单硫酸卡那霉素、乙醇及其混合物在水中的稀释热

本文测定了25℃的单硫酸卡那霉素水溶液和卡那霉素-乙醇水溶液的稀释热. 同时对乙醇水溶液的稀释热也重新进行了测定.     

Quantitative description of the hydrophobic effect: the enthalpic contribution

A new method of experimental determination of the hydrophobic effect enthalpy is proposed. The method is based on regarding the hydration enthalpy as the sum of the nonspecific hydration enthalpy, specific hydration enthalpy, and the hydrophobic effect enthalpy. The hydrophobic effect enthalpies of noble and simple substance gases, alkanes, arenes, and normal aliphatic alcohols are determined. For the noble gases and alkanes, the hydrophobic effect enthalpy is found to be negative and independent of the size of molecule. For aromatic hydrocarbons, it is positive and grows up with the size of the hydrocarbon. The hydrophobic effect enthalpies of normal aliphatic alcohols are determined by assuming that the specific interaction enthalpies of alcohols in water and in methanol are equal. The hydrophobic effect enthalpy values for the aliphatic alcohols (-10.0 +/- 0.9 kJ.mol(-1)) were found to be close to the alkanes hydrophobic effect enthalpies (-10.7 +/- 1.5 kJ.mol(-1)).     

Enthalpy of cooperative hydrogen bonding in the complexes of triethyl- and tri-<Emphasis Type="Italic">n</Emphasis>-butylamines with alcohols: Effect of the alkyl chain length

The measurements of enthalpies of triethylamine and tri-n-butylamine dissolution in aliphatic alcohols and, vice versa, of aliphatic alcohols in amines were carried out. Enthalpies of specific interactions in the studied systems were calculated. The enthalpy of specific interaction determined in the alcohol medium, are significantly less than those obtained at dissolving alcohols in amines. The mechanism of specific interaction of amines with alcohols is discussed. Enthalpies of cooperative hydrogen bonds of tertiary amines with alcohol clusters are calculated. The dependences between the enthalpies of hydrogen bond and the spatial structure of interacting molecules are revealed.     

Studies of hydrophobic bonding in aqueous alcohols: Enthalpy measurements and model calculations

The coefficients which measure the contribution of a pair of solute molecules to the excess enthalpy have been measured in water at 25°C for all pairs of alcohols which can be formed from the series methyl to n-butyl plus t-butyl as well as for ethanol with some of the higher alcohols and with the n-alkyl sulfonates through octyl. The methylene-group contribution to these coefficients is readily identifiable in suitable cases. These data and the corresponding free-energy and volume coefficients, where they are known, are analyzed in terms of amodel which specifies the core repulsion and solvation-layer overlap terms in the potential for the interaction of two solute molecules. The latter term has an adjustable parameter, the so-called Gurney free-energy parameter which is adjusted for each solute pair to fit the free-energy data. Its temperature and pressure derivatives are adjusted to fit the enthalpy and volume data, respectively. These parameters are compared with the corresponding thermodynamic coefficients of solvation as far as possible.This paper was presented at the symposium, The Physical Chemistry of Aqueous Systems, held at the University of Pittsburgh, Pittsburgh, Pennsylvania, June 12–14, 1972, in honor of the 70th birthday of Professor H. S. Frank.A portion of the talk presented at the H. S. Frank Symposium has been published else-where. The discussion section at the end of this paper pertains mainly to that portion.     

Thermochemistry of Aniline Solution in Isomeric Butyl Alcohols and Their Aqueous Solutions

The enthalpies of solution (_s H ⁰) of aniline in isomeric butyl alcohols and their aqueous solutions at 25°C were determined. The dissolution of aniline becomes more endothermic with increasing content of alcohol in aqueous solution. The enthalpy coefficients of pair interaction alcohol-aniline in aqueous solution were calculated. This interaction is enhanced in the order tert-butanol-sec-butanol-iso-butanol-n-butanol. The correlations of these characteristics with physicochemical properties of solvents were revealed.     

Excess enthalpies of aqueous ternary solutions of urea and polyols at 25°C

The heats of dilution of nine ternary solutions of urea and polyols have been determined at 25°C. Excess enthalpies and their virial coefficients h _xy have been evaluated and compared with the data reported in the literature for mono- and polyfunctional alcohols and other oxygenated nonelectrolytes. The group additivity approach of Savage and Wood was applied and the contributions to the enthalpy coefficients, due to the water mediated interactions between urea and the functional groups –CH₂–, –OH, and –O– were determined. On the other hand, by using empirical combination rules among the cross- and self-enthalpic interaction coefficients it is possible to emphasize the large differences in the behavior (even in the presence of urea) of the polyols (and in particular of cyclitols) and of saccharides.     

Enthalpy characteristics of dilute solutions of acetonitrile

The enthalpies of mixing of acetonitrile with formamide,N-methylformamide,N,N-dimethylformamide, and hexamethylphosphoric triamide were measured in the temperature interval from 283.15 to 328.15 K. The enthalpy coefficients of binary and ternary interactions were calculated by the methods of the McMillan-Mayer theory. The contributions to the enthalpy of solution due to the formation of a cavity in the solvent, Δ_cav H°, and those due to the interaction of the solute with the solvent, Δ_int H°, were determined. The enthalpies of the specific and non-specific solvation of acetonitrile in the corresponding amides were calculated. Specific interactions were found to contribute the most to the solvation enthalpy of acetonitrile. The obtained values were compared with analogous values for solutions of acetonitrile in water and alcohols. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 289–293, February, 1997.     

Thermodynamic characteristics,structure, and interactions of L-proline in aqueous solutions of alcohols and urea

The enthalpies of dissolution of imino acid L-proline in aqueous solutions of methanol, 2-propanol, ethylene glycol, glycerin, and urea are measured by the calorimetric method at 313.15 K. Enthalpic parameters of the interaction of L-proline with nonaqueous components are calculated and compared with the data at 298.15 K. It is found that the sign of the heat capacity parameter of the pair and ternary interactions depends on whether the nonaqueous solvent component is a destroyer or stabilizer of the water structure. Partial molar heat capacities of proline in mixed solvents are obtained by the integral dissolution heat method. Temperature changes in the reduced enthalpy and entropy of the proline solution are determined at an increase in the temperature from 298 K to 313 K. It is shown that there is entropyenthalpy compensation at temperature changes in the characteristics during dissolution.     

含醇溶液的热力学研究I.超额焓模型

提出了一个醇与烃混合的热力学模型,据此,得到了一个简单的超额焓方程, 它由物理和化学贡献两部分组成。这个方程具有一定的通用性,能够推广到其它含 醇溶液。方程不仅能满意地用来描述超额焓与组成间的关系,而且还能显示组分间 的相互作用。     

Lanthanide transport in stabilized zirconias: interrelation between ionic radius and diffusion coefficient

The diffusion of all stable lanthanides was measured both in calcia stabilized zirconia (CSZ) and in yttria stabilized zirconia (YSZ) in the temperature range between 1,286 and 1,600 degrees C. The lanthanide diffusion coefficients obtained increase with increasing ionic radius. The experimental activation enthalpy of diffusion is near 6 eV for CSZ and between 4 and 5 eV for YSZ and is not strongly affected by the type of lanthanide. The results were correlated with defect energy calculations of the lanthanide diffusion enthalpy using the Mott-Littleton approach. An association enthalpy of cation vacancies with oxygen vacancies of about 1 eV (96 kJ/mol) was deduced in the case of CSZ, while there is no association in the case of YSZ. Furthermore, the change in diffusion coefficients can be correlated to the interaction parameter for the interaction between the lanthanide oxide with zirconia: The higher the interaction parameter, the higher the lanthanide diffusion coefficient.     

醇类在惰性溶剂中的缔合溶液热力学

用Kretschmer-Wiebe模型结合Hildebrand-Scatchard公式处理含醇体系的活度系γ_i,得到醇类的自身缔合平衡常数K_A和氢键生成焓h_A。在烷烃溶剂中,K_A与烷烃的碳原子数关系不显著。在同一溶剂中,K_A依下列顺序减小: 甲醇>乙醇>正丙醇>正丁醇; 正丙醇>异丙醇; 正丁醇>异丁醇>仲丁醇>叔丁醇。所测醇类的h_A的平均值为:k_A=-24.3±0.6kJmol~(-1),与醇类的碳原子数及异构关系不显著计算出醇类-角鲨烯体系偏离Hildebrand-Scatchard公式的相互作用常数l_(AB),l_(AB)均为负值,|l_(AB)|依下列顺序减小: 甲醇>乙醇>正丙醇>正丁醇; 正丙醇>异丙醇; 正丁醇>异丁醇>仲丁醇>叔丁醇     

Dielectric Relaxation and Thermodynamic Studies of Binary Mixtures of 2-Nitrotoluene with Primary and Secondary Alcohols at Different Temperatures

The dielectric complex spectra of 2-nitrotoluene with primary or secondary alcohol binary mixtures were studied over the frequency range of 10 MHz to 20 GHz for the whole solute mole fraction range at four different temperatures. An unusual suppression phenomenon was observed in the real and imaginary parts of the mixture complex spectrum, which are smaller than those for the pure alcohols, at low solute concentrations. The dielectric constant and dielectric relaxation time values were obtained by fitting the complex dielectric spectrum data to the single Debye model using a non-linear least squares method. The dielectric constant of mixtures decrease with the increasing mole fraction of 2NT in both the primary alcohols and secondary alcohols; the dielectric relaxation time decreases for all the five binary systems. Using the dielectric data, derived dielectric parameters, namely: the excess dielectric constant, excess inverse relaxation time, effective Kirkwood correlation factor, molar activation enthalpy and molar activation entropy, were calculated. The non-linear variation of permittivity (?₀) reveals the change in size and shape of hetero-molecular complex due to intermolecular H-bond interaction. The negative variation of the excess permittivity constant confirms that the dipoles form multimer structures with anti-parallel ordering of unlike dipoles. The molar activation enthalpy was found to be higher at 0.2 mol fraction of 2NT for primary alcohol binary system. To confirm the molecular function group interaction, a FT-IR spectroscopy study was carried out at 298 K. The FT-IR analysis confirmed the formation of hydrogen bonds between the hydrogen atom of hydroxyl groups of the alcohols and the oxygen atom of nitro groups of 2NT in the binary mixtures.     

气液色谱法测量醇类在惰性溶剂中的无限稀热力学函数

用气液色谱法测量了在不同温度下C_1～C_4醇类的各种异构物在C_(16)～C_(23)正构烷烃、角鲨烷,和角鲨烯中的无限稀活度系数γ_i,偏摩尔过量焓、偏摩尔过量熵。在各种溶剂中γ_i、均大于1,在同一溶剂中γ_i依下列次序减小: 甲醇>乙醇>正丙醇>正丁醇; 正丙醇>异丙醇; 正丙醇>异丁醇>仲丁醇>叔丁醇同一种醇在角鲨烯中的γ_i较在角鲨烷中为低。异构醇类的低于正构醇类。所测的有随的增加而增加的趋势。     

Solvophobic effects in binary nonaqueous mixtures

In the framework of the Mc Millan-Mayer theory, the enthalpy, volume, and heat capacity coefficients of binary and ternary interactions of amides, alcohols, and acetonitrile in water and nonaqueous solvents were obtained at various temperatures. No pronounced regularities in changes in the coefficients of multiple interactions observed in aquous solutions were found for nonaqueous solutions of the substances studied. None of the considered coefficients can be used as a criterion for solvophobicity. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1587–1591, September, 1997.     

QM/MM Studies on Cyclodextrin-Alcohol Interaction

The main objective of this study is to provide an insight into the interactions involved during adsorption of the alcohols on β-CD composite nanostructured membrane. Interactions between β-cyclodextrin (β-CD) and alcohols (methanol, ethanol and butanol) are studied using the QM/MM method. Magnitude of interaction energies show that the alcohols are adsorbed on the membrane. In addition, the thermochemical analysis suggests that the formation of these host-guest complexes is enthalpy driven.     

Enantioselective effects in the association behaviour of optically active alcohols

The association behaviour of four optically active secondary alcohols with chiral C atoms in the α-position was investigated by means of IR spectroscopy and calorimetry CCl₄ was used as a solvent. As compared to the racemic compounds, the corresponding optically active alcohols have slightly higher concentrations of free OH groups, i.e. lower degrees of association, but somewhat higher enthalpy of association. Consequently, the H-bonding of racemic alcohols is favoured by entropy. Differences have been found also in the absorption coefficients of the associated OH groups. Optically active solvents exert some influence on the association behaviour of optically active alcohols. No differences could be observed in the H-bonding of optically active monocarboxylic acids, as compared with the racemic ones     

Prediction of the vaporization enthalpy based on modified Randič indices. II. Polyatomic alcohols

The vaporization enthalpy of polyatomic alcohols with different structures under normal conditions is calculated using a modified Randič method. The vaporization enthalpy of polyatomic alcohols is shown to largely depend on the number of hydrogen bonds formed by alcohols.     

Enthalpy of solution of phenoxyalcohols solubilized in aqueous sodium dodecylsulfate and hexadecyltrimethylammonium bromide solutions

The enthalpy of solution of phenoxy 2-ethanol, 1 phenoxy,-3 propanol and benzylalcohol was determined at 25 °C in aqueous sodium dodecylsulfate and hexadecyltrimethylammonium bromide solution, up to 0.2 mol/kg surfactant concentration. Using the pseudo-phase model, the standard enthalpy of transfer and the partition coefficient of the alcohols between micelle and water are calculated. The latter quantity is found to be systematically larger when derived from enthalpy than from free energy measurements. Using the so-called compensation plot, the solution thermodynamics of aromatic and aliphatic alcohols in aqueous sodium dodecylsulfate and in the octane+water systems are compared. Aromatic alcohols display an anomalous behavior in the octane+ water system but not in the micellar one.The standard enthalpy of solution of various alcohols presents, when plotted against hexadecyltrimethylammonium bromide concentration, a shoulder in the region around 0.05 mol/kg; a discussion is presented on the evidence for alleged micellar structural changes in aqueous micellar systems.     

Enthalpies of solution and dilution of butanol and pentanol in dodecyltrimethylammonium bromide micellar solutions

The enthalpies of solution and of dilution of 1-butanol and 1-pentanol were measured in micellar solutions of dodecyltrimethylammonium bromide by systematically changing the concentration of alcohols and surfactant. The enthalpies of solution at infinite dilution of alcohols at each surfactant concentration were evaluated from a linear plot. This quantity increases with surfactant concentration (up to 0.8m) with a curvature which depends on the alcohol alkyl chain length. The difficulties arising for a quantitative treatment of both the enthalpies of dilution and of solution at finite alcohol concentrations are discussed. The dependence on the surfactant concentration of the standard enthalpies of solution and the enthalpies of dilution for m0 are rationalized. From the resulting equations the distribution constant, standard enthalpy of transfer, standard enthalpy of solution, and the alcohol-alcohol interaction parameter in the micellar phase are evaluated. The enthalpies of transfer obtained using this technique agree well with those previously reported from enthalpies of mixing. The distribution constants also agree with those reported in the literature from several approaches: mixing enthalpies, partial molar volumes, and the dependence of the cmc on added alcohol.     

Phase behavior of binary mixtures composed of ethylene carbonate and various organic solvents

Phase behaviors of the binary mixtures composed of ethylene carbonate (EC) and aliphatic alcohols, ω-phenyl alcohols, and alkylbenzenes were investigated. In addition, heat of solution of EC into these organic solvents was measured. The EC/methanol and EC/ethanol systems gave homogeneous solution at the temperature above their liquidus lines, while the mixtures of EC and alcohols with longer alkyl chain showed a miscibility gap in a liquid phase and provided the monotectic-type phase diagram. The liquid–liquid phase separation region expanded with the increase in the alkyl chain length. A similar phase behavior was also observed for the mixtures of EC and alkylbenzenes. On the other hand, the EC mixtures with ω-phenyl alcohols showed no miscibility gap in a liquid phase at least up to 4-phenylbutan-1-ol which has C4 alkyl chain intervening between phenyl and hydroxyl groups. This result demonstrates that both of the hydroxyl and phenyl groups act to facilitate the mixing of aliphatic compounds with EC. The phase behavior of these EC mixtures was analyzed applying the modified regular solution model in which the pair interaction energy was regarded as free energy. The model calculation with the use of heat of solution of EC at infinite dilution as the pair interaction enthalpy reproduced well both of the experimentally obtained liquidus line and mutual solubility curve as well as monotectic point.