Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Experimental study on the thermochemistry of 2-thiouracil, 5-methyl-2-thiouracil and 6-methyl-2-thiouracil

Ribeiro da Silva, M. A. V.[Manuel A. V.], Amaral, L. M. P. F.[Luisa M. P. F.], Szterner, P.[Piotr]
J. Chem. Thermodyn. 2013, 57, 380-386
ABSTRACT
The standard (p = 0.1 MPa) molar enthalpies of combustion, DcH0 m, of three crystalline compounds: 2-thiouracil, 5-methyl-2-thiouracil and 6-methyl-2-thiouracil, were determined, at the temperature of 298.15 K, using a rotating bomb combustion calorimeter. For these compounds, the vapour pressure as a function of temperature was measured by the Knudsen effusion technique and the standard molar enthalpies of sublimation, Dg crH0 m, at T = 298.15 K, were derived by the Clausius Clapeyron equation. These values were used to derive the standard molar enthalpies of formation of the investigated compounds in their condensed and gaseous phases, respectively. The derived standard molar enthalpies of formation in the gaseous state are analysed in the terms of structural enthalpic increments.
Compounds
# Formula Name
1 H2O4S sulfuric acid
2 CO2 carbon dioxide
3 N2 nitrogen
4 H2O water
5 O2 oxygen
6 C4H4N2OS 2-thiouracil
7 C5H6N2OS 5-methyl-2-thiouracil
8 C5H6N2OS 6-methyl-2-thiouracil
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
  • 6
  • Vapor or sublimation pressure, kPa ; Crystal
  • Temperature, K; Crystal
  • Crystal
  • Gas
  • Calculated from knudsen effusion weight loss
  • 36
  • POMD
  • 7
  • Vapor or sublimation pressure, kPa ; Crystal
  • Temperature, K; Crystal
  • Crystal
  • Gas
  • Calculated from knudsen effusion weight loss
  • 31
  • POMD
  • 8
  • Vapor or sublimation pressure, kPa ; Crystal
  • Temperature, K; Crystal
  • Crystal
  • Gas
  • Calculated from knudsen effusion weight loss
  • 56
  • RXND
  • 6
  • 1
  • 2
  • 3
  • 4
  • 5
  • Specific internal energy of reaction at constant volume, J/g
  • Rotating bomb calorimetry
  • 1
  • RXND
  • 7
  • 1
  • 2
  • 3
  • 4
  • 5
  • Specific internal energy of reaction at constant volume, J/g
  • Rotating bomb calorimetry
  • 1
  • RXND
  • 8
  • 1
  • 2
  • 3
  • 4
  • 5
  • Specific internal energy of reaction at constant volume, J/g
  • Rotating bomb calorimetry
  • 1