Low-temperature heat capacity and thermodynamic properties of 2-amino-4,6-dimethoxypyrimidine

The low-temperature heat capacities of 2-amino-4, 6-dimethoxypyrimidine ( C6H9N3O2) were precisely measured by an automated adiabatic calorimeter in the temperature range of 78 to 394 K. The sample was observed to melt at (370.97 +/- 0.02) K. On the basis of the heat-capacity measurements, the molar enthalpy and entropy of the phase transition as well as chemical purity of the substance were determined to be (29853. 91 +/- 9. 25) J (.) mol(-1), (80.45 +/- 0.03) J (.) mol(-1) (.) K-1 and 99.84%, respectively. The thermodynamic function of the compound were derived and reported at an interval of 5 K. The, further research of the melting process for this compound has been carried out by means of DSC technique. The result was in agreement with that. obtained from the measurements of heat capacities.