Potassium persulfate is the inorganic compound with the formula K₂ S₂O₈. Also known as potassium peroxydisulfate, it is a white solid that is sparingly soluble in cold water, but dissolves better in warm water. This salt is a powerful oxidant, commonly used to initiate

polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many fo ...

Structure

The sodium and potassium salts are very similar. In the potasium salt, the O-O distance is 1.495Å. The individual sulfate groups are tetrahedral, with three short S-O distances near 1.43 and one long S-O bond at 1.65Å.

Preparation

Potassium persulfate can be prepared by electrolysis of a cold solution

potassium bisulfate Potassium bisulfate/ Potassium Sulphate is an inorganic compound with the chemical formula KHSO4 and is the potassium acid salt of sulfuric acid. It is a white, water-soluble solid. Preparation More than 1 million tons were produced in 1985 a ...

in sulfuric acid at a high current density.{{cite book, last=Brauer, first=Georg, title=Handbook of Preparative Inorganic Chemistry , volume=1 , edition=2nd , year=1963 , publisher=Academic Press , location=New York , isbn=978-0121266011 , page=392 , url=https://books.google.com/books?id=TLYatwAACAAJ&q=Handbook+of+Preparative+Inorganic+Chemistry : 2 KHSO₄ → K₂S₂O₈ + H₂ It can also be prepared by adding potassium bisulfate (KHSO₄) to a solution of the more soluble salt

ammonium peroxydisulfate Ammonium persulfate (APS) is the inorganic compound with the formula (NH4)2S2O8. It is a colourless (white) salt that is highly soluble in water, much more so than the related potassium salt. It is a strong oxidizing agent that is used as a cataly ...

(NH₄)₂S₂O₈. In principle it can be prepared by chemical oxidation of

potassium sulfate Potassium sulfate (US) or potassium sulphate (UK), also called sulphate of potash (SOP), arcanite, or archaically potash of sulfur, is the inorganic compound with formula K2SO4, a white water-soluble solid. It is commonly used in fertilizers, prov ...

using fluorine. Several million kilograms of the ammonium, sodium, and potassium salts of peroxydisulfate are produced annually.

Uses

This salt is used to initiate polymerization of various alkenes leading to commercially important polymers such as styrene-butadiene rubber and polytetrafluoroethylene and related materials. In solution, the dianion dissociates to give radicals:{{Ullmann , title = Peroxo Compounds, Inorganic , author=Harald Jakob , author2=Stefan Leininger , author3=Thomas Lehmann , author4=Sylvia Jacobi , author5=Sven Gutewort , doi = 10.1002/14356007.a19_177.pub2 : ₃SO-OSO₃sup>2− {{eqm 2 O₄sup>•− It is used in

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, ...

as an

oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...

,''Encyclopedia of Reagents for Organic Synthesis'', vol. 1, pp. 193–197(1995) for instance in the

Elbs persulfate oxidation The Elbs persulfate oxidation is the organic reaction of phenols with alkaline potassium persulfate to form ''para''-diphenols. The reaction is generally performed in water at room temperatures or below, using equimolar quantities of reagents. ...

phenol Phenol (also called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it ...

s and the

Boyland–Sims oxidation The Boyland–Sims oxidation is the chemical reaction of anilines with alkaline potassium persulfate, which after hydrolysis forms ''ortho''-hydroxyl anilines. The reaction is generally performed in water at room temperatures or below, using equim ...

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...

s. As a strong yet stable

bleaching agent Bleach is the generic name for any chemical product that is used industrially or domestically to remove color (whitening) from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically, to ...

it also finds use in various hair bleaches and lighteners. Such brief and non-continuous use is normally hazard free, however prolonged contact can cause skin irritation.{{cite journal, title=Final Report on the Safety Assessment of Ammonium, Potassium, and Sodium Persulfate, journal=International Journal of Toxicology, date=January 2001, volume=20, issue=3, doi=10.1080/10915810152630710, pmid=11766134 , last1 = Pang , first1 = S , last2 = Fiume , first2 = MZ, pages=7–21, s2cid=25763799 It has been used as an improving agent for flour with the E number E922, although it is no longer approved for this use within the EU.

Precautions

The salt is a strong oxidant and is incompatible with organic compounds. Prolonged skin contact can result in irritation.

References

{{reflist {{Potassium compounds {{E number infobox 920-929 Persulfates Potassium compounds Oxidizing agents Radical initiators