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Yoshikata Koga - One of the best experts on this subject based on the ideXlab platform.

  • the effect of 2 2 2 trifluoroethanol on water studied by using third derivatives of gibbs energy g
    Journal of Molecular Liquids, 2016
    Co-Authors: Hiroyo Ohgi, Peter Westh, Hiroshi Imamura, Kazuki Yonenaga, Takeshi Morita, Keiko Nishikawa, Yoshikata Koga
    Abstract:

    Abstract We determined the excess Partial Molar Enthalpy and the excess Partial Molar volume, H TFE E , V TFE E , of 2,2,2-trifluoroethanol (TFE) in TFE-H 2 O at 25.0 °C. We then evaluate the TFE-TFE interactions in terms of Enthalpy and volume, H TFE-TFE E and V TFE-TFE E , graphically without resorting to any model dependent fitting functions. Both model-free third derivatives indicate that TFE is a hydrophobic solute and that as other hydrophobic alkyl mono-ols there are three distinct mixing schemes, Mixing Schemes I, II, and III in their aqueous solutions. The relative strength in hydrophobicity between TFE and tert -butylalcohol (TBA), for example, gave a mixed message within the behavior of these third derivative quantities. We thus applied the 1-propanol (1P) probing methodology (Koga, Y. Phys. Chem. Chem. Phys. 2013, 15 , 14548) that utilizes the fourth derivative in effect, and quantified the degree of hydrophobicity of TFE. It turned out that TFE is a stronger hydrophobe than 1P and ethanol (ET), and has approximately the same hydrophobicity as TBA within the estimated uncertainty. These findings were compared with the ability reported in literature to denature β-lactoglobulin and to induce α-helices in melittin in their aqueous solutions.

  • third derivative thermodynamic quantities of aqueous tetrahydrofuran at 25 c
    Journal of Molecular Liquids, 2015
    Co-Authors: Koh Yoshida, Peter Westh, Akira Inaba, Motohiro Nakano, Yoshikata Koga
    Abstract:

    Abstract We measured the excess chemical potential, μETHF, the excess Partial Molar Enthalpy and entropy of solute tetrahydrofuran (THF), HETHF and SETHF, in THF–H2O at 25 °C. Using these second derivatives of G, we graphically evaluated the third derivative quantities; the enthalpic, entropic THF–THF interaction functions, HETHF–THF, and SETHF–THF. Using the literature density data, the effect of THF on the excess Partial Molar volume of THF, VETHF–THF, was also evaluated. Furthermore, we directly determined the Partial Molar entropy-volume cross fluctuation density of THF, δ T H F S V , another third derivative quantity. By comparing the mole fraction dependence patterns of these third derivative quantities between the present THF–H2O with what we thought to be the weakest member of a hydrophobic mono-ol series, methanol (ME), we suggest that in spite of its larger non-polar surface area, THF is as amphiphilic as ME. A quantitative characterization and any difference between THF and ME ought to wait for characterization by the 1-propanol probing methodology developed by us [PCCP 15(2013) 14548-14565].

  • excess chemical potential and Partial Molar Enthalpy of 2 iso butoxyethanol in aqueous solution at 20 c
    Thermochimica Acta, 2003
    Co-Authors: Candy M W Cheung, Kitty P Y Chan, Yoshikata Koga
    Abstract:

    Vapour pressures were determined at 20 °C for aqueous 2-iso-butoxyethanol (iBE). Partial pressures and hence, the excess chemical potentials of iBE were calculated by the Boissonnas method. Excess Partial Molar enthalpies were measured, and the excess Partial Molar entropies of iBE were then calculated at 20 °C. These data and their mole fraction dependence indicated that there are three mixing schemes operative, in the same way as in aqueous 2-n-butoxyethanol (nBE) studied extensively by us. The details of each mixing schemes are identical, but the locus of the transition between mixing schemes I and II occurs at a smaller mole fraction than for aqueous nBE. This suggests that iBE is a stronger hydrophobic solute than nBE, which is consistent with the common understanding.

  • excess Partial Molar Enthalpy of 1 propanol in 1 propanol acetone or tetramethyl urea h2o at 25 c effect of acetone or tetramethyl urea on h2o
    Fluid Phase Equilibria, 2001
    Co-Authors: Daniel Heng Chi Chen, Yoshikata Koga, Allen P Liu
    Abstract:

    Abstract Excess Partial Molar enthalpies of 1-propanol, H1PE, were measured at 25°C in ternary 1-propanol–acetone (or tetramethyl urea)–H2O, with various initial compositions of acetone (or tetramethyl urea). They were determined accurately and in small increments in mole fraction of 1-propanol. It was therefore, possible to take a derivative of H1PE with respect to the amount of 1-propanol, n1P, H1P–1PE≡N(∂H1PE/∂n1P). The changes in the mole fraction dependence of H1PE and hence, H1P–1PE caused by adding a third component, acetone or tetramethyl urea, were compared with the results of analogous earlier studies with urea and 2-propanol as a third component. The effects of acetone and tetramethyl urea were found qualitatively the same. The CH3 group in each compound works as a typical hydrophobic moiety and enhances the hydrogen bond network of H2O in the immediate vicinity of solute molecule (“iceberg formation”) with concomitant reduction of the hydrogen bond probability of H2O. The CO group on the other hand, seems to reduce the degree of fluctuation in the hydrogen bond strength in the bulk H2O away from the solute.

  • additive effect of 1 propanol and 2 propanol on molecular organization of h2o in the water rich region excess chemical potential Partial Molar Enthalpy and volume of 1 propanol in 1 propanol 2 propanol h2o at 25 c
    Bulletin of the Chemical Society of Japan, 2001
    Co-Authors: Jianhua Hu, Wesley Minda Chiang, Daniel Heng Chi Chen, Charles A. Haynes, Peter Westh, Yoshikata Koga
    Abstract:

    Excess chemical potential, μ1PE, Partial Molar Enthalpy, H1PE and volume of 1-propanol, V1PE, were determined as a function of mole fraction of 1-propanol, x1P, in mixed solvents of aqueous 2-propanol with various initial mole fraction of 2-propanol, x2P0. The 1-propanol–1-propanol interaction functions, H1P–1PE ≡ N(∂H1PE/∂n1P), and V1P–1PE ≡ N(∂V1PE/∂n1P), were evaluated by graphical differentiation. The x1P-dependence of all these quantities indicates that 1-propanol and 2-propanol modify the molecular organization of H2O in the same and additive manner in the water-rich region. The additive effect of 1-propanol and that of 2-propanol are in the ratio of (0.07/0.08).

Peter Westh - One of the best experts on this subject based on the ideXlab platform.

  • the effect of 2 2 2 trifluoroethanol on water studied by using third derivatives of gibbs energy g
    Journal of Molecular Liquids, 2016
    Co-Authors: Hiroyo Ohgi, Peter Westh, Hiroshi Imamura, Kazuki Yonenaga, Takeshi Morita, Keiko Nishikawa, Yoshikata Koga
    Abstract:

    Abstract We determined the excess Partial Molar Enthalpy and the excess Partial Molar volume, H TFE E , V TFE E , of 2,2,2-trifluoroethanol (TFE) in TFE-H 2 O at 25.0 °C. We then evaluate the TFE-TFE interactions in terms of Enthalpy and volume, H TFE-TFE E and V TFE-TFE E , graphically without resorting to any model dependent fitting functions. Both model-free third derivatives indicate that TFE is a hydrophobic solute and that as other hydrophobic alkyl mono-ols there are three distinct mixing schemes, Mixing Schemes I, II, and III in their aqueous solutions. The relative strength in hydrophobicity between TFE and tert -butylalcohol (TBA), for example, gave a mixed message within the behavior of these third derivative quantities. We thus applied the 1-propanol (1P) probing methodology (Koga, Y. Phys. Chem. Chem. Phys. 2013, 15 , 14548) that utilizes the fourth derivative in effect, and quantified the degree of hydrophobicity of TFE. It turned out that TFE is a stronger hydrophobe than 1P and ethanol (ET), and has approximately the same hydrophobicity as TBA within the estimated uncertainty. These findings were compared with the ability reported in literature to denature β-lactoglobulin and to induce α-helices in melittin in their aqueous solutions.

  • third derivative thermodynamic quantities of aqueous tetrahydrofuran at 25 c
    Journal of Molecular Liquids, 2015
    Co-Authors: Koh Yoshida, Peter Westh, Akira Inaba, Motohiro Nakano, Yoshikata Koga
    Abstract:

    Abstract We measured the excess chemical potential, μETHF, the excess Partial Molar Enthalpy and entropy of solute tetrahydrofuran (THF), HETHF and SETHF, in THF–H2O at 25 °C. Using these second derivatives of G, we graphically evaluated the third derivative quantities; the enthalpic, entropic THF–THF interaction functions, HETHF–THF, and SETHF–THF. Using the literature density data, the effect of THF on the excess Partial Molar volume of THF, VETHF–THF, was also evaluated. Furthermore, we directly determined the Partial Molar entropy-volume cross fluctuation density of THF, δ T H F S V , another third derivative quantity. By comparing the mole fraction dependence patterns of these third derivative quantities between the present THF–H2O with what we thought to be the weakest member of a hydrophobic mono-ol series, methanol (ME), we suggest that in spite of its larger non-polar surface area, THF is as amphiphilic as ME. A quantitative characterization and any difference between THF and ME ought to wait for characterization by the 1-propanol probing methodology developed by us [PCCP 15(2013) 14548-14565].

  • additive effect of 1 propanol and 2 propanol on molecular organization of h2o in the water rich region excess chemical potential Partial Molar Enthalpy and volume of 1 propanol in 1 propanol 2 propanol h2o at 25 c
    Bulletin of the Chemical Society of Japan, 2001
    Co-Authors: Jianhua Hu, Wesley Minda Chiang, Daniel Heng Chi Chen, Charles A. Haynes, Peter Westh, Yoshikata Koga
    Abstract:

    Excess chemical potential, μ1PE, Partial Molar Enthalpy, H1PE and volume of 1-propanol, V1PE, were determined as a function of mole fraction of 1-propanol, x1P, in mixed solvents of aqueous 2-propanol with various initial mole fraction of 2-propanol, x2P0. The 1-propanol–1-propanol interaction functions, H1P–1PE ≡ N(∂H1PE/∂n1P), and V1P–1PE ≡ N(∂V1PE/∂n1P), were evaluated by graphical differentiation. The x1P-dependence of all these quantities indicates that 1-propanol and 2-propanol modify the molecular organization of H2O in the same and additive manner in the water-rich region. The additive effect of 1-propanol and that of 2-propanol are in the ratio of (0.07/0.08).

  • mixing scheme of aqueous butan 1 ol in the water rich region at 25 c excess chemical potential Partial Molar Enthalpy entropy and volume heat capacity compressibility and thermal expansivity
    Physical Chemistry Chemical Physics, 2000
    Co-Authors: Katsutoshi Tamura, Christa Trandum, Charles A. Haynes, Jianhua Hu, Peter Westh, Yoshikata Koga
    Abstract:

    We determined excess chemical potential, Partial Molar Enthalpy, entropy and volume, heat capacity, isothermal compressibility and thermal expansivity for aqueous butan-1-ol in the water-rich region up to the phase separation boundary at 25°C. The latter three response functions were used to calculate the mean-square fluctuation densities, which signifies the amplitude, or the intensity, of fluctuations in volume, entropy or cross (entropy–volume) fluctuations. Furthermore, we calculated the (mean-square) normalized fluctuations that are indicative of the wavelength, or the extensity, as well as the amplitude of respective fluctuations. The behaviour of these thermodynamic quantities were compared with those obtained earlier in this laboratory for aqueous methanol, ethanol, propan-1-ol, tert-butanol (tert-butyl alcohol), and 2-butoxyethanol. We conclude that in the water-rich region of aqueous butan-1-ol, mixing scheme I is operative as in other alcohols, whereby butan-1-ol molecules enhance the hydrogen bond network of H2O in their immediate vicinities with concomitant reduction of hydrogen bond probability in the bulk H2O away from solutes. However, before reaching the phase separation boundary there was no signature indicative of the transition of mixing scheme observed in other aqueous alcohols. Thus, in aqueous butan-1-ol phase separation occurs directly from mixing scheme I, without going through mixing scheme II, which we argued earlier to be a preparation stage for phase separation for the other alcohols.

Jianhua Hu - One of the best experts on this subject based on the ideXlab platform.

  • additive effect of 1 propanol and 2 propanol on molecular organization of h2o in the water rich region excess chemical potential Partial Molar Enthalpy and volume of 1 propanol in 1 propanol 2 propanol h2o at 25 c
    Bulletin of the Chemical Society of Japan, 2001
    Co-Authors: Jianhua Hu, Wesley Minda Chiang, Daniel Heng Chi Chen, Charles A. Haynes, Peter Westh, Yoshikata Koga
    Abstract:

    Excess chemical potential, μ1PE, Partial Molar Enthalpy, H1PE and volume of 1-propanol, V1PE, were determined as a function of mole fraction of 1-propanol, x1P, in mixed solvents of aqueous 2-propanol with various initial mole fraction of 2-propanol, x2P0. The 1-propanol–1-propanol interaction functions, H1P–1PE ≡ N(∂H1PE/∂n1P), and V1P–1PE ≡ N(∂V1PE/∂n1P), were evaluated by graphical differentiation. The x1P-dependence of all these quantities indicates that 1-propanol and 2-propanol modify the molecular organization of H2O in the same and additive manner in the water-rich region. The additive effect of 1-propanol and that of 2-propanol are in the ratio of (0.07/0.08).

  • mixing scheme of aqueous butan 1 ol in the water rich region at 25 c excess chemical potential Partial Molar Enthalpy entropy and volume heat capacity compressibility and thermal expansivity
    Physical Chemistry Chemical Physics, 2000
    Co-Authors: Katsutoshi Tamura, Christa Trandum, Charles A. Haynes, Jianhua Hu, Peter Westh, Yoshikata Koga
    Abstract:

    We determined excess chemical potential, Partial Molar Enthalpy, entropy and volume, heat capacity, isothermal compressibility and thermal expansivity for aqueous butan-1-ol in the water-rich region up to the phase separation boundary at 25°C. The latter three response functions were used to calculate the mean-square fluctuation densities, which signifies the amplitude, or the intensity, of fluctuations in volume, entropy or cross (entropy–volume) fluctuations. Furthermore, we calculated the (mean-square) normalized fluctuations that are indicative of the wavelength, or the extensity, as well as the amplitude of respective fluctuations. The behaviour of these thermodynamic quantities were compared with those obtained earlier in this laboratory for aqueous methanol, ethanol, propan-1-ol, tert-butanol (tert-butyl alcohol), and 2-butoxyethanol. We conclude that in the water-rich region of aqueous butan-1-ol, mixing scheme I is operative as in other alcohols, whereby butan-1-ol molecules enhance the hydrogen bond network of H2O in their immediate vicinities with concomitant reduction of hydrogen bond probability in the bulk H2O away from solutes. However, before reaching the phase separation boundary there was no signature indicative of the transition of mixing scheme observed in other aqueous alcohols. Thus, in aqueous butan-1-ol phase separation occurs directly from mixing scheme I, without going through mixing scheme II, which we argued earlier to be a preparation stage for phase separation for the other alcohols.

Daniel Heng Chi Chen - One of the best experts on this subject based on the ideXlab platform.

Charles A. Haynes - One of the best experts on this subject based on the ideXlab platform.

  • additive effect of 1 propanol and 2 propanol on molecular organization of h2o in the water rich region excess chemical potential Partial Molar Enthalpy and volume of 1 propanol in 1 propanol 2 propanol h2o at 25 c
    Bulletin of the Chemical Society of Japan, 2001
    Co-Authors: Jianhua Hu, Wesley Minda Chiang, Daniel Heng Chi Chen, Charles A. Haynes, Peter Westh, Yoshikata Koga
    Abstract:

    Excess chemical potential, μ1PE, Partial Molar Enthalpy, H1PE and volume of 1-propanol, V1PE, were determined as a function of mole fraction of 1-propanol, x1P, in mixed solvents of aqueous 2-propanol with various initial mole fraction of 2-propanol, x2P0. The 1-propanol–1-propanol interaction functions, H1P–1PE ≡ N(∂H1PE/∂n1P), and V1P–1PE ≡ N(∂V1PE/∂n1P), were evaluated by graphical differentiation. The x1P-dependence of all these quantities indicates that 1-propanol and 2-propanol modify the molecular organization of H2O in the same and additive manner in the water-rich region. The additive effect of 1-propanol and that of 2-propanol are in the ratio of (0.07/0.08).

  • mixing scheme of aqueous butan 1 ol in the water rich region at 25 c excess chemical potential Partial Molar Enthalpy entropy and volume heat capacity compressibility and thermal expansivity
    Physical Chemistry Chemical Physics, 2000
    Co-Authors: Katsutoshi Tamura, Christa Trandum, Charles A. Haynes, Jianhua Hu, Peter Westh, Yoshikata Koga
    Abstract:

    We determined excess chemical potential, Partial Molar Enthalpy, entropy and volume, heat capacity, isothermal compressibility and thermal expansivity for aqueous butan-1-ol in the water-rich region up to the phase separation boundary at 25°C. The latter three response functions were used to calculate the mean-square fluctuation densities, which signifies the amplitude, or the intensity, of fluctuations in volume, entropy or cross (entropy–volume) fluctuations. Furthermore, we calculated the (mean-square) normalized fluctuations that are indicative of the wavelength, or the extensity, as well as the amplitude of respective fluctuations. The behaviour of these thermodynamic quantities were compared with those obtained earlier in this laboratory for aqueous methanol, ethanol, propan-1-ol, tert-butanol (tert-butyl alcohol), and 2-butoxyethanol. We conclude that in the water-rich region of aqueous butan-1-ol, mixing scheme I is operative as in other alcohols, whereby butan-1-ol molecules enhance the hydrogen bond network of H2O in their immediate vicinities with concomitant reduction of hydrogen bond probability in the bulk H2O away from solutes. However, before reaching the phase separation boundary there was no signature indicative of the transition of mixing scheme observed in other aqueous alcohols. Thus, in aqueous butan-1-ol phase separation occurs directly from mixing scheme I, without going through mixing scheme II, which we argued earlier to be a preparation stage for phase separation for the other alcohols.