prereaction

Prereaction refers to the preparatory steps and conditions required before a chemical reaction actually begins. These steps are part of the experimental setup and may influence the outcome of the reaction, including yield, rate, and selectivity. Prereaction activities encompass preparing reagents, solvents, and equipment, as well as establishing the reaction environment.

Common prereaction activities include purifying and drying reagents, activating catalysts or reagents in situ, and preparing solvents by degassing or drying. Organometallic or sensitive reagents may be generated immediately before use, or activated catalysts may be pretreated to generate the active species. Solvent preparation often involves distillation or filtration to remove water and impurities, and degassing to minimize oxygen or moisture. Inert atmosphere techniques, such as using a nitrogen or argon blanket, are also typical prereaction measures for air- or moisture-sensitive systems. Temperature equilibration, stirring, and correct mixing order of reagents are additional prereaction considerations.

The prereaction phase is distinct from the main chemical transformation and from post-reaction workup. In experimental reporting, prereaction steps are described to ensure reproducibility, sometimes under separate headings like preparation or setup. While prereaction steps can be routine or straightforward, they can also be critical bottlenecks or sources of induction periods in kinetics. In some contexts, particularly in catalysis or materials science, prereaction steps are treated as integral parts of the process, influencing the effective activity and efficiency of the system. Overall, prereaction encompasses all preparatory actions needed to create suitable starting conditions for a reaction.