Chapter 7. Spontaneous Emergence of Chirality in Autocatalytic Cycle Models of the Soai Reaction

Abstract

The Soai reaction appears as an energy dissipative system thanks both to the typical round-by-round methodology which is an approximation of an open reactor and to the high exergonicity of the reaction of dialkylzinc with the carbaldehyde. It has been found that the high sensitivity of the Soai reaction to any cryptochiral induction, including the stochastic distribution of chiral signs of the fluctuations, is a manifestation of spontaneous mirror-symmetry breaking (SMSB). Its final non-equilibrium stationary state (NESS) cannot have a racemic composition. This bifurcation occurs only if an asymmetric autocatalytic system reaches a critical value of the entropy production. Several models, based on a Frank-like reaction network where enantioselective autocatalysis and mutual inhibition are provided by the involvement of oligomeric intermediates, have been established. However, the structures of the various intermediates and their detailed molecular mechanisms, despite remarkable experimental advances, are still intensely debated.