Kolbe electrolysis

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"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:

Electrólisis de Kolbe.png

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]

Kolbe electrolysis, synthesis of 2,7-Dimethyl-2,7-dinitrooctane

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