ESTIMATION OF PK(A) FOR ORGANIC OXYACIDS USING CALCULATED ATOMIC CHARGES

A method for the estimation of pK(a) from empirically calculated atomi c charges has been developed and tested on a diverse set of organic ox yacids. The approach involves a comparison of the atomic charges calcu lated for both the acid and the negative ion that is formed after loss of the acidic proton. These charges have been used in conjunction wit h the familiar concepts of induction and resonance to develop an accur ate formula to predict pK(a). Results for a set of 135 compounds, incl uding alcohols, phenols, and carboxylic acids, yielded a fit of pK(a) with r = 0.993 and an rms error of 0.455. (C) 1993 by John Wiley & Son s, Inc.