ANALYSIS OF SOLUTE SOLVENT INTERACTIONS FOR THE ACIDITY OF ACETIC-ACIDS BY THEORETICAL DESCRIPTORS

Quantitative structure-activity relationships (QSAR) are used now routinely to relate the biological activities and chemical properties of molecules to their molecular structural features. When theoretically determined descriptors are used in QSAR, quick and good a priori predictions of molecular properties can be accomplished. In this study, theoretical linear solvation energy relationship descriptors are used to model the solute/solvent interactions that influence the acidity of substituted acetic acids in different solvents. A multilinear regression (MLR) analysis approach is used to generate equations, and owing to the goodness of the fit of the different MLR equations, these descriptors account fairly well for the significant solute/solvent interactions that affect the acidity. Good agreement is obtained between the acidities predicted by this method and the experimental acidities, which are determined from potentiometric titrations, for twenty-five substituted acetic acids in seven solvents. For the acidity of substituted acetic acids where good acidity predictions were not achieved by this method, a detailed discussion is presented.