The peroxydisulfate ion, , is an
oxyanion An oxyanion, or oxoanion, is an ion with the generic formula (where A represents a chemical element and O represents an oxygen atom). Oxyanions are formed by a large majority of the chemical elements. The formulae of simple oxyanions are determine ...
, the anion of
peroxydisulfuric acid
Peroxydisulfuric acid is an inorganic compound with a chemical formula . Also called Marshall's acid after Professor Hugh Marshall, who discovered it in 1891.
Structure and bonding
This oxoacid features sulfur in its +6 oxidation state and a pe ...
. It is commonly referred to as
persulfate
A persulfate (sometimes known as peroxysulfate or peroxodisulfate) is a compound containing the anions or . The anion contains one peroxide group per sulfur center, whereas in , the peroxide group bridges the sulfur atoms. In both cases, sulfu ...
, but this term also refers to the
peroxomonosulfate
The peroxomonosulfate ion, , is a sulfur oxoanion. It is sometimes referred to as the persulfate ion, but this term also refers to the peroxydisulfate ion, .
Its other IUPAC names are sulfuroperoxoate and trioxidoperoxidosulfate(2−).
Compoun ...
ion, . It is also called ''peroxodisulfate''.
Approximately 500,000 tons of salts containing this anion are produced annually. Important salts include
sodium persulfate
Sodium persulfate is the inorganic compound with the formula Sodium, Na2Sulfur, S2Oxygen, O8. It is the sodium salt of peroxydisulfuric acid, H2S2O8, an oxidizing agent. It is a white solid that dissolves in water. It is almost non-hygroscopic an ...
(Na
2S
2O
8),
potassium persulfate
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, c ...
(K
2S
2O
8), and
ammonium persulfate
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 ...
((NH
4)
2S
2O
8). These salts are colourless, water-soluble solids that are strong oxidants.:
Applications
Salts of peroxydisulfate are mainly used to initiate the polymerization of various
alkenes
In organic chemistry, an alkene is a hydrocarbon containing a carbon–carbon double bond.
Alkene is often used as synonym of olefin, that is, any hydrocarbon containing one or more double bonds.H. Stephen Stoker (2015): General, Organic, an ...
, including
styrene
Styrene () is an organic compound with the chemical formula C6H5CH=CH2. This derivative of benzene is a colorless oily liquid, although aged samples can appear yellowish. The compound evaporates easily and has a sweet smell, although high concen ...
,
acrylonitrile
Acrylonitrile is an organic compound with the formula and the structure . It is a colorless, volatile liquid although commercial samples can be yellow due to impurities. It has a pungent odor of garlic or onions. In terms of its molecular ...
, and fluoroalkenes.
Polymerization
In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer, monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are ...
is
initiated
Initiation is a rite of passage marking entrance or acceptance into a group or society. It could also be a formal admission to adulthood in a community or one of its formal components. In an extended sense, it can also signify a transformation ...
by the
homolysis of the peroxydisulfate:
:
3SO–OSO3">3SO–OSO3sup>2− 2
4">O4sup>•−
Moreover, sodium peroxydisulfate can be used for soil and
groundwater remediation
Groundwater remediation is the process that is used to treat polluted groundwater by removing the pollutants or converting them into harmless products. Groundwater is water present below the ground surface that saturates the pore space in the subs ...
, water and wastewater treatment, and etching of copper on circuit boards.
It has also been used to produce hair lighteners and bleaches, medical drugs, cellophane, rubber, soaps, detergents, adhesive papers, dyes for textiles, and in photography.
In addition to its major commercial applications, peroxydisulfate participates in reactions of interest in the laboratory:
*
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.
...
* Oxidation of Ag
+ to Ag
2+, such as the preparation of
tetrakis(pyridine)silver(II) peroxydisulfate
Structure
References
*
Sulfur oxyanions
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