Freezing temperatures of aqueous solutions containing formamide, acetamide, propionamide and N,N-dimethylformamide. Free energy of interaction between the CONH and CH2 groups in dilute aqueous solutions

Abstract

The freezing temperatures of dilute aqueous solutions of formamide, acetamide, propionamide and dimethylformamide have been determined. The data have been used, in association with appropriate enthalpy and heat capacity data, to calculate the pairwise free energy of self interaction coefficients at 298.15 K.

The results for the unsubstituted amides are predicted with reasonable accuracy using the group additivity approach developed previously. In contrast to the results for the enthalpies of interaction, the free energies of interaction of the disubstituted amides are not accurately predicted.