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Potassium persulfate





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Not to be confused with Potassium peroxymonosulfate.

Potassium persulfate is the inorganic compound with the formula K2S2O8. 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 polymerizations.

Potassium persulfate
Two potassium cations and one peroxydisulfate anion
Ball-and-stick model of the crystal structure
Potassium persulfate as a white powder
Names
Other names
  • potassium peroxydisulfate
  • Anthion
  • potassium perdisulfate
    • Identifiers

    CAS Number

    3D model (JSmol)
    ChemSpider
    ECHA InfoCard 100.028.893 Edit this at Wikidata
    EC Number
    • 231-781-8
    E number E922 (glazing agents, ...)

    PubChem CID
    RTECS number
    • SE0400000
    UNII
    UN number 1492

    CompTox Dashboard (EPA)

    • InChI=1S/2K.H2O8S2/c;;1-9(2,3)7-8-10(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2 ☒N

      Key: USHAGKDGDHPEEY-UHFFFAOYSA-L ☒N

    • InChI=1/2K.H2O8S2/c;;1-9(2,3)7-8-10(4,5)6/h;;(H,1,2,3)(H,4,5,6)/q2*+1;/p-2

      Key: USHAGKDGDHPEEY-NUQVWONBAA

    • [O-]S(=O)(=O)OOS(=O)(=O)[O-].[K+].[K+]

    Properties

    Chemical formula

    		 K2S2O8
    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)

    Solubility in water

    		 1.75 g/100 mL (0 °C)
    4.49 g/100 mL (20 °C)
    Solubility insoluble in alcohol

    Refractive index (nD)

    		 1.467
    Structure

    Crystal structure

    		 triclinic
    Hazards
    GHS labelling:

    Pictograms

    		 GHS03: Oxidizing GHS07: Exclamation mark GHS08: Health hazard

    Signal word

    		 Danger

    Hazard statements

    		 H272, H302, H315, H317, H319, H334, H335, H371

    Precautionary statements

    		 P220, P261, P280, P305+P351+P338, P342+P311
    NFPA 704 (fire diamond)
    NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
    2
    0
    1
    OX
    Flash point Non-flammable
    Lethal dose or concentration (LD, LC):

    LD50 (median dose)

    		 802 mg/kg (oral, rat)[2]
    Safety data sheet (SDS) ICSC 1133
    Related compounds

    Other anions

    		 Potassium sulfite
    Potassium sulfate
    Potassium peroxymonosulfate

    Other cations

    		 Sodium persulfate
    Ammonium 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 checkY☒N ?)

    Infobox references

    Structure

    edit

    The sodium and potassium salts are very similar. In the potassium salt, the O-O distance is 1.495 Å. The individual sulfate groups are tetrahedral, with three short S-O distances near 1.43 and one long S-O bond at 1.65 Å.[3]

    Preparation

    edit

    Potassium persulfate can be prepared by electrolysis of a cold solution potassium bisulfateinsulfuric acid at a high current density.[1][4]

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

    Uses

    edit

    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:[5]

    [O3SO-OSO3]2− ⇌ 2 [SO4]•−

    It is used in organic chemistry as an oxidizing agent,[6] for instance in the Elbs persulfate oxidationofphenols and the Boyland–Sims oxidationofanilines.

    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.[7] 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

    edit

    The salt is a strong oxidant and is incompatible with organic compounds. Prolonged skin contact can result in irritation.[7]

    References

    edit
    1. ^ a b Brauer, Georg (1963). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). New York: Academic Press. p. 392. ISBN 978-0121266011.
  • ^ Chambers, Michael. "ChemIDplus - 7727-21-1 - USHAGKDGDHPEEY-UHFFFAOYSA-L - Potassium persulfate". chem.nlm.nih.gov.
  • ^ Naumov, D.Yu.; Virovets, A.V.; Podberezskaya, N.V.; Novikov, P.B.; Politov, A.A. (1997). "Redetermination of the Crystal Structure of Potassium Peroxodisulfate (K2S2O8)". Zhurnal Strukturnoi Khimii. 38: 922-929.
  • ^ Girolami, G. S.; Rauchfuss, T. B.; Angelici, R. J. (1999). Synthesis and Technique in Inorganic Chemistry. Mill Valley, CA: University Science Books. ISBN 0935702482.
  • ^ Harald Jakob; Stefan Leininger; Thomas Lehmann; Sylvia Jacobi; Sven Gutewort. "Peroxo Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_177.pub2. ISBN 978-3527306732.
  • ^ Encyclopedia of Reagents for Organic Synthesis, vol. 1, pp. 193–197(1995)
  • ^ a b Pang, S; Fiume, MZ (January 2001). "Final Report on the Safety Assessment of Ammonium, Potassium, and Sodium Persulfate". International Journal of Toxicology. 20 (3): 7–21. doi:10.1080/10915810152630710. PMID 11766134. S2CID 25763799.

    • Retrieved from "https://en.wikipedia.org/w/index.php?title=Potassium_persulfate&oldid=1214529486"
      



    Last edited on 19 March 2024, at 14:28  





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