THEORETICAL-STUDY OF THE SOLVENT EFFECT ON FUNCTIONAL-GROUP PROPERTIES AND ON THE CHARGE-DISTRIBUTION AND ACIDITY OF ALKYL-SUBSTITUTED ALCOHOLS

For a number of functional groups, the group electronegativity and har dness in the gas phase and in different solvents was calculated using the recently introduced self-consistent isodensity polarized continuum model (SCI-PCM). The results indicate that the groups become less ele ctronegative and less hard with increasing dielectric constant. Using the calculated functional group properties and Sanderson's electronega tivity equalization principle, charge distributions in the alkyl alcoh ols X-OH and their conjugated bases XO- (with X = -CH3, -CH2CH3, and - CH(CH3)(2) are determined in solution. The calculated charge distribut ions are used in a study of the inversion of alkyl alcohol acidity fro m gas phase to aqueous solution. Relative acidities are calculated in the gas phase and in aqueous solution for methanol, ethanol, 2-propano l and tert-butanol. The experimentally observed inversion of the acidi ty sequences of these systems is reproduced, and special importance is assigned to the stabilization energy of the conjugate bases in both m edia.