ABSTRACT

In the present work the energetic properties of phthalide and phthalic anhydride are assessed experimental and computationally allowing to calculate the standard molar enthalpy of formation, in the gaseous phase, of each compound. These results enabled to analyze and interpret the enthalpic and structural molecular effects of one and two ketone groups in the main structure of phthalan. The high-temperature Calvet microcalorimetry and the static bomb combustion calorimetry were used to measure, respectively, the enthalpy of sublimation and the massic energy of combustion of the two compounds. These data were combined to derive the standard molar enthalpy of formation, in the gaseous phase, of phthalide and phthalic anhydride. The gas-phase enthalpies of formation of phthalide and phthalic anhydride compounds were estimated using the composite G3(MP2)//B3LYP approach together with adequate gas-phase working reactions. The computational study was also extended to phthalan and the reliability of the value obtained for the correspondent gas-phase enthalpy of formation, when compared with the experimental value reported in the literature, contributes to validate the computational methodology used. The good agreement verified between computational and experimental results for the other two phthalan derivatives studied gave us confidence to estimate the gas-phase enthalpy of formation of the 2,5-dihydrofuran that was not studied experimentally. Complementary, natural bond orbital (NBO) calculations were also performed, allowing an advance on the analysis of the structural and reactivity characteristics of this type of compounds.

Compounds

#	Formula	Name
1	CO2	carbon dioxide
2	H2O	water
3	O2	oxygen
4	C8H6O2	1(3H)-isobenzofuranone
5	C8H4O3	isobenzofuran-1,3-dione

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	Phase	Method	#Points
POMD	4	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Static calorimetry	1
POMD	4	Molar enthalpy, kJ/mol ; Gas	Temperature, K; Gas	Gas Crystal	Drop calorimetry	1
POMD	5	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Static calorimetry	1
POMD	5	Molar enthalpy, kJ/mol ; Gas	Temperature, K; Gas	Gas Crystal	Drop calorimetry	1
RXND	4 1 2 3	Specific internal energy of reaction at constant volume, J/g			Static bomb calorimetry	1
RXND	5 1 2 3	Specific internal energy of reaction at constant volume, J/g			Static bomb calorimetry	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

The effect of ketone groups on the energetic properties of phthalan derivatives

Freitas, V. L. S.[Vera L. S.], Santos, C. P. F.[Claudia P. F.], Ribeiro da Silva, M. D. M. C.[Maria D. M. C.], Ribeiro da Silva, M. A. V.[Manuel A. V.]

ABSTRACT