Elbs persulfate oxidation
{{Reactionbox
|Name = Elbs persulfate oxidation
|Type = Organic redox reaction
|NamedAfter = Karl Elbs
|Section3 = {{Reactionbox Identifiers
|RSC_ontology_id = 0000179
}}
}}
The Elbs persulfate oxidation is the organic reaction of phenols with alkaline potassium persulfate to form para-diphenols.{{cite journal|last1=Elbs | first1=K. |authorlink=Karl Elbs|journal=J. Prakt. Chem.|year=1893|volume=48|pages= 179–185|doi=10.1002/prac.18930480123|title=Ueber Nitrohydrochinon|language=German| url=https://zenodo.org/record/1427970 }} The reaction is generally performed in water at room temperatures or below, using equimolar quantities of reagents.
Image:Elbs Persulfate Oxidation Scheme.png
Several reviews have been published.{{cite journal | author = Sethna, S. M. | title = The Elbs Persulfate Oxidation | year = 1951 | journal = Chem. Rev. | volume = 49 | issue = 1 | pages = 91–101 | doi = 10.1021/cr60152a002}}{{cite journal|author1=Lee, J. B. |author2=Uff, B. C. |journal=Quart. Rev.|year=1967|volume=21|pages= 453|doi=10.1039/qr9672100429|title=Organic reactions involving electrophilic oxygen|issue=4}}{{cite book|author=Behrman, E. J. |title=Org. React.|year=1988|volume=35|pages= 421–511|doi=10.1002/0471264180.or035.02|chapter=The Persulfate Oxidation of Phenols and Arylamines (The Elbs and the Boyland-Sims Oxidations)|isbn=0471264180|title-link=Org. React.}}
Scope and mechanism
The reaction is disadvantaged by moderate to low chemical yields with recovery of starting material and complete consumption of the persulfate. It is suggested that the phenol in many cases is a catalyst converting the persulfate into a sulfate. Despite this, the Elbs reaction remains generally useful in a research setting, as it is simple to perform and is tolerant of a wide range of other functional groups, which are not oxidised under these conditions.
A reaction mechanism has been postulated which accounts for the observed para substitution featuring the tautomeric para carbanion of the starting phenolate ion:{{cite journal | author = Behrman, E. J. | title = The Elbs and Boyland-Sims peroxydisulfate oxidations | year = 2006 | journal = Beilstein Journal of Organic Chemistry | volume = 2 | issue = 1 | pages = 22 | doi = 10.1186/1860-5397-2-22 | pmid = 17090305 | pmc = 1697820 | doi-access = free }} It begins with nucleophilic displacement on the peroxide oxygen of the peroxodisulfate (peroxydisulfate) ion, to give an intermediate sulfate group (3), which is then hydrolyzed to the hydroxyl group.
See also
References
Category:Organic oxidation reactions
Add the following:
E. J. Behrman, The Elbs & Boyland-Sims Oxidations: An Updated Literature Survey. Mini-Rev. Org. Chem, 18(2021)621-625.