ABSTRACT

The standard (po = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, at the reference temperature of 298.15 K, of 2-amino-4-methylpyrimidine ((98.1+-1.6) kJ.mol-1), 2-amino-4,6-dimethylpyrimidine ((55.9 +-1.8) kJ.mol-1) and 4-amino-2,6-dimethylpyrimidine ((60.1+-1.8) kJ.mol-1) were calculated from the enthalpies of formation, in the crystalline phase, and enthalpies of sublimation, derived, respectively, from static bomb combustion calorimetry and Knudsen effusion technique results. In order to quantify the resonance effects arising from the substitution on the pyrimidine ring, hypothetical isodesmic reactions were used to analyze the experimental gaseous-phase enthalpies of formation . The aromaticity of benzene, pyridine, pyrimidine and the substituted pyrimidines was investigated in terms of magnetic (NICS), geometric (HOMA), electronic (Shannon aromaticity, QTAIMs ring critical point properties and HOMO LUMO gap), reactive (hardness),vibrational (Kekule mode) and spectroscopic (UV-Vis) properties.

Compounds

#	Formula	Name
1	CO2	carbon dioxide
2	N2	nitrogen
3	H2O	water
4	O2	oxygen
5	C5H7N3	2-amino-4-methylpyrimidine
6	C6H9N3	2-amino-4,6-dimethylpyrimidine
7	C6H9N3	4-amino-2,6-dimethylpyrimidine

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	Mass density, kg/m3 ; Crystal	Temperature, K; Crystal Pressure, kPa; Crystal	Crystal	from the mass and dimensions of a pellet of the compound made in vacuum	1
POMD	5	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	37
POMD	6	Mass density, kg/m3 ; Crystal	Temperature, K; Crystal Pressure, kPa; Crystal	Crystal	from the mass and dimensions of a pellet of the compound made in vacuum	1
POMD	6	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	35
POMD	7	Mass density, kg/m3 ; Crystal	Temperature, K; Crystal Pressure, kPa; Crystal	Crystal	from the mass and dimensions of a pellet of the compound made in vacuum	1
POMD	7	Vapor or sublimation pressure, kPa ; Crystal	Temperature, K; Crystal	Crystal Gas	Calculated from knudsen effusion weight loss	43
RXND	5 1 2 3 4	Specific internal energy of reaction at constant volume, J/g			Static bomb calorimetry	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

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Energetics of aminomethylpyrimidines: An examination of the aromaticity of nitrogen heteromonocyclic derivatives

Galvao, T. L. P.[Tiago L.P.], Ribeiro da Silva, M. D. M. C.[Maria D. M. C.], Ribeiro da Silva, M. A. V.[Manuel A. V.]

ABSTRACT