Elbs persulfate oxidation

Elbs the oxidation (also called Elbs persulfate oxidation) is a name of reaction in organic chemistry. The reaction was first in 1893 by the German chemist Karl Elbs (1858 - 1933) published. It is used in the synthesis of hydroquinones from phenols. Suitable oxidizing agents are salts of peroxodisulphuric such as potassium. The Elbs oxidation is not to be confused with the Elbs reaction for the synthesis of polynuclear aromatics.

Reaction mechanism

The Elbs oxidation is carried out in basic medium. First deprotonated phenol (1) to the phenolate (2). The carbon atom in the para position then nucleophilically attacks the oxygen atom of the peroxodisulfate to, thereby, an aromatic sulfate, 5 is formed. This is then hydrolyzed so that the desired product 8 is released.

The para- product is formed in this case with good selectivity. Catechol or its derivatives are then formed when the para position is already occupied by a substituent. However, the achievable yields are moderate.