Reaction role assignments that distinguish reactants, reagents, catalysts, and solvents are sometimes used in downstream tasks such as reaction condition recommendation. The reaction role of a compound is context-dependent, e.g., a chemical can serve as a solvent or a reactant in different reactions, and not explicitly stated in procedure text, so this is also not a pure information extraction task. However, since this implicit information is included in fine-tuning, the fine-tuned model learns the conventions about role assignment in a generalizable way, and the inferred assignment is directly available in the reaction_role field. Since each Compound message is allowed to have only one reaction_role, the reaction role assignment is a standard classification problem. While the ORD data schema has more than 10 types of reaction roles defined to cover a variety of situations, in this dataset only three are used for input compounds (CATALYST, REACTANT, SOLVENT). We exclude ProductCompound messages in this section because they always have a reaction_role of PRODUCT in this dataset. We also evaluate a popularity baseline that makes classification decisions based on the role frequency of compounds in the training dataset; roles are uniformly randomly assigned in the case of ties or unseen compounds.