Figure 3.

Automatic inference of an overall rule by subsequent composition of graph transformation rules. The example is based on a sequence of reactions from [30], in which Eschenmoser describes how aldehydes act as catalysts for the hydrolysis of CN groups of the HCN tetramer. The left column depicts the mechanism as presented in [30]. An automated approach will, based on graph transformation rules, first generate a (potentially very large) chemical space (not depicted here). The depicted mechanism is then found as one of the solutions for the general question of enumerating hydrolysis pathways of HCN polymers that use glyoxylate (GLX: glyoxylate, CID 760) as a catalyst. In the depicted pathway, the tetramer of HCN (DAMN: tetramer of HCN, CID 2723951) is hydrolysed. The middle column depicts the left and right graph of each transformation rule p₁,…,p₅ that models the generalized reactions. The subsequently inferred rules p₁ (top), p₁•p₂,…, and the overall rule p₁•p₂•⋯•p₅ (bottom) are depicted in the right column. Note that, in general, these can be several composed overall rules, each expressing different atom traces. In this example there is only a single one.