A well-known regularised reaction SMILES tokenisation method has been proposed by Schwaller et al. , to deliver the promising reaction prediction tool -Molecular Transformer. In this method, all atoms and regular used expressions in reaction SMILES are separated into tokens, such as "C", "Br", "@" and ")". Although this regularised tokenisation was implemented in multiple related works, it was not used here. This approache discretises a molecule into multiple tokens, which makes it harder to learn from the semantic context of a molecule's SMILES string.