Kolbe–Schmitt reaction
| Kolbe–Schmitt reaction | |
|---|---|
| Named after | Hermann Kolbe Rudolf Schmitt |
| Reaction type | Addition reaction |
| Identifiers | |
| Organic Chemistry Portal | kolbe-schmitt-reaction |
| RSC ontology ID | RXNO:0000182 |
The Kolbé–Schmidt reaction or Kolbe process (named after Hermann Kolbe and Rudolf Schmitt) is a carboxylation chemical reaction that proceeds by heating sodium phenoxide (the sodium salt of phenol) with carbon dioxide under pressure (100 atm, 125 °C), then treating the product with sulfuric acid. The final product is an aromatic hydroxy acid which is also known as salicylic acid (the precursor to aspirin).[1][2][3]
By using potassium hydroxide, 4-hydroxybenzoic acid is accessible, an important precursor for the versatile paraben class of biocides used e.g. in personal care products.
Reaction mechanism
The Kolbe–Schmitt reaction proceeds via the nucleophile addition of a phenoxide, classically sodium phenoxide (NaOC6H5), to carbon dioxide to give the salicylate. The final step is reaction of the salicylate with acid to form the desired salicylic acid.
References
- ↑ Hermann Kolbe (1860). "Ueber Synthese der Salicylsäure". Annalen der Chemie und Pharmacie 113 (1): 125–27. doi:10.1002/jlac.18601130120.
- ↑ R. Schmitt (1885). "Beitrag zur Kenntniss der Kolbe'schen Salicylsäure Synthese". Journal für Praktische Chemie 31 (1): 397–411. doi:10.1002/prac.18850310130.
- ↑ A. S. Lindsey and H. Jeskey (1957). "The Kolbe-Schmitt Reaction". Chem. Rev. 57 (4): 583–620. doi:10.1021/cr50016a001. (Review)
External links
- English Translation of Kolbe's seminal 1860 German article in Annalen der Chemie und Pharmacie that describes the discovery of this reaction. English title: 'On the syntheses of salicylic acid'; German title "Ueber Synthese der Salicylsäure".
- An animation of the reaction mechanism.
