Reaction Mechanisms as Meaning Preserving Structures: A Constraint Based Framework

Reaction mechanisms occupy a central position in chemistry, particularly in organic, bioorganic, and catalytic domains. Despite their ubiquity and pedagogical importance, mechanisms are neither directly observable nor formally derived objects. They function instead as representational constructs that organize complex chemical information into usable explanatory forms. This paper proposes a structural framework for understanding reaction mechanisms as meaning-preserving representations that emerge through constrained information filtering. Drawing on a general framework for how information becomes structured and persistent under constraint (Framework for Information and Form, FIF), we reinterpret intermediates, transition states, and mechanistic pathways not as ontological claims about molecular reality, but as stabilized informational nodes selected for their explanatory and predictive utility. This approach clarifies why mechanistic models are robust across contexts despite their heuristic character, explains where and why they break down, and offers principled guidance for developing new mechanistic representations in regimes of high chemical complexity.