The measurement of densities, specific viscosities of substituted thiopyrimidine drugs of different concentration in the range (1x10-2 M to 6x10-4 M) in 70% (DMF+water) solvent at 303K are reported. The experimental data shows, the effect of concentration of solute on viscosity in DMF-water mixtures which gives idea about the molecular interactions present in different solutions. Appreciable molecular interactions have been observed between the substituted thiopyrimidine and binary mixture. The themodynamic properties such as free energy change(ΔG), enthalpy change(ΔH) and entropy change (ΔS) of substituted thiopyrimidine drugs have been investigated in 70% (DMF+water) mixture at different temperature such as 308K, 313K and 318K. The experimental data gives the idea about effect of temperature on the molecular interaction and structural changes in solute.
