Ammonium persulfate (APS) is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemist ...

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 catalyst in polymer chemistry, as an

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, and as a cleaning and

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Preparation and structure

Ammonium persulfate is prepared by

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...

of a cold concentrated solution of either ammonium sulfate or ammonium bisulfate in

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid ( Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen and hydrogen, with the molecular formu ...

at a high

current density In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional ar ...

.F. Feher, "Potassium Peroxydisulfate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 390. The method was first described by Hugh Marshall. The ammonium, sodium, and potassium salts adopt very similar structures in the solid state, according to X-ray crystallography. In the ammonium salt, the O-O distance is 1.497Å. The sulfate groups are tetrahedral, with three short S-O distances near 1.44Å and one long S-O bond at 1.64Å.

Uses

As a source of

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, APS is mainly used as a radical initiator in the polymerization of certain alkenes. Commercially important polymers prepared using persulfates include

styrene-butadiene rubber Styrene-butadiene or styrene-butadiene rubber (SBR) describe families of synthetic rubbers derived from styrene and butadiene (the version developed by Goodyear is called Neolite). These materials have good abrasion resistance and good aging s ...

and

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. In solution, the

dianion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conven ...

dissociates into radicals: : ₃SO–OSO₃sup>2− 2 O₄sup>•− Regarding its mechanism of action, the sulfate radical adds to the alkene to give a

sulfate ester Organosulfates are a class of organic compounds sharing a common functional group with the structure R-O-SO3−. The SO4 core is a sulfate group and the R group is any organic residue. All organosulfates are formally esters derived from alcohols ...

radical. It is also used along with tetramethylethylenediamine to catalyze the polymerization of

acrylamide Acrylamide (or acrylic amide) is an organic compound with the chemical formula CH2=CHC(O)NH2. It is a white odorless solid, soluble in water and several organic solvents. From the chemistry perspective, acrylamide is a vinyl-substituted primary ...

in making a polyacrylamide gel, hence being important for SDS-PAGE and western blot. Illustrative of its powerful oxidizing properties, ammonium persulfate is used to etch copper on printed circuit boards as an alternative to ferric chloride solution. This property was discovered many years ago. In 1908, John William Turrentine used a dilute ammonium persulfate solution to etch copper. Turrentine weighed copper spirals before placing the copper spirals into the ammonium persulfate solution for an hour. After an hour, the spirals were weighed again and the amount of copper dissolved by ammonium persulfate was recorded. This experiment was extended to other metals such as nickel, cadmium, and iron, all of which yielded similar results. The oxidation equation is thus: (aq) + 2 → 2 (aq). Ammonium persulfate is a standard ingredient in

hair bleach Hair bleaching, is the practice of lightening the hair color mainly for cosmetic purposes using bleaching agents. Bleaching can be done alone, combined with a toner, or as a step for further hair coloring. The most common commercial bleaching age ...

. Persulfates are used as oxidants in organic chemistry. For example, in the

Minisci reaction The Minisci reaction () is a named reaction in organic chemistry. It is a nucleophilic radical substitution to an electron deficient aromatic compound, most commonly the introduction of an alkyl group to a nitrogen containing Heterocyclic compound, ...

and Elbs persulfate oxidation

Safety

Airborne dust containing ammonium persulfate may be irritating to

eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and conv ...

, nose, throat,

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and skin upon contact. Exposure to high levels of dust may cause difficulty in breathing. It has been noted that persulfate salts are a major cause of asthmatic effects. Furthermore, it has been suggested that exposure to ammonium persulfate can cause asthmatic effects in hair dressers and receptionists working in the hairdressing industry. These asthmatic effects are proposed to be caused by the oxidation of cysteine residues, as well as methionine residues.

References

External links

International Chemical Safety Card 0632
{{Ammonium salts Persulfates Peroxides Ammonium compounds Oxidizing agents