Excess molar enthalpies of N,N-dimethylformamide with ketones at 298.15 K

Excess molar enthalpies (H-E) at 298.15 K of N,N-dimethylformamide with a series of ketones: methyl ethyl ketone (MEK), methyl propyl ketone (MIPK), diethyl ketone (DEK), methyl isobutyl ketone (MIBK), cyclopentanone (CP) and cyclohexanone (CH) have been measured by using a Parr 1451 solution calorimeter, as a function of mole fraction of the N,N-dimethylformamide. The experimental H-E values are positive for ail binary mixtures over the entire range of composition. The excess enthalpies of the above mentioned binary systems, were used to discuss interactions between the ketonic (>CO) and DMF molecules. The results are interpreted to gain insight into the changes in molecular association equilibria and structural effects in these systems. When the compounds are mixed, the changes that occur in association equilibria are evidently rupture of the hydrogen bonds in pure compounds and the formation of OH... CO hydrogen bonds between the compounds. (C) 1999 Elsevier Science B.V. All rights reserved.