EFFECT OF DIOL MOLECULAR-STRUCTURE ON THE MOLAR ENTHALPIES OF SOLUTION OF NACL IN (WATER PLUS BUTANEDIOL)

The enthalpies of dissolution of NaCl in aqueous solutions of isomeric butanediols {1,2-butanediol (1,2BD), 2,3-butanediol (2,3BD), 1,3-buta nediol (1,3BD), and 1,4-butanediol (1,4BD)} were measured within the w hole available range of salt concentrations. The standard enthalpies o f solution Delta(sol)H(m)(infinity) against the mixed solvent composit ion exhibit their maxima in the water-rich region of all the investiga ted mixtures. The positions and heights of the maxima depend on the ki nd of isomeric diol molecule. Enthalpic pair interaction coefficients h(xy) for (butanediol + NaCl) in water were calculated and analysed. I n conclusion, it is suggested that interactions among the diol molecul es influence their interactions with the investigated electrolyte. (C) 1997 Academic Press Limited.