The molecules with the highest deviations in the prediction of experimental logDpH using logDEq1 are displayed in Figure . The chemical nature of the outliers is dominated by the presence of ionic species because these compounds were experimentally measured under extreme pH conditions. These deviations correspond to the theoretical frameworks of Eqs. 1 and 2. Thus, the inclusion of the term P I app in Eq. 2 significantly corrects the prediction. Figure also shows various polyacids with pKa values separated by more than four orders of magnitude, allowing us to analyze the distribution coefficient using the most acidic pKa. Bases with entries 16, 151-152 have multiple protonation sites, while acids with entries 77, 78, and 87 have two deprotonation sites. More complex thermodynamic models can be considered for these molecules. However, as mentioned above, because of the separation of their pKa, the consideration of P I app for the carboxylate species with logDEq.2 is enough to remarkably increase the accuracy of the lipophilicity prediction of these compounds to extreme pH where one charged species can predominate over the others.