A new pressure DSC module (Mettler DSC27HP) and its abilities for vapor pressure determination in the range of subambient
pressure to 7 MPa are presented. To compare the new to an established method, vapor pressures of caffeine, naphthalene and
o-phenacetin have been determined both by pressure DSC and the Knudsen effusion cell method. These results, including the
derived heats of evaporation and heats of sublimation, are compared to literature values.
Authors:A. Bessonov, N. Morozova, P. Semyannikov, S. Trubin, N. Gelfond, and I. Igumenov
The thermal properties of dimethylgold(III) carboxylates of general formula [(CH3)2Au(OOCR)]2 (R=methyl (1), tert-buthyl (2), trifluoromethyl (3), or phenyl (4)) in solid state have been investigated by the thermogravimetric analysis. The temperature dependences of saturated vapour
pressure of complexes have been studied by the Knudsen effusion method with mass spectrometric indication. The thermodynamic
parameters ΔsubHT0 and ΔsubST0 of the sublimation processes have been calculated. Thermal decomposition of the vapour of complexes 1 and 2 has been studied by means of high temperature mass spectrometry in vacuum, and by-products of decomposition have been determined.
Authors:Manuel Monte, Luís Santos, José Fonseca, and Carlos Sousa
The vapour pressures of six para-substituted benzoic acids were measured using the Knudsen effusion method within the pressure range (0.1–1 Pa) in the following
temperature intervals: 4-hydroxybenzoic acid (365.09–387.28) K; 4-cyanobenzoic acid (355.14–373.28) K; 4-(methylamino)benzoic
acid (359.12–381.29) K; 4-(dimethylamino)benzoic acid (369.29–391.01) K; 4-(acetylamino)benzoic acid (423.10–443.12) K; 4-acetoxybenzoic
acid (351.28–373.27) K. From the temperature dependence of the vapour pressure, the standard molar enthalpy, entropy and Gibbs
energy of sublimation, at the temperature 298.15 K, were derived for each of the studied compounds using estimated values
of the heat capacity differences between the gaseous and the crystalline phases. Equations for estimating the vapour pressure
of para substituted benzoic acids at the temperature of 298.15 K are proposed.
Authors:Ricardo Picciochi, Hermínio Diogo, and Manuel Minas da Piedade
Combustion calorimetry, Calvet-drop sublimation calorimetry, and the Knudsen effusion method were used to determine the standard
(po = 0.1 MPa) molar enthalpies of formation of monoclinic (form I) and gaseous paracetamol, at T = 298.15 K:
were used to assess the predictions of the B3LYP/cc-pVTZ and CBS-QB3 methods for the enthalpy of a isodesmic and isogyric
reaction involving those species. This test supported the reliability of the theoretical methods, and indicated a good thermodynamic
consistency between the
is in a very good agreement with the reported results using the most sensitive techniques used in measuring sublimation rate of TNT: QCM and Knudseneffusionmethod 97 ± 7 and 103 kJ/mol, respectively [ 4 , 18 ]. However, a larger value of 131 kJ
Goldfarb , JL , Suuberg , EM 2008 Vapor pressures and enthalpies of sublimation of ten polycyclic aromatic hydrocarbons determined via the Knudseneffusionmethod . J Chem Eng Data 53 : 670 – 676 10.1021/je7005133