The generation of reaction networks with RAIN. 2. Resonance structures and tautomerism

The program system RAIN for bilateral generation of reaction pathways requires a procedure that automatically represents each molecule to be entered into a reaction network in terms of all conceivable resonance and tautomeric structures. Thus ambiguities can be avoided, and substantially decreased numbers of required reaction steps for closing reaction pathways between starting materials and products of chemical reactions are achieved. It is shown how the formal reaction generator of RAIN can be guided by a set of constraints to produce only resonance or tautomeric structures of a considered molecule. The effects of these boundary conditions are shown in several illustrative examples.