Vapor pressures and vaporization enthalpies of 5-nonanone, linalool and 6-methyl-5-hepten-2-one. Data evaluation

© 2014 Elsevier B.V.. Vapor pressures and vaporization enthalpies for 5-nonanone, linalool and 6-methyl-5-hepten-2-one seem to be in disarray. Temperature dependences of vapor pressures for these pure compounds were measured by using the static and the transpiration techniques. Molar standard enthalpies of vaporization at the reference temperature were derived. Available literature data on vapor pressures and vaporization enthalpies were collected and analyzed. The consistent data set for each compound was evaluated. Reliable thermodynamic parameters of vaporization were derived and used to test some commonly used predicting procedures

Structure–property relationships in halogenbenzoic acids: Thermodynamics of sublimation, fusion, vaporization and solubility

© 2016 Elsevier LtdTemperature dependences of vapor pressures for 2-, 3-, and 4-bromobenzoic acid, as well as for five isomeric bromo-methylbenzoic acids were studied by the transpiration method. Melting temperatures and enthalpies of fusion for all isomeric bromo-methylbenzoic acids and 4-bromobenzoic acid were measured with a DSC. The molar enthalpies of sublimation and vaporization were derived. These data together with results available in the literature were collected and checked for internal consistency using a group-additivity procedure and results from X-ray structural diffraction studies. Specific (hydrogen bonding) interactions in the liquid and in the crystal phase of halogenbenzoic acids were quantified based on experimental values of vaporization and sublimation enthalpies. Structure-property correlations of solubilities of halogenobenzoic acids with sublimation pressures and sublimation enthalpies were developed and solubilities of bromo-benzoic acids were estimated. These new results resolve much of the ambiguity in the available thermochemical and solubility data on bromobenzoic acids. The approach based on structure property correlations can be applied for the assessment of water solubility of sparingly soluble drugs

Thermodynamic properties of glycerol: Experimental and theoretical study

© 2015 Elsevier B.V. Vapor pressures of highly pure glycerol were measured by the static and the transpiration methods in a broad temperature range. The standard molar enthalpy of vaporization of glycerol was derived from the vapor pressure temperature dependencies. Thermodynamic data on glycerol available in the literature were collected, evaluated, and combined with own experimental results. We recommend the set of vaporization and formation enthalpies for glycerol at 298.15K (in kJmol-1): δfHm° (g)=-(578.8±0.6), δfHm° (l)=-(669.3±0.5), and δlgHm° =(90.5±0.3) as the reliable benchmark properties for further thermochemical calculations. Quantum-chemical calculations of the gas phase molar enthalpy of formation of glycerol have been performed using the G4 method and results were in agreement with the recommended experimental data. The standard molar entropy of formation and the standard molar Gibbs function of formation of glycerol were estimated

Thermochemistry of ammonium based ionic liquids: Thiocyanates - Experiments and computations

© Springer Science+Business Media New York 2015. Abstract Molar enthalpies of solution of tetra-n-butylammonium thiocyanate [N(Bu)4][SCN] and tetra-n-pentylammonium thiocyanate [N(Pe)4][SCN] in water were measured by using solution calorimetry. The enthalpy of combustion of [N(Bu)4][SCN] was measured by using rotation bomb combustion calorimetry and the enthalpy of formation of this ionic liquids was derived. The thermal behavior of [N(Bu)4][SCN] was studied using differential scanning calorimetry. Quantum-chemical calculations of the molar enthalpy of formation in the gaseous phase have been performed for the series [N(R)4][SCN] with RA =(Me, Et, n-Bu, and n-Pe) using the G3MP2 level of theory. Experimental and calculated values of the enthalpies of formation are in agreement within the boundaries of the experimental uncertainties

Alkyl-imidazolium tetrafluoroborates: Vapor pressure, thermodynamics of vaporization, and enthalpies of formation

© 2017 Elsevier B.V. The absolute vapor pressures for the series of [C n mim][BF 4 ] ionic liquids with (n = 2, 4, 6, 8, and 10) were measured over the temperature range 404–457 K by using the quartz-crystal microbalance. An absence of possible thermal decomposition was monitored by the ATR-IR spectroscopy. The molar enthalpies of vaporization of ionic liquids under study were derived from vapor pressure temperature dependences and adjusted to the reference temperature 298.15 K. The liquid phase molar enthalpy of formation of [C 2 mim][BF 4 ] was derived from the solution calorimetry and combined with its molar vaporization enthalpy to get the first experimental gas-phase molar enthalpy of formation of the [BF 4 ] − containing ionic liquid. A computational approach based on the DLPNO-CCSD(T) method was used to calculate the theoretical gas-phase molar enthalpy of formation of [C 2 mim][BF 4 ]. The theoretical and experimental results were found to be in agreement within the combined uncertainties, providing the mutual validation of experimental and computational procedures used in the current study

Benchmark Thermochemistry of N-Methylaniline

© 2015 American Chemical Society. In this work, the standard molar enthalpy of formation in the gaseous state of highly pure N-methylaniline, δfHm° (g, 298.15 K) = 90.9 ± 2.1 kJ·mol-1, has been obtained from the calorimetrically measured energy of combustion converted into the enthalpy of formation, δfHm° (liq, 298.15 K) = 35.9 ± 2.1 kJ·mol-1, and from the molar enthalpy of vaporization, δlgHm = 55.0 ± 0.2 kJ·mol-1, derived from vapor pressure measurements by transpiration method. The enthalpy of formation of N-methylaniline calculated using the quantum chemical G4 method was in excellent agreement with the experimental value. The frequencies of normal vibrations were obtained from the experimental and calculated spectra. Thermodynamic properties of N-methylaniline in the ideal gas state were calculated from molecular and spectral data in the temperature range 100-1500 K

Thermochemistry of Pyridinium Based Ionic Liquids with Tetrafluoroborate Anion

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, WeinheimEnthalpies of vaporization of five pyridinium based ionic liquids (ILs): 1-R-pyridinium (with R = ethyl, butyl-, and hexyl), 1-butyl-3-methyl-pyridinium, and 1-butyl-4-methyl-pyridinium with tetrafluoroborate anion were studied using Quartz Crystal Microbalance (QCM). Enthalpies of solution of these ionic liquids were measured by high-precision solution calorimetry. Gas-phase enthalpies of formation of ILs were calculated by using the high-level quantum-chemical method G3MP2. From combination of experimental and theoretical results, enthalpies of formation of aqueous pyridinium based cations were derived for the first time

Thermodynamic properties of isomeric iso-butoxybenzoic acids: Experimental and theoretical study

© 2015 Elsevier B.V. All rights reserved. Standard (p° = 0.1 MPa) molar enthalpies of formation at the temperature T = 298.15 K of the 2-, 3-, and 4-iso-butoxybenzoic acids were measured using the combustion calorimetry. Standard molar enthalpies of vaporization and sublimation were derived from the vapor pressure temperature dependencies measured by the transpiration method. Molar enthalpies of the solid state phase transitions were measured by the DSC. Thermodynamic data on alkoxy substituted benzoic acids available in the literature were collected and combined with own experimental results. This data set on alkoxybenzoic acids was evaluated by using quantum-chemical and group-additivity methods

Structure-property relationships in ionic liquids: Chain length dependence of the vaporization enthalpies of imidazolium-based ionic liquids with fluorinated substituents

© 2015 Elsevier B.V. Molar vaporization enthalpies of fluoroalkyl-substituted imidazolium-based ionic liquids were derived from two concurring quartz crystal microbalance (QCM) and thermogravimetry (TGA) methods. For comparison, enthalpies of vaporization measured at elevated temperatures have been adjusted to the reference temperature 298K and tested for consistency. It was found that vaporization enthalpies of fluorine substituted families are significantly higher compared to the analogous ILs with the alkyl-substituted cation. This is in agreement to molecular solvents, where fluorination typically increases vaporization enthalpy relative to hydrocarbon analogues. A useful group contribution for the incremental CF2 fragment in the alkyl chain was recommended for the quick estimation of vaporization enthalpies of various substituted IL cations (e.g., imidazolium, ammonium, pyridinium, etc.)

Thermochemistry of halogenobenzoic acids as an access to PC-SAFT solubility modeling

© 2015 Elsevier B.V. Absolute vapor pressures and molar sublimation enthalpies of 2-, 3-, and 4-monohalogenobenzoic acids (halogen = fluorine and iodine) were derived from transpiration measurements. Molar enthalpies of fusion were measured by DSC. Thermochemical data available in the literature were collected, evaluated, and combined with own experimental results in order to recommend sets of sublimation and fusion enthalpies. Further, the recommended data were used to estimate PC-SAFT pure-component parameters. These parameters were applied to predict the solubility of the monohalogenobenzoic acids in water at 298.15 K, yielding satisfying prediction results. This approach proved the capability of PC-SAFT to predict solid-liquid phase equilibria if precise data on sublimation pressures and fusion properties is available