For both methods, we identify the possible site of reaction if the pK a value is within 1.5 pK a units of the lowest pK a value. This is slightly different from our previous approach. However, due to the higher complexity of the reaction and aromatic C-H sites are similar, we purposely allow the QM workflow and ML model to assess more sites as '1' or true site. When the pK a value is within 1.5 pK a units, we also ensure we are within the range or the uncertainty of the QM computed pK a values which have an MAE of 1.48, as discussed in the section -Computing pK a values. For compound 1, the ML model predicts two low pK a sites indicated by filled circles, where none correspond to the experimentally observed site of borylation (indicated by the arrow). However, the QM workflow predicts the correct site as the black ring indicates. Overall, the QM workflow accurately predicts four of the six borylation sites, although, in the case of compounds 2 and 6, there are additional sites with nearly identical pK a values. In the case of compound 3, most chemists would expect the pK a of pyrazole C-H sites to be considerably lower than on the benzene ring, suggesting that factors other than pK a determine the site of borylation for this compound. In the case of compound 5, the most likely explanation is that the site with the lowest QM computed pK a value is sterically hindered compared to the experimentally observed site of borylation. The ML model predicts three borylation sites correctly, but in the case of compound 5, there are two additional sites with low pK a values. One failure is for compound 3, where the QM workflow also fails, but for compounds 1 and 4, the ML model fails while the QM workflow accurately predicts the site of borylation. This indicates that these compounds are not well represented in the training set. Figure : Predicting the site of borylation for a set of six experimentally reported borylation reactions. Arrow: major experimental site/prediction by SoBo; black ring: QM computed lowest pK a +1.5; teal filled circle: ML predicted lowest pK a +1.5.