ABSTRACT

Accurate values of standard molar enthalpies of formation in condensed phases can be obtained by combining high-level quantum chemistry calculations of gas-phase enthalpies of formation with experimentally determined enthalpies of sublimation or vapourization. The procedure is illustrated for catechol, resorcinol, and hydroquinone. Using W1-F12, the gas-phase enthalpies of formation of these compounds at T = 298.15 K were computed as ( 270.6, 269.4, and 261.0) kJ/mol, respectively, with an uncertainty of 0.4 kJ/mol. Using well characterised solid samples, the enthalpies of sublimation were determined with a Calvet microcalorimeter, leading to the following values at T = 298.15 K: (88.3 +- 0.3) kJ/mol, (99.7 +- 0.4) kJ/mol, and (102.0 +- 0.9) kJ/mol, respectively. It is shown that these results are consistent with the crystalline structures of the compounds.

Compounds

#	Formula	Name
1	C6H6O2	1,2-benzenediol
2	C6H6O2	1,3-benzenediol
3	C6H6O2	1,4-benzenediol

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	1	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	1	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Static calorimetry	1
POMD	2	Normal melting temperature, K ; Crystal 1		Crystal 1 Liquid Air at 1 atmosphere	DTA	1
POMD	2	Triple point temperature, K ; Crystal 2		Crystal 2 Crystal 1 Air at 1 atmosphere	DTA	1
POMD	2	Molar enthalpy of transition or fusion, kJ/mol ; Crystal 2		Crystal 2 Crystal 1 Air at 1 atmosphere	DSC	1
POMD	2	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal 2	Temperature, K; Crystal 2	Crystal 2 Gas	Static calorimetry	1
POMD	3	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	3	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Static calorimetry	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Enthalpies of formation of dihydroxybenzenes revisited: Combining experimental and high-level ab initio data

Goncalves, E. M.[Elsa M.], Agapito, F.[Filipe], Almeida, T. S.[Tania S.], Martinho Simoes, J. A.[Jose A.]

ABSTRACT