Thermodynamics of amide+amine mixtures. 5. Excess molar enthalpies of N,N-dimethylformamide or N,N-dimethylacetamide+N-propylpropan-1-amine, +N-butylbutan-1-amine, +butan-1-amine, or +hexan-1-amine systems. ERAS results

TL;DR

This study measures excess molar enthalpies of specific amide-amine mixtures at 298.15 K, revealing interaction trends and validating the ERAS model's effectiveness in describing these thermodynamic properties.

Contribution

It provides new experimental data on excess molar enthalpies for various amide-amine mixtures and demonstrates the ERAS model's capability to accurately describe their thermodynamic behavior.

Findings

All excess molar enthalpies are positive, indicating predominant like-molecule interactions.

Replacing DMF with DMA lowers enthalpy values due to stronger amide-amide interactions.

The ERAS model successfully describes both enthalpy and volume excess properties.

Abstract

Excess molar enthalpies, $H_{\text{m}}^{\text{E}}$, over the whole composition range have been determined for the liquid mixtures N,N-dimethylformamide (DMF) or N,N-dimethylacetamide (DMA) + butan-1-amine (BA), or + hexan-1-amine (HxA), or + N-propylpropan-1-amine (DPA), or N-butylbutan-1-amine (DBA) at 298.15 K and at 0.1 MPa using a BT2.15 calorimeter from Setaram adapted to work in dynamic mode at constant temperature and pressure. All the $H_{\text{m}}^{\text{E}}$ values are positive, indicating that interactions between like molecules are predominant. The replacement of DMF by DMA in systems with a given amine leads to lower $H_{\text{m}}^{\text{E}}$ results, which have been ascribed to stronger amide-amide interactions in DMF mixtures. The replacement of HxA by DPA in systems with a given amide leads to slightly higher $H_{\text{m}}^{\text{E}}$ values, as interactions between unlike molecules are weaker for the latter. Structural effects in the investigated solutions are also present, since the corresponding excess molar volumes ($V_{\text{m}}^{\text{E}}$), previously determined, are negative or slightly positive. The systems have been characterized in terms of the ERAS model reporting the interaction parameters. The model correctly describes both $H_{\text{m}}^{\text{E}}$ and $V_{\text{m}}^{\text{E}}$. The application of the model suggests that, in the systems under study, solvation effects are of minor importance and that physical interactions are dominant.