Hofer-Moest reaction

What is Hofer-Moest reaction?

The Hofer-Moest reaction, discovered in 1902, involves the electrolytic decarboxylation of aliphatic acids in neutral or alkaline solutions with an inert anion, like sulfate, phosphate, perchlorate, carbonate, or bicarbonate, resulting in the corresponding alcohols with one less carbon.

Hofer-Moest reaction - general reaction scheme - Hofer-Moest oxidation - abnormal Kolbe reaction
Hofer-Moest reaction

Hofer-Moest reaction is typically conducted with a platinum anode, as it favors the carbonium ion product over the radical product, which leads to the formation of hydrocarbon via the Kolbe electrolytic synthesis. Hence, the reaction is also known as the Hofer-Moest oxidation or the abnormal Kolbe reaction. The resulting alcohols are called Hofer-Moest products, with some minor products formed as well, such as olefins, ketones, esters, and ethers.

The use of a carbon anode has been found to eliminate the Kolbe product without the addition of salts or increased pH.

This reaction has also been applied to amino acid derivatives and the anodic methoxylation of amides or carbamates to N-acyliminium ions for amidoalkylation. Increasing the frequency in pulsed electrolysis has also been found to favor Hofer-Moest products.

Hofer-Moest reaction is valuable for transforming carboxylic acids into alcohols with a carbon atom reduced and also for decarboxylating amino acids and polypeptides.

References

Hofer, H. and Moest, M. (1902), Ueber die Bildung von Alkoholen bei der Elektrolyse fettsaurer Salze. [On the formation of alcohols during the electrolysis of fatty acid salts] Justus Liebigs Ann. Chem., 323: 284-323. https://doi.org/10.1002/jlac.19023230304

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