Thermodynamic properties of 4-tert-butyl-diphenyl oxide

The main thermodynamic functions (changes of the entropy, enthalpy, and Gibbs free energy) and functions of formation at T = 298.15 K of 4-tert-butyl-diphenyl oxide in condensed and ideal gas states were computed on the basis of experimental results obtained. The heat capacities of 4-tert-butyl-diphenyl oxide was measured by vacuum adiabatic calorimetry over the temperature range (8 to 371) K. The temperature, the enthalpy and the entropy of fusion were determined. The energy of combustion of the sample was determined by static-bomb combustion calorimetry. The saturation vapor pressures of the substance were measured by dynamic transpiration method over the temperature and pressure intervals (298 to 325) K and (0.05 to 1.2) Pa. The enthalpy of sublimation at T = 298.15 K was derived. The contribution of O-(2C_b) group (where C_b is the carbon atom in a benzene ring) into the absolute entropies of diphenyl oxide derivatives was assessed.     

The heat capacities and thermodynamic functions of some derivatives of ferrocene

The heat capacities of benzoylferrocene (BOF), C₅H₅FeC₅H₄COC₆H₅, and benzylferrocene (BF), C₅H₅FeC₅H₄CH₂C₆H₅, have been measured by the low-temperature adiabatic calorimetry in the temperature range from 6 K to 372 K. The purity benzylferrocene and thermodynamic properties – the triple point temperature and the enthalpy of fusion have been obtained. The ideal gas thermodynamic functions (changes of the entropy, enthalpy, and Gibbs free energy) of BOF and BF were derived at T = 298.15 K using the heat capacities and previously determined data on the saturation vapours pressures and the enthalpies of sublimation. The ideal gas enthalpy of formation and absolute entropy of BOF at T = 298.15 K have been obtained from quantum chemical calculations, where as the thermodynamic properties of BF have been estimated by empirical method of group equations. A good agreement between experimental and theoretical values provides an additional check of the reliability of the experimental data.     

Thermodynamic properties of tert-butylbenzene and 1,4-di-tert-butylbenzene

Heat capacities, enthalpies of phase transitions, and derived thermodynamic properties over the temperature range 5 < (T/K) < 442 were determined with adiabatic calorimetry for tert-butylbenzene (TBB) {Chemical Abstracts Service registry number (CASRN) [98-06-6]} and 1,4-di-tert-butylbenzene (DTBB) {CASRN [1012-72-2]}. A crystal to plastic crystal transition very near the triple-point temperature of DTBB was observed. New vapor pressures near the triple-point temperature are also reported for DTBB for the liquid and crystal states. These new measurements, when combined with published results, allow calculation of the thermodynamic properties for the ideal gas state for both compounds. The contribution of the tert-butyl group to the entropy of the ideal gas is determined quantitatively here for the first time based on the calorimetric results over the temperature range 298.15 < (T/K) < 600. Comparisons with literature values are shown for all measured and derived properties, including entropies for the ideal gas derived from quantum chemical calculations.     

Low-temperature thermodynamic properties of Ir(C5H7O2)3: Connection of entropy with the molecule volume for tris-acetylacetonates of metals

The heat capacity of Ir(C₅H₇O₂)₃ has been measured by the adiabatic method within the temperature range (5 to 305) K. The thermodynamic functions (entropy, enthalpy, and reduced Gibbs free energy) at 298.15 K have been calculated using the obtained experimental heat capacity data. A connection has been found between the entropy and the volume of the elementary crystalline cell for β-acetylacetonates of some metals. The reasons for this interdependence are discussed. The values of entropies at T = 298.15 K have been calculated for all the metal acetylacetonates on which there are structural data.     

The standard thermodynamic functions of fullerene chloride,C60Cl30

The heat capacity of a crystal solvate of fullerene chloride, C₆₀Cl₃₀·0.09 Cl₂, was measured by vacuum adiabatic calorimetry in the temperature range from (25 to 371.5) K. The thermodynamic functions (changes of the enthalpy, entropy, and Gibbs free energy) of C₆₀Cl₃₀·0.09 Cl₂ have been derived. On the basis of obtained data and the enthalpy of formation of C₆₀Cl₃₀ determined before, the entropy and Gibbs free energy of formation of the fullerene chloride were calculated at T = 298.15 K.     

Thermodynamic properties of some cyclohexyl esters in the condensed state

The heat capacities and the enthalpies of phase transitions of cyclohexyl esters (formate, acetate, butyrate, and valerate) in the condensed state between T =  (5 and 320) K were measured in a vacuum adiabatic calorimeter. It was found that all liquid compounds were supercooled by cooling them fromT =  300 K at a rate of (0.02 to 0.03)K · s ^− 1and formed glasses. Crystalline phases were obtained for all esters and the residual entropies of glasses at T →  0 were evaluated. The glass transition temperatures and the heat capacity jumps accompanying the glass transitions, as well as the thermodynamic parameters of fusion of crystalline phases, were determined for all the esters. The molar thermodynamic functions of the investigated compounds in the crystalline, liquid, supercooled liquid, and glassy states were obtained. The regular changes of some thermodynamic properties in the series of cyclohexyl esters are discussed.     

Experimental and theoretical study of thermodynamic properties of levoglucosan

The heat capacity of levoglucosan was measured over the temperature range (5 to 370) K by adiabatic calorimetry. The temperatures and enthalpies of a solid-phase transition and fusion for the compound were found by DSC. The obtained results allowed us to calculate thermodynamic properties of crystalline levoglucosan in the temperature range (0 to 384) K. The enthalpy of sublimation for the low-temperature crystal phase was found from the temperature-dependent saturated vapor pressures determined by the Knudsen effusion method. The thermodynamic properties of gaseous levoglucosan were calculated by methods of statistical thermodynamics using the molecular parameters from quantum chemical calculations. The enthalpy of formation of the crystalline compound was found from the experiments in a combustion calorimeter. The gas-phase enthalpy of formation was also obtained at the G4 level of theory. The thermodynamic analysis of equilibria of levoglucosan formation from cellulose, starch, and glucose was conducted.     

Thermodynamic stability of AuSe at temperature from (400 to 700) K by a solid state galvanic cell

The numerical values on the standard thermodynamic functions of AuSe were determined by the electromotive force (EMF) method in a solid-state galvanic cell with a superionic conductor AgI as the solid electrolyte. According to the experimental data on the EMF vs. temperature, the analytical equations for Gibbs free energy, enthalpy and entropy were obtained for the single stable polymorphic form of AuSe. The temperature-dependent relationships of Gibbs free energy of formation of AuSe and the standard thermodynamic functions of compounds within the temperature range (400 to 700) K were also evaluated. No α–β transformation was identified in the gold saturation and β-form is a metastable modification of AuSe.     

Solution thermodynamics of pyrazinamide,isoniazid, and p-aminobenzoic acid in buffers and octanol

The solubility values of pyrazinamide, isoniazid, and p-aminobenzoic acid in buffers (рН 2.0 and 7.4) and octanol were measured in the temperature range of 293.15 to 313.15 K. The dissolution Gibbs energy, enthalpy, and entropy were calculated. The dissolving process was endothermic and enthalpy-determined. The activity coefficients of the compounds at infinite dilution were determined based on the solubility data and thermophysical parameters. A positive deviation from the ideality was observed in all the solutions. A common tendency of the solubility increase with a decrease in the activity coefficients at T = 298.15 K was revealed for the investigated solute-solvent systems. The excess thermodynamic solubility functions were calculated from the temperature dependences of the activity coefficients. The solvation processes were found to have a considerable influence on the solubility of the substances in solutions studied.     

Fluorene: An extended experimental thermodynamic study

This work reports new experimental thermodynamic results on fluorene. Vapor pressures of both crystalline and liquid phases were measured using a pressure gauge (capacitance diaphragm manometer) and Knudsen effusion methods over a wide temperature range (292.20 to 412.16) K yielding accurate determination of enthalpy and entropy of sublimation and of vaporization. The enthalpy of sublimation was also determined using Calvet microcalorimetry. The enthalpy of fusion was derived from vapor pressure results and from d.s.c. experiments. Static bomb calorimetry was used to determine the enthalpy of combustion of fluorene from which the standard enthalpy of formation in the crystalline phase was calculated. The enthalpy of formation in the gaseous phase was calculated combining the result derived for the crystalline phase with the enthalpy of sublimation.     

Thermophysical properties of aqueous solutions of the 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid

Thermophysical behavior of the binary system [water + 1-ethyl-3-methylimidazolium tricyanomethanide ionic liquid (IL)] was thoroughly characterized through systematic measurements of (vapor + liquid) equilibria (water activity a_w), mixing enthalpy, density, viscosity, and refractive index. The measurements were performed in the entire composition range and/or specifically in the highly dilute IL region, at T = 298.15 K or as a function of temperature in the range from (288.15 to 318.15) K. Effective experimental methods minimizing IL sample consumption, using flow arrangements, instrument couplings and high degree of automation were preferably employed. In particular, the a_w determination based on the chilled-mirror dew point technique and implemented by an AquaLab 4TE instrument was identified as a generally superior approach to study VLE of (water + IL) systems. Excess thermodynamic properties (Gibbs free energy, enthalpy, heat capacity, and volume) and property deviations from the linear mixing rule (viscosity, refractive index) were evaluated, Padé approximants being used to correlate adequately their complex composition dependences. The extensive a_w data were processed by a two-step procedure fitting first the temperature dependence at each isopleth and subsequently the composition dependence at each isotherm. Good estimates could be thus obtained for derivative thermal properties (enthalpy, heat capacity). Alternatively, the water activity and excess enthalpy data were correlated simultaneously by a NRTL-type model, providing their compact, thermodynamically consistent and adequate representation. Despite small absolute values of excess Gibbs free energy (G^E), the system is revealed to be highly nonideal, the small G^E resulting from close compensation of its large enthalpy and entropy contributions. Large endothermic effects and an enhanced increase of entropy upon mixing found for this system indicate relative weakness of interactions between unlike molecules and a massive structure breakage in the solution. Positive values of excess volume and negative values of viscosity and refractive index deviations found in the major part of the composition range corroborate this general energetic and structural pattern, although the situation appears to be more complicated in the highly dilute IL region, where these properties congruently exhibit a sign inversion.     

Heat capacity and thermodynamic properties of germanium disulfide at temperatures from T = (2 to 1240) K

The heat capacity of polycrystalline germanium disulfide α-GeS₂ has been measured by relaxation calorimetry, adiabatic calorimetry, DSC and heat flux calorimetry from T = (2 to 1240) K. Values of the molar heat capacity, standard molar entropy and standard molar enthalpy are 66.191 J · K^?1 · mol^?1, 87.935 J · K^?1 · mol^?1 and 12.642 kJ · mol^?1. The temperature of fusion and its enthalpy change are 1116 K and 23 kJ · mol^?1, respectively. The thermodynamic functions of α-GeS₂ were calculated over the range (0 ? T/K ? 1250).     

Thermodynamic study of phase transitions in methyl esters of ortho- meta- and para-aminobenzoic acids

A static method based on capacitance gauges was used to measure the vapor pressures of the condensed phases of the methyl esters of the three aminobenzoic acids. For methyl o-aminobenzoate the vapor pressures of the liquid phase were measured in the range (285.4 to 369.5) K. For the meta and para isomers vapor pressures of both crystalline and liquid phases were measured in the ranges (308.9 to 376.6) K, and (332.9 to 428.0) K, respectively. Vapor pressures of the latter compound were also measured using the Knudsen effusion method in the temperature range (319.1 to 341.2) K.From the dependence of the vapor pressures on the temperature, the standard molar enthalpies and entropies of sublimation and of vaporization were derived. Differential scanning calorimetry was used to measure the temperatures and molar enthalpies of fusion of the three isomers. The results enabled the estimation of the enthalpy of the intermolecular (N−H^…O) hydrogen bond in the crystalline methyl p-aminobenzoate. A correlation relating the temperature of fusion and the enthalpy and Gibbs energy of sublimation of benzene, methyl benzoates and benzoic acids was derived.     

Solid–liquid equilibrium and thermochemical studies of organic analogue of metal–nonmetal system: Succinonitrile–pentachloronitrobenzene

The phase diagram of an organic analogue of a metal–nonmetal system, involving succinonitrile–pentachloronitrobenzene, shows the formation of a eutectic and a monotectic. The two immiscible liquid phases are in equilibrium with a single liquid phase and the consolute temperature being 53.5 °C above the monotectic horizontal. The phase equilibrium study confirms the alloy composition of monotectic and eutectic at 0.150 and 0.985 mol fractions of succinonitrile, respectively. The solidification behaviour shows the validity of Hilling–Turnbull equation. The thermal properties such as heat of mixing, entropy of fusion, roughness parameter, interfacial energy, grain boundary energy and excess thermodynamic functions for parent components, monotectic and eutectic have been studied using their enthalpy of fusion values. The effects of solid–liquid interfacial energy on morphological change of monotectic have also been discussed. The microstructure of monotectic shows the lamellar growth along with droplets, however, eutectic infers the vertical growth of lamella.     

High-temperature calorimetry of zirconia: Heat capacity and thermodynamics of the monoclinic–tetragonal phase transition

The high-temperature heat capacity of zirconia was directly measured by differential scanning calorimetry between T = (1050 and 1700) K and derived from the heat content measured by transposed temperature drop calorimetry between T = (970 and 1770) K, including the monoclinic–tetragonal (m–t) phase transition region. The enthalpy and entropy of the m–t phase transition are (5.43 ± 0.31) kJ · mol⁻¹ and (3.69 ± 0.21) J · K⁻¹ · mol⁻¹, respectively. Values of thermodynamic functions are provided from room temperature to 2000 K.     

Synthesis,physical, and thermodynamic properties of 1-alkyl-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide ionic liquids

Synthesis of new ionic liquids (ILs) viz. 1-butyl-3-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide, [BCN³Py][NTf₂], 1-hexyl-3-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide, [HCN³Py][NTf₂], 1-hexyl-4-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide, [HCN⁴Py][NTf₂], and 1-octyl-3-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide, [OCN³Py][NTf₂] were performed. The specific basic characterization of new compounds by NMR spectra, elementary analysis, water content and glass transition temperature as well as melting temperature, enthalpy of fusion and decomposition of compounds TG/DTA determined by the differential scanning calorimetry, DSC is presented. The heat capacity was measured at three temperatures (298.15, 323.15, and 353.15) K and at pressure 0.1 MPa. The effect of temperature on the density and viscosity is reported over the temperature range from (293.15 to 363.15) K and at 0.1 MPa. The density and viscosity correlation for these systems was provided by an empirical polynomial. From the density–temperature dependence, the isothermal expansion coefficient (volume expansivity), α, was calculated. The surface tension of pure ionic liquids was measured at 0.1 MPa at five temperatures (298.15, 308.15, 318.15, 328.15, and 338.15) K. The surface thermodynamic functions such as surface entropy and enthalpy, critical temperatures according to the Eötvös and Guggenheim definition and the total surface energy of the ILs studied were derived from the temperature dependence of the surface tension values. The parachor and speed of sound for pure ionic liquids were described within a range of temperature from (298.15 to 338.15) K. A qualitative analysis on these quantities in terms of molecular interactions is reported.     

Solubility and solution thermodynamics of 2,3,4,5-tetrabromothiophene in (ethanol + tetrahydrofuran) binary solvent mixtures

The solubility of 2,3,4,5-tetrabromothiophene in (ethanol + tetrahydrofuran) binary solvent mixtures was measured within the temperature range from (278.15 to 322.15) K. The solubility increases with the rise of temperature, while it decreases with increasing ethanol content at constant temperature. The experimental data were fitted using the two variants of the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) equation and the Jouyban–Acree equation, respectively. All the three equations were proven to give good representations of the experimental values. Computational results showed that the variant two of CNIBS/R–K equation was superior to the other two equations. The thermodynamic properties of the solution process, including the Gibbs free energy, enthalpy, and entropy, were calculated by the van’t Hoff analysis. The values of both the enthalpy change and the standard molar Gibbs free energy change of solution were positive, which indicated that the process was endothermic.     

Vapour pressure of diethyl phthalate

Measurements of vapour pressure in the liquid phase and of enthalpy of vaporisation and results of calculation of ideal-gas properties for diethyl phthalate are reported. The method of comparative ebulliometry, the static method, and the Knudsen mass-loss effusion method were employed to determine the vapour pressure. A Calvet-type differential microcalorimeter was used to measure the enthalpy of vaporisation. Simultaneous correlation of vapour pressure, of enthalpy of vaporisation and of difference in heat capacities of ideal gas and liquid/solid phases was used to generate parameters of the Cox equation that cover both the (vapour + solid) equilibrium (approximate temperature range from 220 K to 270 K) and (vapour + liquid) equilibrium (from 270 K to 520 K). Vapour pressure and enthalpy of vaporisation derived from the fit are reported at the triple-point temperature T = 269.92 K (p = 0.0029 Pa, Δ_vapH_m = 85.10 kJ · mol⁻¹ ), at T = 298.15 K (p = 0.099 Pa, Δ_vapH_m = 82.09 kJ · mol⁻¹), and at the normal boiling temperature T = 570.50 K (Δ_vapH_m = 56.49 kJ · mol⁻¹). Measured vapour pressures and measured and calculated enthalpies of vaporisation are compared with literature data.     

Molar heat capacity and thermodynamic properties of 1-cyclohexene-1,2-dicarboxylic anhydride [C8H8O3]

The molar heat capacity C_p,m of 1-cyclohexene-1,2-dicarboxylic anhydride was measured in the temperature range from T=(80 to 360) K with a small sample automated adiabatic calorimeter. The melting point T_m, the molar enthalpy Δ_fusH_m and the entropy Δ_fusS_m of fusion for the compound were determined to be (343.46 ± 0.24) K, (11.88 ± 0.02) kJ · mol⁻¹ and (34.60 ± 0.06) J · K⁻¹ · mol⁻¹, respectively. The thermodynamic functions [H_(T)−H_(298.15)] and [S_(T)−S_(298.15)] were derived in the temperature range from T=(80 to 360) K with temperature interval of 5 K. The mass fraction purity of the sample used in the adiabatic calorimetric study was determined to be 0.9928 by using the fractional melting technique. The thermal stability of the compound was investigated by differential scanning calorimeter (DSC) and thermogravimetric (TG) technique, and the process of the mass-loss of the sample was due to the evaporation, instead of its thermal decomposition.