HYDROPHILIC GROUPS DETERMINE PREFERENTIAL CONFIGURATIONS IN AQUEOUS-SOLUTIONS - A CALORIMETRIC STUDY OF MONOCARBOXYLIC ACIDS AND MONOALKYLAMINES AT 298.15-K

Enthalpies of dilution of binary aqueous solutions containing monocarb oxylic acids and monoalkylamines have been determined by microcalorime try at 298.15 K. Pairwise self-interaction coefficients of the virial expansion of the excess enthalpies were evaluated and compared with th ose obtained for alkan-1-ols. The values of the coefficients are posit ive and increase differently with increasing number of carbon atoms on the alkyl chain, depending on the nature of the functional groups. Fo r all series, starting with the terms containing five methylene groups , the coefficients tend to attain a constant value. Attempting to expl ain this behaviour, the attention was focused on the nature of the hyd ration of the alkyl chain. (C) 1997 Elsevier Science B.V.