The vapor pressures of three 4-substituted acetanilide derivatives (namely, 4-ethoxyacetanilide, 4-hydroxyacetanilide and 4-bromoacetanilide) were measured above their liquids using the mass loss rates determined by thermogravimetry under both isothermal and nonisothermal diffusion-controlled conditions. The coefficient used to convert mass loss rates in vapor pressures showed a slight increase with increasing temperature. Therefore, the small deviations observed from the mean value enable the use of a single calibration value to be considered reasonable. From the temperature dependence of the vapor pressure estimated using a calibration constant for each technique the molar enthalpies of vaporization gH◦ (␣T␣) were determined, respectively, at the middle ⟨T⟩ of the respective temperaturel m intervals. The melting temperatures and the molar enthalpies of fusion of these compounds were measured by differential scanning calorimetry. Finally, the standard molar enthalpies of sublimation g H◦ (298.15K) were obtained at the reference temperature of 298.15K using the standard molar ␣␣ cr menthalpies of vaporization gl Hm◦ ( T ), the molar enthalpies of fusion, the heat capacity differences between gas and liquid and the heat capacity differences between gas and solid, gl Cp◦,m and gcrCp◦,m,respectively, both estimated by applying a group additivity procedure. Therefore, the averages of thestandard (p◦ = 0.1 MPa) molar enthalpies, entropies and Gibbs energies of sublimation at 298.15 K, havebeen derived: Compound 4-Ethoxyacetanilide 4-Hydroxyacetanilide 4-Bromoacetanilide 120 ± 3 138 ± 3 110 ± 4 232 ± 9 245 ± 9 204 ± 10 gcr Gm◦ (298.15 K) (kJ mol−1 ) 52 ± 5 65 ± 5 49 ± 6

Vapor pressures and standard molar enthalpies, entropies and Gibbs energies of sublimation of three 4-substituted acetanilide derivatives / VECCHIO CIPRIOTI, Stefano; Tomassetti, Mauro. - In: FLUID PHASE EQUILIBRIA. - ISSN 0378-3812. - ELETTRONICO. - 279:1(2009), pp. 64-72. [10.1016/j.fluid.2009.02.001]

Vapor pressures and standard molar enthalpies, entropies and Gibbs energies of sublimation of three 4-substituted acetanilide derivatives

VECCHIO CIPRIOTI, Stefano;TOMASSETTI, Mauro
2009

Abstract

The vapor pressures of three 4-substituted acetanilide derivatives (namely, 4-ethoxyacetanilide, 4-hydroxyacetanilide and 4-bromoacetanilide) were measured above their liquids using the mass loss rates determined by thermogravimetry under both isothermal and nonisothermal diffusion-controlled conditions. The coefficient used to convert mass loss rates in vapor pressures showed a slight increase with increasing temperature. Therefore, the small deviations observed from the mean value enable the use of a single calibration value to be considered reasonable. From the temperature dependence of the vapor pressure estimated using a calibration constant for each technique the molar enthalpies of vaporization gH◦ (␣T␣) were determined, respectively, at the middle ⟨T⟩ of the respective temperaturel m intervals. The melting temperatures and the molar enthalpies of fusion of these compounds were measured by differential scanning calorimetry. Finally, the standard molar enthalpies of sublimation g H◦ (298.15K) were obtained at the reference temperature of 298.15K using the standard molar ␣␣ cr menthalpies of vaporization gl Hm◦ ( T ), the molar enthalpies of fusion, the heat capacity differences between gas and liquid and the heat capacity differences between gas and solid, gl Cp◦,m and gcrCp◦,m,respectively, both estimated by applying a group additivity procedure. Therefore, the averages of thestandard (p◦ = 0.1 MPa) molar enthalpies, entropies and Gibbs energies of sublimation at 298.15 K, havebeen derived: Compound 4-Ethoxyacetanilide 4-Hydroxyacetanilide 4-Bromoacetanilide 120 ± 3 138 ± 3 110 ± 4 232 ± 9 245 ± 9 204 ± 10 gcr Gm◦ (298.15 K) (kJ mol−1 ) 52 ± 5 65 ± 5 49 ± 6
2009
4-bromoacetanilide; 4-bromoacetanilide.; 4-ethoxyacetanilide; 4-hydroxyacetanilide; enthalpies of sublimation; entropies of sublimation; standard gibbs energy of sublimation; vapor pressures
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Vapor pressures and standard molar enthalpies, entropies and Gibbs energies of sublimation of three 4-substituted acetanilide derivatives / VECCHIO CIPRIOTI, Stefano; Tomassetti, Mauro. - In: FLUID PHASE EQUILIBRIA. - ISSN 0378-3812. - ELETTRONICO. - 279:1(2009), pp. 64-72. [10.1016/j.fluid.2009.02.001]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/227989
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