The standard (p? = 0.1 MPa) molar enthalpy of formation for crystalline 2,3-dihydroxypyridine was measured, at T = 298.15 K, by static bomb calorimetry and the standard molar enthalpy of sublimation, at T = 298.15 K, was obtained using Calvet microcalorimetry. These values were used to derive the standard molar enthalpy of formation of 2,3-dihydroxypyridine in gaseous phase, at T = 298.15 K, (263.9 +- 4.6) kJ Ae mol?1. Additionally, high-level density functional theory calculations using the B3LYP hybrid exchange-correlation energy functional with extended basis sets have been performed for all dihydroxypyridine isomers to determine the thermochemical order of stability of these systems. The agreement between experiment and theory for the 2,3-dihydroxypyridine isomer gives confidence to the estimates of the enthalpies of formation concerning the other five isomers. It is found that the enthalpic increment for the dihydroxy substitution of pyridine is equal to the sum of the respective enthalpic increment of the monosubstituted pyridines.
Compounds
#
Formula
Name
1
CO2
carbon dioxide
2
N2
nitrogen
3
H2O
water
4
O2
oxygen
5
C5H5NO2
2,3-dihydroxypyridine
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
5
Mass density, kg/m3 ; Crystal
Temperature, K; Crystal
Pressure, kPa; Crystal
Crystal
mass and volume measurments
1
POMD
5
Molar enthalpy, kJ/mol ; Gas
Temperature, K; Gas
Pressure, kPa; Gas
Gas
"vacuum sublimation" drop microcalorimetric method
1
RXND
5
1
2
3
4
Specific internal energy of reaction at constant volume, J/g