Thermodynamic investigations of ternary o-toluidine + tetrahydropyran + N,N-dimethylformamide mixture and its binaries at 298.15, 303.15 and 308.15 K

► The ρ and u data of OT + THP + DMF and its binaries have been measured as a function of composition. ► The HE data of same set of binary mixtures have also been measured over entire composition at 308.15 K. ► The ρ and u data of binary and ternary mixtures have been utilized to determine their VE and κSE. ► The observed thermodynamic properties of binary and ternary mixtures have been analyzed in terms of Graph theory. ► It has been observed that Graph theory correctly predicts the sign as well as magnitude of thermodynamic properties.