Spontaneous deracemizations is a challenging, multidisciplinary subject in current chirality research. In the absence of any chiral inductors, an achiral substance or a racemic composition is driven into an enantioenriched or even homochiral state through a selective energy input, e.g., chemical potential, photoirradiation, mechanical grinding, ultrasound waves, thermal gradients, etc. The most prominent examples of such transformations are the Soai reaction and the Viedma deracemization. In this review, we track the most recent developments in this topic and recall that many other deracemizations have been reported for solutions from mesophases to conglomerate crystallizations. A compiled set of simply available achiral organic, inorganic, organometallic, and MOF compounds, yielding conglomerate crystals, should give the impetus to realize new experiments on spontaneous deracemizations. Taking into account thermodynamic constraints, modeling efforts have shown that structural features alone are not sufficient to describe spontaneous deracemizations. As a guideline of this review, particular attention is paid to the physicochemical origin and symmetry requirements of such processes.

Nonlinear effects in asymmetric synthesis are identified by a nonlinear relationship between the enantiomeric excess of the product versus that of the chiral catalyst. Such information is not always sufficient to reveal if the active catalyst acts in its monomeric or dimeric form. Numerical simulations of two kinetic models including monomer and dimer catalysis with a Michaelis–Menten‐type reaction mechanism suggest that the nonlinear effects are mainly sensitive to an analogue of the Michaelis–Menten constant as well as to the diastereomeric energy difference between homochiral and heterochiral catalyst dimers. A practical monomer–dimer discrimination table is presented showing that the influence of the initial catalyst enantiomeric excess and the catalytic charge on the product enantiomeric excess and on the reaction half‐time together with the assessment of the kinetic order of the prochiral substrate are sufficient to assess whether the active catalyst acts in its monomeric or dimeric form.

A kinetic and thermodynamic model of the Soai reaction is presented. This allows the quantitative determination of five rates constants and one equilibrium constant. The model is realistic as it integrates the results of the most recently published XRD structural data and DFT calculations and selected experimental kinetic data. Equipped with the extracted parameters from the numerical fitting of the time evolution of both the substrate concentration and the enantiomeric excess, the model was able to mimic strong asymmetric amplification from extremely low initial enantiomeric excess and spontaneous mirror‐image symmetry breaking under “zero‐catalyst” conditions. It also reproduces the crystallization conditions by exhibiting the preferential accumulation of the corresponding oligomeric species in solution. An important point is also illustrated: the autocatalytic asymmetric amplification is not located on the expected easily detectable dimers but on the less concentrated tetrameric species.

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