Autocatalytic

Autocatalytic refers to a process in which one of the products of a reaction acts as a catalyst for that same reaction. In such systems, the production of the product accelerates further production, creating positive feedback. The defining feature is that the reaction rate depends on the concentration of a species that is itself generated by the reaction.

A common simple model is A + B -> 2B, where B released by the reaction acts as a catalyst for more formation of B. The rate can be proportional to [A][B], so as B accumulates, the overall rate increases and the system may show nonlinear, often sigmoidal, kinetics. Autocatalysis can occur in many chemical contexts, including organic, inorganic, and polymerization processes, and it may take the form of autocatalytic cycles or feedback loops within a reaction network.

In biology and origin-of-life studies, autocatalysis is a central concept. Autocatalytic sets are networks of molecules that collectively catalyze each other’s formation, enabling self-sustaining systems. The idea has been explored in models such as hypercycles, proposed by Eigen and Schuster, which describe linked autocatalytic processes that could support the emergence and maintenance of self-reproducing systems.

Practical implications include both challenges and opportunities. Autocatalysis can complicate reactor design and control due to positive feedback and potential runaway behavior, requiring inhibitors, dilution, or careful thermal management. Conversely, autocatalytic principles are exploited in certain catalytic systems and in studies of self-assembly and material synthesis.