Substances reported in reactions, either in patent or journals, between 1800 and 2021 were dumped from the Reaxys ® database on the 21 st February 2022. For the resulting 18,375,580 substances, their substance ID, molecular formula (MF), and year of first publication were retrieved. As our approach to similarity relies on MFs, all isomers were collapsed into the corresponding MF; each one was assigned the ID and year of the oldest substance associated with it. This led to a dataset of 3,448,632 MFs labelled with year of publication. Further details in SI 7.1.