Reaktionsstufe

Reaktionsstufe is a German term that translates as “reaction step” or “reaction stage” and is used principally in chemistry and related fields to denote an individual elementary transformation within a multistep process. In a reaction mechanism each Reaktionsstufe represents a distinct molecular event, such as bond formation, bond cleavage, proton transfer, or rearrangement, and is usually illustrated by an arrow diagram that connects reactants, intermediates and products. The concept allows chemists to dissect complex overall reactions into a sequence of simpler, kinetically and thermodynamically defined steps, facilitating the analysis of reaction rates, activation energies and the influence of catalysts.

In organic synthesis Reaktionsstufen are often numbered sequentially (Stufe 1, Stufe 2, …) to describe the order of operations required to build a target molecule. The identification of rate‑determining Reaktionsstufe, the slowest step that controls the overall reaction velocity, is central to mechanistic studies and to the optimization of reaction conditions. In industrial process engineering the term is also applied to batch or continuous processes, where each Reaktionsstufe corresponds to a distinct unit operation, such as mixing, heating, or separation, and is monitored for yield and safety.

The formal description of Reaktionsstufen is governed by the principles of chemical kinetics and thermodynamics, and their representation follows the conventions of IUPAC nomenclature and standard reaction‑mechanism notation.