Kolbe electrolysis

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:

R₁COO⁻ + R₂COO⁻ → R₁−R₁ + R₁−R₂ + R₂−R₂

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

• Electrosynthesis
• Wurtz reaction

References

1. Kolbe, Hermann (1848). "Zersetzung der Valeriansäure durch den elektrischen Strom". Annalen der Chemie und Pharmacie 64 (3): 339–341. doi:10.1002/jlac.18480640346.
2. Kolbe, Hermann (1849). "Untersuchungen über die Elektrolyse organischer Verbindungen". 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

• "Kolbe Electrolysis". Organic Chemistry Portal. Retrieved 2007-10-22.