Excess molar enthalpies of binary mixtures of formamide with butanol at 298.15 K: Application of Prigogine–Flory–Patterson theory and Treszczanowicz–Benson association model

Excess molar enthalpies ( H m E ) of formamide (1) + 1-butanol or 2-methyl-1-propanol or 2-methyl-2-propanol (2) mixtures have been measured at 298.15 K over the entire composition range using flow micro calorimeter. The excess enthalpy data along with previously published excess volumes data ( V m E ) (M. Rani, S. Maken, J. Ind. Eng. Chem. 18 (2012) 1694) have been utilised to study the thermodynamics of molecular interactions in terms of Prigogine–Flory–Patterson theory and Treszczanowicz–Benson association model with a Flory contribution term. The Treszczanowicz–Benson model was developed for alkane + alkanol systems considering Mecke–Kempter type of association in alkanol. In this paper the Treszczanowicz–Benson association model was applied, for the first time, to binary mixtures containing both components associated (butanol and formamide) through hydrogen bonding. In both the cases, when either of formamide or butanol was assumed to be associated, the calculated H m E and V m E values compared reasonably well with the corresponding experimental data, but the agreement is not very impressive for excess enthalpy in formamide + 2-methyl-2-propanol mixtures. Extent of inter-molecular H-bonding in formamide and butanols in their binary mixtures was also reflected in their molar enthalpy of association of H-bonding Δ h H 0 .