Term: pseudo-catalysis
https://doi.org/10.1351/goldbook.P04924

Definition:
If an acid or base is present in nearly constant concentration throughout a reaction in solution (owing to buffering or the use of a large excess), it may be found to increase the rate of that reaction and also to be consumed during the process. The acid or base is then not a catalyst and the phenomenon cannot be called catalysis according to the well-established meaning of these terms in chemical kinetics, although the mechanism of such a process is often intimately related to that of a catalysed reaction. It is recommended that the term pseudo-catalysis be used in these and analogous cases (not necessarily involving acids or bases). For example, if a Brønsted acid accelerates the hydrolysis of an ester to a carboxylic acid and an alcohol, this is properly called acid catalysis, whereas the acceleration, by the same acid, of hydrolysis of an amide should be described as pseudo-catalysis by the acid: the 'acid pseudo-catalyst' is consumed during the reaction through formation of an ammonium ion. The terms 'general acid pseudo-catalysis' and 'general base pseudo-catalysis' may be used as the analogues of general acid catalysis and general base catalysis. The term 'base-promoted', 'base-accelerated' or 'base-induced' is sometimes used for reactions that are pseudo-catalysed by bases. However, the term 'promotion' also has a different meaning in other chemical contexts.

Related Terms:
1) catalyst (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.C00876).
2) catalysis (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.C00874).
3) mechanism (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.M03804).
4) brønsted acid (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.B00744).
5) general acid catalysis (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.G02609).
6) general base catalysis (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.G02610).
7) hydrolysis (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.H02902).
8) acceleration (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.A00051).
9) promotion (<em>of a reaction</em>) (http://doi.org/10.1351/goldbook.P04877).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1153 (https://doi.org/10.1351/pac199466051077)

Citation: 'pseudo-catalysis' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.P04924

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