Hydroxyl radical

hydroxyl radicalsOHhydroxylOH radical•OH • OHAtmospheric -OH rate constanthydroxy radical, OHhydroxyl (OH)hydroxyl radicals ( . OH)
The hydroxyl radical, • OH, is the neutral form of the hydroxide ion (OH − ).wikipedia
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Hydroxide

OHhydroxide ionOH −
The hydroxyl radical, • OH, is the neutral form of the hydroxide ion (OH − ).
The corresponding electrically neutral compound HO • is the hydroxyl radical.

Radical (chemistry)

free radicalradicalfree radicals
Hydroxyl radicals are highly reactive (easily becoming hydroxyl groups) and consequently short-lived; however, they form an important part of radical chemistry.
A notable example of a radical is the hydroxyl radical (HO•), a molecule that has one unpaired electron on the oxygen atom.

Hydroxy group

hydroxylhydroxyl grouphydroxy
Hydroxyl radicals are highly reactive (easily becoming hydroxyl groups) and consequently short-lived; however, they form an important part of radical chemistry.
Both the negatively charged anion OH −, called hydroxide, and the neutral radical • OH, known as the hydroxyl radical, consist of an unbounded hydroxyl group.

Hydrogen peroxide

H 2 O 2 H2O2HO
It is also an important radical formed in radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments.
Certain metal ions, such as or, can cause the decomposition to take a different path, with free radicals such as the hydroxyl radical (HO·) and hydroperoxyl (HOO·) being formed.

Fenton's reagent

Fenton reactionFenton chemistryFenton
Hydroxyl radicals are also produced during UV-light dissociation of H 2 O 2 (suggested in 1879) and likely in Fenton chemistry, where trace amounts of reduced transition metals catalyze peroxide-mediated oxidations of organic compounds.
Iron(II) is oxidized by hydrogen peroxide to iron(III), forming a hydroxyl radical and a hydroxide ion in the process.

Greenhouse gas

greenhouse gasescarbon emissionsgreenhouse gas emissions
It also has an important role in eliminating some greenhouse gases like methane and ozone.
The main chemical that reacts with methane in the atmosphere is the hydroxyl radical (OH), thus more methane means that the concentration of OH goes down.

Ozone

ozonationO 3 ozone generator
It also has an important role in eliminating some greenhouse gases like methane and ozone.
Ozone photolysis by UV light leads to production of the hydroxyl radical HO• and this plays a part in the removal of hydrocarbons from the air, but is also the first step in the creation of components of smog such as peroxyacyl nitrates, which can be powerful eye irritants.

Photodissociation

photolysisphotodecompositionphotolytic
In organic synthesis, hydroxyl radicals are most commonly generated by photolysis of 1-hydroxy-2(1H)-pyridinethione.
which generates an excited oxygen atom which can react with water to give the hydroxyl radical:

Pyrithione

1-hydroxy-2(1''H'')-pyridinethione
In organic synthesis, hydroxyl radicals are most commonly generated by photolysis of 1-hydroxy-2(1H)-pyridinethione.
Pyrithione can be used as a source of hydroxyl radical in organic synthesis as it photochemically decomposes to HO • and (pyridin-2-yl)sulfanyl radical.

Lipid peroxidation

lipid oxidationperoxidationlipid peroxides
The hydroxyl radical can damage virtually all types of macromolecules: carbohydrates, nucleic acids (mutations), lipids (lipid peroxidation), and amino acids (e.g. conversion of Phe to m-Tyrosine and o-Tyrosine).
The most notable initiators in living cells are reactive oxygen species (ROS), such as OH· and HOO·, which combines with a hydrogen atom to make water and a fatty acid radical.

Advanced oxidation process

advanced oxidationadvanced oxidation process (AOP)advanced oxidation processes
Hydroxyl radicals play a key role in the oxidative destruction of organic pollutant using a series of methodologies collectively known as advanced oxidation processes (AOPs).
Advanced oxidation processes (abbreviation: AOPs), in a broad sense, are a set of chemical treatment procedures designed to remove organic (and sometimes inorganic) materials in water and wastewater by oxidation through reactions with hydroxyl radicals (·OH).

Hydrogen cycle

hydrogen
Another major sink of free atmospheric H 2 is photochemical oxidation by hydroxyl radicals (•OH), which forms water.

Astrophysical maser

masermasersmaser emission
• OH masers, a type of astrophysical maser, were the first masers to be discovered in space and have been observed in more environments than any other type of maser.

Maser

masersAmmonia maserhydrogen maser
• OH masers, a type of astrophysical maser, were the first masers to be discovered in space and have been observed in more environments than any other type of maser.
Such emission is observed from molecules such as water (H 2 O), hydroxyl radicals (•OH), methanol (CH 3 OH), formaldehyde (HCHO), and silicon monoxide (SiO).

Organic peroxide

peroxidehydroperoxidesendoperoxide
Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water.

Atmospheric chemistry

atmospheric chemistatmospheric oxygenatmospheric composition
Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water.

Excited state

excitationexcitedexcitations
Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water.

Allotropes of oxygen

dioxygenmolecular oxygenatomic oxygen
Most notably hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water.

Oxygen

OO 2 molecular oxygen
It is also an important radical formed in radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments.

Corrosion

corrosion resistancecorrodecorrosive
It is also an important radical formed in radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments.

Stress corrosion cracking

stress corrosionstress-corrosion crackingenvironmentally-assisted cracking
It is also an important radical formed in radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments.

Organic synthesis

synthesissynthesizedsynthetic
In organic synthesis, hydroxyl radicals are most commonly generated by photolysis of 1-hydroxy-2(1H)-pyridinethione.

Troposphere

troposphericdivergencemid-tropospheric
The hydroxyl radical is often referred to as the "detergent" of the troposphere because it reacts with many pollutants, decomposing them through "cracking", often acting as the first step to their removal.

Cracking (chemistry)

crackinghydrocrackingthermal cracking
The hydroxyl radical is often referred to as the "detergent" of the troposphere because it reacts with many pollutants, decomposing them through "cracking", often acting as the first step to their removal.

Methane

methane gasCH 4 liquid methane
It also has an important role in eliminating some greenhouse gases like methane and ozone.