To group synthesis protocols together, we related individual syntheses to one another by the identity of the reagents used only. To calculate the mathematical relationship between different synthesis protocols the list of chemicals was first vectorised, creating a numerical representation of the chemical combination used in each synthesis. Briefly, an 𝑀 × 𝑁 matrix was created, where M is the number of synthesis protocols, and N is the number of unique chemicals present across all of synthesis protocols studied. To reduce noise in the data, only synthesis protocols containing 2-methylimidazole were considered, and metal sources were grouped by chemical substructures as described previously. In total, 139 unique chemicals were identified across 1134 synthesis protocols.