Authors:M. Crespi, H. Zorel, C. Ribeiro, A. Costalonga, and C. Torres
5-Nitro-8-hydroxyquinoline (B) and 5,7-dinitro-8-hydroxyquinoline (C) were obtained from nitration of 8-hydroxyquinoline (A)
and purified in acetone medium and under heating in which the formation of (B) or (C) depends on the amount of HNO3 added. TG curves present mass loss in only one step before and after the melting point (Tm =76C (A) and 180C (B)) in different proportions as a function of the heating rate, characterising the sublimation and the
volatilisation processes, respectively. The thermal stability of the compounds follow the order: A (77C)<B (121C)<C (222C).
Kinetic parameters through TG curves, dynamic process, using heating rates of 1, 2.5, 5, 10 and 20C minȡ1 , enabled to obtain the following increasing order to the activation energy values of the compounds: 80.4 (A), 102.0 (B)
and 153.9 kJ mol−1 (C). Other kinetic parameters as pre-exponential and half-lifetime were also estimated.
There is considerable interest in performing volatilisation and evaporation measurements by thermogravimetry. A quick and
simple method for determining vapour pressure using a conventional thermobalance and standard sample holders has been developed.
These yield meaningful thermodynamic parameters such as the enthalpies of sublimation and vaporisation. Under favourable conditions
the melting temperature and enthalpy of fusion of such compounds can be obtained. This technique has been used for the study
of dyes, UV absorbers and plasticisers. The use of modulated- temperature programs for such work is also described.
Authors:P. Storoniak, K. Krzymiński, A. Boużyk, E. Koval'chuk, and J. Błażejowski
The enthalpies and temperatures of melting and sublimation of acridin-9(10H)-one, 10-methylacridin-9(10H)-one, 2,10-dimethylacridin-9(10H)-one,
10-methyl-2-nitroacridin-9(10H)-one, 10-ethylacridin-9(10H)-one and 10-phenylacridin-9(10H)-one were measured by DSC. Enthalpies
and temperatures of volatilisation were also obtained by fitting TG curves to the Clausius-Clapeyron relationship. Complementary
investigations for anthracene showed the extent to which the thermodynamic characteristics thus obtained compare with those
determined by means of other techniques. For compounds whose crystal structures are known, experimental enthalpies of sublimation
correspond reasonably well to crystal lattice enthalpies predicted theoretically as the sum of electrostatic, dispersive and
repulsive interactions. Analysis of crystal lattice enthalpy contributions indicates that dispersive interactions always predominate.
Interactions are enhanced in acridin-9(10H)-one where intermolecular hydrogen bonds occur: this is reflected in the relatively
high enthalpy of sublimation.
Authors:E. Fedoseev, M. Aizenberg, S. Travnikov, A. Davydov, and B. Myasoedov
Volatile einsteinium hexafluoroacetylacetonate complexes have been syntehsized. Their sublimation and thermochromatographic behaviour has been studied in the presence of -diketone vapours. Interaction of einsteinium di-and trichloride with hexafluoracetylacetone vapours is discussed.
E37 on Thermal Measurements published a new test method 'Standard Test
Method for Volatility Rate by Thermogravimetry' in June 1999 with the
designation E 2008. This approach to assessing volatility utilizes an extension
of the pinhole technology previously employed by E37 for vapor pressure determinations
using differential scanning calorimetry (ASTM E 1782). After publication of
the test method E 2008, an Interlaboratory Study was undertaken to develop
a 'Precision and Bias' statement to be assigned with the test
method. This paper provides some background data that supports the claim that
E 2008 is generally insensitive to experimental conditions other than temperature.
The Interlaboratory Study showing the statistical review is also discussed.
When annealing the evaporation residue formed by evaporating a solution containing ruthenium, phosphates and nitrates, ruthenium
volatilizes. The amount of volatilized ruthenium (both106Ru traces and milligram amuonts of Ru) depends on the solution composition before evaporation and on the temperature and time
of annealing. Volatility occurs at a temperature as low as 300°C. We suppose that the volatility is due to thermal decomposition
of the ruthenium compounds with phosphates. The released atoms of ruthenium are oxidized by the decomposition products of
the nitrate. The formation of complex compounds of ruthenium with phosphates during the evaporation of the solution follows
from the data of elemental and spectral analysis and ion exchange chromatography.