Another difference in our previous work was using a reaction matrix concept, where each reaction component was described by a of molecular features defining a unique reaction matrix (Figure ). While it was possible to do aforementioned binary prediction using machine learning methods, it was not suitable for comparing or identifying any given reaction versus similar ones in the literature. Therefore, we considered a different approach to define descriptors that would be more suitable for reaction classifications. In addition, we wanted a template free approach and not work with the common reaction mapping and its pros and cons. 15