Term: superacid
https://doi.org/10.1351/goldbook.S06135

Definition:
A medium having a high acidity, generally greater than that of 100 wt.% sulfuric acid. The common superacids are made by dissolving a powerful Lewis acid (e.g. SbF5) in a suitable Brønsted acid such as HF or HSO3F. (An equimolar mixture of HSO3F and SbF5 is known by the trade name 'magic acid'.) In a biochemical context 'superacid catalysis' is sometimes used to denote catalysis by metal ions analogous to catalysis by hydrogen ions. By analogy, a compound having a very high basicity, such as lithium diisopropylamide, is called a 'superbase'.

Related Terms:
1) acidity (<em>of a compound, of a medium</em>) (http://doi.org/10.1351/goldbook.A00079).
2) lewis acid (<em>of a compound, of a medium</em>) (http://doi.org/10.1351/goldbook.L03508).
3) brønsted acid (<em>of a compound, of a medium</em>) (http://doi.org/10.1351/goldbook.B00744).
4) basicity (<em>of a compound, of a medium</em>) (http://doi.org/10.1351/goldbook.B00611).
5) catalysis (<em>of a compound, of a medium</em>) (http://doi.org/10.1351/goldbook.C00874).

Source: PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1169 (https://doi.org/10.1351/pac199466051077)

Citation: 'superacid' 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.S06135

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