The quantitative structure-property relationship (QSPR) method was performed to study the relationship between pKa values and electrotopological state indices of 45 organic compounds in DMSO. The relationship was expressed as: pKa＝－1.545×E2＋0.633×E4－0.737×E5＋0.973×E6－4.048×E7－1.456×E8＋0.628×E9＋28.650 with R＝0.991, and S＝0.828. Furthermore, leave-one-out cross validation was performed, which confirmed the good stability and powerful prediction of this model. The result indicated that the electrotopological state indices could be effectively used for the prediction of pKa values of organic compounds.

Key words: electrotopological state index, QSPR, pKa value