Temperature-dependent enthalpy parameters of the molecular interaction for urea and tetramethylurea as solutes in formamide, ethylene glycol and water

Abstract

Enthalpies of dilution of urea (U) solutions in formamide (FA), ethylene glycol (EG) and water were measured calorimetrically in the temperature range between (288.15 and 318.15) K. Based on the results obtained, the enthalpy-homotactic coefficients of pairwise (h22) and triplet (h222) interactions between the solvated U molecules were computed and compared with the similar data for the respective solutions of tetramethylurea (TMU). An analysis was done of how temperature influences the solvophilic and solvophobic effects manifested in the h22 and h222 parameters for U and TMU in the studied organic solvents with a spatial H-bonding network.