PyCaret version 2.2.0 32 is used as an initial screening of 17 regression models and 13 classification models to find promising models. To evaluate the performance of the models, we use a 5-fold cross-validation scheme of the atomic data for atoms in molecules belonging to the randomly split training set. The atomic data consist of the sorted-shell descriptor with 5 shells in combination with either a binary label corresponding to whether or not a bromination reaction has been experimentally observed on the specific site or the calculated proton affinity obtained by the original RegioSQM20 method. The sorted-shell descriptor with 3 shells and the combinatorial descriptor were also tested in this initial screening, but the ranking of the different models were similar to those presented in Figures and. .