Thermochemistry of uracil and thymine revisited

Abstract

© 2015 Published by Elsevier Ltd. Thermochemical properties of uracil and thymine have been evaluated using additional experiments. Standard (p⁰ = 0.1 MPa) molar enthalpies of formation in the gas phase at T = 298.15 K for uracil -(298.1 ± 0.6) and for thymine -(337.6 ± 0.9) kJ · mol^-1 have been derived from energies of combustion measured by static bomb combustion calorimetry and molar enthalpies of sublimation determined using the transpiration method. The G3 and G4 quantum-chemical methods were used for calculations of theoretical gaseous enthalpies of formation being in very good agreement with the re-measured experimental values.