M. Monte, A. R. Almeida, M. Matos
Jan 14, 2010
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Journal
Journal of Chemical & Engineering Data
Abstract
The Knudsen mass-loss effusion technique was used to measure the vapor pressures at different temperatures of the following aminomethoxybenzoic acids: 2-amino-3-methoxybenzoic acid, between (349.12 and 369.18) K; 2-amino-5-methoxybenzoic acid, between (353.13 and 375.17) K; 3-amino-4-methoxybenzoic acid, between (379.67 and 399.18) K; 3-amino-5-methoxybenzoic acid, between (380.16 and 400.18) K; and 4-amino-3-methoxybenzoic acid, between (373.14 and 395.17) K. From the temperature dependences of the vapor pressure of the crystalline compounds, the standard (po = 105 Pa) molar enthalpies and Gibbs energies of sublimation, at T = 298.15 K, were derived. The results allowed the estimation of these two thermodynamic properties for two isomers not studied in this work—2-amino-6-methoxybenzoic acid and 3-amino-2-methoxybenzoic acid. Differential scanning calorimetry was used to measure the temperature and molar enthalpy of fusion of the studied isomers.