Potassium persulfate

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Potassium persulfate
Two potassium cations and one peroxydisulfate anion
Ball-and-stick model of the crystal structure
Potassium persulfate as a white powder
Other names
potassium peroxydisulfate
potassium perdisulfate
7727-21-1 YesY
ChemSpider 22821 N
EC Number 231-781-8
Jmol interactive 3D Image
PubChem 24412
RTECS number SE0400000
UN number 1492
Molar mass 270.322 g/mol
Appearance white powder
Odor odorless
Density 2.477 g/cm3[1]
Melting point < 100 °C (212 °F; 373 K) (decomposes)
1.75 g/100 mL (0 °C)
4.49 g/100 ml (20 °C)
Solubility insoluble in alcohol
Safety data sheet ICSC 1133
Oxidant (O)
Harmful (Xn)
Irritant (Xi)
R-phrases R8, R22, R36/37/38, R42/43
S-phrases (S2), S22, S24, S26, S37
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g., calcium Special hazard OX: Oxidizer. E.g., potassium perchlorateNFPA 704 four-colored diamond
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
802 mg/kg (oral, rat)[2]
Related compounds
Other anions
Potassium sulfite
Potassium sulfate
Potassium peroxymonosulfate
Other cations
Sodium persulfate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references
Not to be confused with potassium peroxymonosulfate.

Potassium persulfate is the inorganic compound with the formula K2S2O8. Also known as potassium peroxydisulfate or KPS, it is a white solid that is highly soluble in water. This salt is a powerful oxidant, commonly used to initiate polymerizations.


Potassium persulfate can be prepared by electrolysis of a cold solution potassium bisulfate in sulfuric acid at a high current density.[1]

2 KHSO4 → K2S2O8 + H2

It can also be prepared by adding potassium bisulfate (KHSO4) to a solution of the more soluble salt ammonium peroxydisulfate (NH4)2S2O8. In principle it can be prepared by chemical oxidation of potassium sulfate using fluorine.


This salt is used to initiate polymerziation 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:[3]

[O3SO-OSO3]2− \overrightarrow{\leftarrow} 2 [SO4]

It is used in organic chemistry as an oxidizing agent,[4] for instance in the Elbs persulfate oxidation of phenols and the Boyland–Sims oxidation of anilines.

As a strong yet stable bleaching agent 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.[5] 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.


The salt is a strong oxidant and is incompatible with organic compounds. Prolonged skin contact can result in irritation.[5]


  1. ^ a b F. Feher, "Potassium Peroxydisulfate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 392.
  2. ^ http://chem.sis.nlm.nih.gov/chemidplus/rn/7727-21-1
  3. ^ Harald Jakob, Stefan Leininger, Thomas Lehmann, Sylvia Jacobi, Sven Gutewort (2005), "Peroxo Compounds, Inorganic", Ullmann's Encyclopedia of Industrial Chemistry, Weinheim: Wiley-VCH, doi:10.1002/14356007.a19_177.pub2 
  4. ^ Encyclopedia of Reagents for Organic Synthesis, vol. 1, pp 193-197(1995)
  5. ^ a b "Final Report on the Safety Assessment of Ammonium, Potassium, and Sodium Persulfate". International Journal of Toxicology 20 (3): 7-21. January 2001. doi:10.1080/10915810152630710.