DIELECTRIC BEHAVIOR OF AQUEOUS-SOLUTIONS OF D-MANITOL

The purpose of our work was the experimental determination of the dipo le moment of D-manitol in aqueous solution by optical, dielectric and volumetric determinations and to find an association pattern between s olute and solvent. With Buckinghams' equation we obtained an experimen tal dipole moment (mu) of 676 D. Based on the discrepancy between the dipole moment value of the isolated manitol molecule (0.22 D) and its average value in aqueous solution we studied several vectorial calcula tion alternatives. Considering interatomic distances, angles and bond lengths, and the ellipsoidal cavity boundaries determined by shape fac tor and cell constants we postulate that the poliol is attached throug h hydrogen bonds to thirteen water molecules. This is confirmed by the experimental solute molar partial volume value that is smaller than t he theoretical one.