Kolbe electrolysis

"Kolbe reaction" redirects here. For the carboxylation of phenols, see Kolbe–Schmitt reaction.

The Kolbe electrolysis or Kolbe reaction is an organic reaction named after Hermann Kolbe.[1][2] The Kolbe reaction is formally a decarboxylative dimerisation of two carboxylic acids (or carboxylate ions) The overall general reaction is:

If a mixture of two different carboxylates are used, all combinations of them are generally seen as the organic product structures:

3 R1COO− + 3 R2COO− → R1−R1 + R1−R2 + R2−R2 + 6 CO2 + 6 e−

The reaction mechanism involves a two-stage radical process: electrochemical decarboxylation gives a radical intermediate, then two such intermediates combine to form a covalent bond.[3] As an example, electrolysis of acetic acid yields ethane and carbon dioxide:

CH3COOH → CH3COO− → CH3COO· → CH3· + CO2
2CH3· → CH3CH3

Another example is the synthesis of 2,7-dimethyl-2,7-dinitrooctane from 4-methyl-4-nitrovaleric acid:[4]

See also

References

  1. ↑ Kolbe, Hermann (1848). "Zersetzung der Valeriansäure durch den elektrischen Strom" [Decomposition of valeric acid by an electric current]. Annalen der Chemie und Pharmacie. 64 (3): 339–341. doi:10.1002/jlac.18480640346.
  2. ↑ Kolbe, Hermann (1849). "Untersuchungen über die Elektrolyse organischer Verbindungen" [Investigations of the electrolysis of organic compounds]. Annalen der Chemie und Pharmacie. 69 (3): 257–372. doi:10.1002/jlac.18490690302.
  3. ↑ Vijh, A. K.; Conway, B. E. (1967). "Electrode Kinetic Aspects of the Kolbe Reaction". Chem Rev. 67 (6): 623–664. doi:10.1021/cr60250a003.
  4. ↑ Sharkey, W. H.; Langkammerer, C. M. (1973). "2,7-Dimethyl-2,7-dinitrooctane". Org. Synth.; Coll. Vol., 5, p. 445

External links

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