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 chemis ...

with the formula (NH₄)₂S₂O₈. It is a colourless (white)

salt Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quant ...

that is highly soluble in water, much more so than the related potassium salt. It is a strong

oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...

that is used as a catalyst in

polymer chemistry Polymer chemistry is a sub-discipline of chemistry that focuses on the structures of chemicals, chemical synthesis, and chemical and physical properties of polymers and macromolecules. The principles and methods used within polymer chemistry ar ...

, as an

etchant Etching is a printmaking technique in art. Etching may also refer to: * Etching (microfabrication), a process in producing microelectronics * Glass etching, a glass decoration technique * Chemical milling, or industrial etching * Photochemical ma ...

, and as a cleaning and

bleaching agent Bleach is the generic name for any chemical product that is used industrially or domestically to remove color (whitening) from a fabric or fiber or to clean or to remove stains in a process called bleaching. It often refers specifically, to ...

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 Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen a ...

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 fo ...

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 a ...

.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 Hugh Marshall FRS FRSE FCS (7 January 1868 – 5 September 1913) was a Scottish chemist who discovered persulphates in 1891. He was the inventor of Marshall's acid. In 1902 he proposed the modified sign of equality which became standard in c ...

. The ammonium, sodium, and potassium salts adopt very similar structures in the solid state, according to

X-ray crystallography X-ray crystallography is the experimental science determining the atomic and molecular structure of a crystal, in which the crystalline structure causes a beam of incident X-rays to diffract into many specific directions. By measuring the angles ...

. 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

radicals Radical may refer to: Politics and ideology Politics *Radical politics, the political intent of fundamental societal change *Radicalism (historical), the Radical Movement that began in late 18th century Britain and spread to continental Europe and ...

, APS is mainly used as a

radical initiator In chemistry, radical initiators are substances that can produce radical species under mild conditions and promote radical reactions. These substances generally possess weak bonds—bonds that have small bond dissociation energies. Radical i ...

in the

polymerization In polymer chemistry, polymerization (American English), or polymerisation (British English), is a process of reacting monomer molecules together in a chemical reaction to form polymer chains or three-dimensional networks. There are many f ...

of certain

alkene 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 ...

s. 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 st ...

and

polytetrafluoroethylene Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemo ...

. 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 con ...

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 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 primar ...

in making a

polyacrylamide Polyacrylamide (abbreviated as PAM) is a polymer with the formula (-CH2CHCONH2-). It has a linear-chain structure. PAM is highly water-absorbent, forming a soft gel when hydrated. In 2008, an estimated 750,000,000 kg were produced, mainly fo ...

gel, hence being important for

SDS-PAGE SDS-PAGE (sodium dodecyl sulfate–polyacrylamide gel electrophoresis) is a Discontinuous electrophoresis, discontinuous electrophoretic system developed by Ulrich K. Laemmli which is commonly used as a method to separate proteins with molecular m ...

and

western blot The western blot (sometimes called the protein immunoblot), or western blotting, is a widely used analytical technique in molecular biology and immunogenetics to detect specific proteins in a sample of tissue homogenate or extract. Besides detect ...

. Illustrative of its powerful oxidizing properties, ammonium persulfate is used to etch copper on

printed circuit boards A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich struc ...

as an alternative to

ferric chloride Iron(III) chloride is the inorganic compound with the formula . Also called ferric chloride, it is a common compound of iron in the +3 oxidation state. The anhydrous compound is a crystalline solid with a melting point of 307.6 °C. The col ...

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 Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J ...

. For example, in the Minisci reaction and

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. ...

Safety

Airborne dust containing ammonium persulfate may be irritating to eye,

nose A nose is a protuberance in vertebrates that houses the nostrils, or nares, which receive and expel air for respiration alongside the mouth. Behind the nose are the olfactory mucosa and the sinuses. Behind the nasal cavity, air next passe ...

throat In vertebrate anatomy, the throat is the front part of the neck, internally positioned in front of the vertebrae. It contains the pharynx and larynx. An important section of it is the epiglottis, separating the esophagus from the trachea (windpip ...

lung The lungs are the primary organs of the respiratory system in humans and most other animals, including some snails and a small number of fish. In mammals and most other vertebrates, two lungs are located near the backbone on either side of ...

and

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

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

asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...

tic 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