ABSTRACT

The sublimation enthalpies of some hydroxyflavones and one amineflavone were determined with a thermogravimetric device under isothermal conditions. These enthalpies were obtained by measuring the rate of mass loss as a function of temperature. In this methodology, the Clausius-Clapeyron and Langmuir equations were used. The diffusional effect of the gas-phase was included in the Langmuir equation. In order to test and validate the experimental methodology, the sublimation enthalpy of three standard materials: anthracene, pyrene and benzoic acid were determined. The values obtained are in agreement with the data reported and recommended in the literature. Low uncertainties were obtained in all thermogravimetric measurements. Additionally, by differential scanning calorimetry, the molar fraction, temperature and enthalpy of fusion, and heat capacity of the solid phase were determined for all the compounds studied. The heat capacities of the gas phase were estimated using computational methods. Isothermal thermogravimetry was applied to study a family of flavones.

Compounds

#	Formula	Name
1	C16H10	pyrene
2	C14H10	anthracene
3	C7H6O2	benzoic acid
4	C15H10O3	3-hydroxyflavone
5	C15H10O3	5-hydroxyflavone
6	C15H10O3	6-hydroxyflavone
7	C15H10O3	7-hydroxyflavone
8	C15H11NO2	6-aminoflavone

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Constraint	Phase	Method	#Points
POMD	1	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	1	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	1	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	25
POMD	1	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1
POMD	2	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	2	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	29
POMD	2	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1
POMD	3	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	3	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	3	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	20
POMD	3	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1
POMD	4	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	4	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	4	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	29
POMD	4	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1
POMD	5	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	5	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	5	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	27
POMD	5	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1
POMD	6	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	6	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	6	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	42
POMD	6	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1
POMD	7	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	7	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	7	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	42
POMD	7	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1
POMD	8	Normal melting temperature, K ; Crystal			Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	8	Molar enthalpy of transition or fusion, kJ/mol ; Crystal			Crystal Liquid Air at 1 atmosphere	DSC	1
POMD	8	Molar heat capacity at constant pressure, J/K/mol ; Crystal	Temperature, K; Crystal	Pressure, kPa; Crystal	Crystal	DSC	34
POMD	8	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal		Crystal Gas	Derived by Second law	1

Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

Isothermal Thermogravimetric Study for Determining Sublimation Enthalpies of Some Hydroxyflavones

Flores, Henoc, Ramos, Fernando, Camarillo, Elsa A., Santiago, Omar, Perdomo, Gaston, Notario, Rafael, Cabrera, Sandra

ABSTRACT