Molecular recognition and effects of steric and geometric isomerism. Thermodynamic study of non-bonding interactions in aqueous solutions of cycloalkanols

Abstract

Enthalpies of dilution of binary and ternary aqueous solutions containing cyclobutanol, cyclopentanol, cyclohexanol, cycloheptanol, cyclooctanol, (1R,2R)-trans-cyclohexane-1,2-diol, (1S,2S)-trans-cyclohexane-1,2-diol, (1R,2S)-cis-cyclohexane-1,2-diol, (1R,2R)-trans-cyclopentane-1,2-diol, (1S,2S)-trans-cyclopentane-1,2-diol, (1R,2S)-cis-pentane-1,2-diol, cis-cyclooctane-1,2-diol, cis-cyclooctane-1,4-diol, cis-cyclooctane-1,5-diol, cis,cis-cyclohexane-1,3,5-triol and myo-inositol were determined by microcalorimetry at 298.15 K. Pairwise self- and cross-interaction coefficients of the virial expansion of the excess enthalpies were evaluated. The values of these coefficients are positive, depending in a very complex manner on the number of the hydroxy groups on the cyclic molecule and on steric and geometric isomerism. They have been interpreted according to an interaction model which indicates a preferential configuration between two hydrated interacting molecules, stabilized by the simultaneous juxtaposition of groups having the same action on water structure.