodynamic properties by using the IKBI method. Cosolvents studied were as follows: 1,4-dioxane, N,N-dimethylacetamide, 1,4-butanediol, N,N-dimethylformamide, ethanol and dimethyl sulfoxide. Etoricoxib exhibits solvation effects, being the preferential solvation parameter δx1,3, negative in water-rich and cosolvent-rich mixtures but positive in mixtures with similar proportions of both solvents. It is conjecturable that the hydrophobic hydration in water-rich mixtures plays a relevant role in drug solvation. In mixtures of similar solvent proportions where etoricoxib is preferentially solvated by the cosolvents, the drug could be acting as Lewis acid with the more basic cosolvents. Finally, in cosolvent-rich mixtures the preferential solvation by water could be due to the more acidic behaviour of water. Nevertheless, the specific solute–solvent interactions in the different binary systems remain unclear because no relation between preferential solvation magnitude and cosolvent polarities has been observed. 相似文献
17.
Takayoshi Kimura Tasunori Suzuki Keisuke Takata Akina Soga Yutsa Nomoto Tadashi Kamiyama Yousuke Nakai Hideo Matsui Masao Fujisawa 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1467-1474
The molar excess enthalpies of eight systems of butylamines + propanols were determined at 298.15 K using a twin-microcalorimeter. All excess enthalpies were exothermic and large. An equilibrium constant K 1 expressed in terms of mole fractions and standard thermodynamic properties of formation (Δf H, Δf G, Δf S) of 1:1 complex were evaluated by ideal mixtures of monomeric molecules and their associated complexes. Concentration dependence of the FT-Raman spectrum showed systematic changes of bands. Spectroscopic considerations based on this and ab initio calculations on molecules were performed at the Mp2/6-311G(d,p) level of theory. Interaction energies between butylamine and propanol were calculated by the supermolecular and NBO methods. The results were discussed with previous results to clarify the steric and positional effect of the amino and hydroxyl group. 相似文献
18.
Enthalpies of mixing of ethanol solution of R- and S-enantiomers of limonene in large concentration have been measured at 298.15 K. The enthalpies of mixing were negligibly small
for all concentrations. Enthalpies of mixing showed negative in less than 30 mol%, but positive in more than the high concentration
of limonenes. The heterochiral solutions were more stable than each of the homochiral solutions in dilute solutions. The concentration
dependence on enthalpies of mixing in dilute concentration of less than 10 mol% was much sharper in inclination than the dense
solutions limonene. 相似文献
19.
Piotr Szterner 《Journal of Thermal Analysis and Calorimetry》2009,98(1):337-341
The enthalpies of solution $ \Updelta_{sol}^{{}} H_{m}^{{}} $ of polymorphic forms I and II of theophylline in water at 298.15 K using the isoperibol solution calorimeter have been determined in the range of concentration (0.311–1.547) · 10?3 /mol · kg?1. The enthalpies of hydration $ \Updelta_{hyd}^{{}} H_{m}^{o} $ were determined from the experimentally obtained the enthalpies of solution for aqueous solutions and previously determined enthalpies of sublimation $ \Updelta_{s}^{g} H_{m}^{o} . $ 相似文献