Figure depicts the reaction process in the embedding space in the PCA projection for the oxidation of alkanes (2a), alkenes (2b), and alcohols (2c). In each, only the embedding vector of the reactant-center carbon C r and product-center carbon C p are depicted in color, and commented by an arrow representing the reaction. Note that the arrows only represent the reactant and product end-points and do not represent the full reaction process, for which QM9 is not designed, however there has been some recent effort in are exploring the success of transfer learning to real-space quantities of chemistry that would include any part of the chemical space. The scatterplot in the background of the arrows, consists of all the carbon embeddings of QM9 labelled according to chemical moiety as was shown in ref . Other C embeddings in QM9 consisting of distinct functional groups from the reactant's functional group are shown in gray, whereas the colored groups (annotated in the caption) represent atoms in QM9 that have same functional groups as the reactants and products of the reaction.