Enthalpies of mixing of water withN,N-disubstituted amides of aliphatic carboxylic acids

The enthalpies of mixing ofN,N-dialkylpropionamides with water were measured at 298.15 K. A comparative analysis of enthalpy effects (H ^E) of mixing of water withN,N-disubstituted amides of formic, acetic, and propionic acids was performed. It was established that theH ^E values depend on the length of theN,N-alkyl substituents and the size of acidic radicals. The size of the nonpolar group and the electron-donor ability of amide molecules primarily affect the enthalpy of mixing. The relative electron-donor abilities of the amides were estimated by the calorimetric method. The results obtained were discussed by invoking thermochemical data for aqueous solutions of hexamethylphosphoric triamide. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1805–1810, October, 1997.