ABSTRACT

The standard (p = 0.1 MPa) molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids were derived from their standard molar energies of combustion, in oxygen, at T = 298.15 K, measured by static bomb combustion calorimetry. The Calvet high temperature vacuum sublimation technique was used to measure the enthalpies of sublimation of 2- and 3-cyanobenzoic acids. The standard molar enthalpies of formation of the three compounds, in the gaseous phase, at T = 298.15 K, have been derived from the corresponding standard molar enthalpies of formation in the condensed phase and standard molar enthalpies for phase transition. The results obtained are (150.7 +- 2.0) kJ mol 1, (153.6 +- 1.7) kJ mol 1 and (157.1 +- 1.4) kJ mol 1 for 2-cyano, 3-cyano and 4-cyanobenzoic acids, respectively. Standard molar enthalpies of formation were also estimated by employing two different methodologies: one based on the Cox scheme and the other one based on several different computational approaches. The calculated values show a good agreement with the experimental values obtained in this work.

Compounds

#	Formula	Name
1	CO2	carbon dioxide
2	N2	nitrogen
3	H2O	water
4	O2	oxygen
5	C8H5NO2	2-cyanobenzoic acid
6	C8H5NO2	3-cyanobenzoic acid
7	C8H5NO2	4-cyanobenzoic acid

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	5	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	DTA	1
POMD	5	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Vacuum drop calorimetry	1
POMD	5	Molar enthalpy, kJ/mol ; Gas	Temperature, K; Gas Pressure, kPa; Gas	Gas	vacuum sublimation	1
POMD	6	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	stuart scientific smp2 calibrated apparatus	1
POMD	6	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Vacuum drop calorimetry	1
POMD	7	Normal melting temperature, K ; Crystal		Crystal Liquid Air at 1 atmosphere	stuart scientific smp2 calibrated apparatus	1
POMD	7	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Unpublished results by the authors	1
POMD	7	Molar enthalpy, kJ/mol ; Gas	Temperature, K; Gas Pressure, kPa; Gas	Gas	vacuum sublimation	1
RXND	6 1 2 3 4	Specific internal energy of reaction at constant volume, J/g			Static bomb calorimetry	1
RXND	7 1 2 3 4	Specific internal energy of reaction at constant volume, J/g			Static bomb calorimetry	1
RXND	5 1 2 3 4	Specific internal energy of reaction at constant volume, J/g			Static bomb calorimetry	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Standard molar enthalpies of formation of 2-, 3- and 4-cyanobenzoic acids

Ribeiro da Silva, M. A. V.[Manuel A. V.], Amaral, L. M. P. F.[Luisa M. P. F.], Boaventura, C. R. P.[Cristina R.P.], Gomes, J. R. B.[Jose R.B.]

ABSTRACT