Potassium persulfate

Potassium persulfate
Other names potassium peroxydisulfate Anthion potassium perdisulfate
Identifiers
CAS number	7727-21-1 Y
PubChem	24412
EC number	231-781-8
UN number	1492
RTECS number	SE0400000
Jmol-3D images	Image 1
SMILES [O-]S(=O)(=O)OOS(=O)(=O)[O-].[K+].[K+]
InChI 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
Properties
Molecular formula	K2S2O8
Molar mass	270.322 g/mol
Appearance	white powder
Odor	odorless
Density	2.477 g/cm3
Melting point	<100 °C decomp.
Solubility in water	1.75 g/100 mL (0 °C) 5.29 g/100 ml (20 °C)
Solubility	insoluble in alcohol
Refractive index (nD)	1.467
Hazards
MSDS	ICSC 1133
EU Index	016-061-00-1
EU classification	Oxidant (O) Harmful (Xn) Irritant (Xi)
R-phrases	R8, R22, R36/37/38, R42/43
S-phrases	(S2), S22, S24, S26, S37
NFPA 704	0 2 1 OX
Flash point	Non-flammable
Related compounds
Other anions	Potassium sulfite Potassium sulfate Potassium peroxymonosulfate
Other cations	Sodium persulfate
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Not to be confused with potassium peroxymonosulfate.

Potassium persulfate (K₂S₂O₈) (also potassium peroxydisulfate or KPS) is a compound.

Uses

It is a food additive and it is used in organic chemistry as an oxidizing agent for instance in the Elbs persulfate oxidation, and in hair dye substances as whitening agent with hydrogen peroxide. It takes also an important role as initiator for emulsion polymerization.

For a review of its uses in organic chemistry, see Encyclopedia of Reagents for Organic Synthesis, vol. 1, pp 193-197(1995).

Preparation

Potassium persulfate can be prepared by electrolysis of a mixture between potassium sulfate and hydrogen sulfate at a high current density.

2 KHSO₄ → K₂S₂O₈ + H₂

It can also be prepared by adding potassium bisulfate (KHSO₄) to an electrolyzed solution of ammonium bisulfate (NH₄HSO₄).

Another reaction involving its formation is the following:

F₂ + 2KHSO₄ → K₂S₂O₆(O₂) + 2HF

However, the practical utility of this reaction is doubtful.

Precautions

Conditions/substances to avoid are: heat, flames, ignition sources, powdered metals, phosphorus, hydrides, organic matter, halogens, acids and alkalis.