This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Hydroxyl radical" – news · newspapers · books · scholar · JSTOR(May 2010) (Learn how and when to remove this message)
Neutral form of the hydroxide ion (OH−)
Hydroxyl radical
Names
IUPAC name
Hydroxyl radical
Systematic IUPAC name
Oxidanyl[1] (substitutive)
Hydridooxygen(•)[1] (additive)
Other names
Hydroxy
Hydroxyl
λ1-Oxidanyl
Identifiers
CAS Number
3352-57-6
3D model (JSmol)
Interactive image
ChEBI
CHEBI:29191
ChemSpider
138477Y
Gmelin Reference
105
KEGG
C16844Y
PubChem CID
157350
InChI
InChI=1S/HO/h1HY
Key: TUJKJAMUKRIRHC-UHFFFAOYSA-NY
SMILES
[OH]
Properties
Chemical formula
HO
Molar mass
17.007 g·mol−1
Thermochemistry
Std molar entropy (S⦵298)
183.71 J K−1 mol−1
Std enthalpy of formation (ΔfH⦵298)
38.99 kJ mol−1
Related compounds
Related compounds
O2H+ OH− O22−
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
Chemical compound
Skeletal formulae of 1-hydroxy-2(1H)-pyridinethione and its tautomer
The hydroxyl radical, •HO, is the neutral form of the hydroxide ion (HO–). Hydroxyl radicals are highly reactive and consequently short-lived; however, they form an important part of radical chemistry. 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. 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. Hydroxyl radicals are also produced during UV-light dissociation of H2O2 (suggested in 1879) and likely in Fenton chemistry, where trace amounts of reduced transition metals catalyze peroxide-mediated oxidations of organic compounds.
In organic synthesis hydroxyl radicals are most commonly generated by photolysis of 1-Hydroxy-2(1H)-pyridinethione.
The hydroxyl radical is often referred to as the "detergent" of the troposphere because it reacts with many pollutants, often acting as the first step to their removal. It also has an important role in eliminating some greenhouse gases like methane and ozone.[2] The rate of reaction with the hydroxyl radical often determines how long many pollutants last in the atmosphere, if they do not undergo photolysis or are rained out. For instance, methane, which reacts relatively slowly with hydroxyl radical, has an average lifetime of >5 years and many CFCs have lifetimes of 50+ years. Pollutants, such as larger hydrocarbons, can have very short average lifetimes of less than a few hours.
The first reaction with many volatile organic compounds (VOCs) is the removal of a hydrogen atom, forming water and an alkyl radical (R•).
•HO + RH → H2O + R•
The alkyl radical will typically react rapidly with oxygen forming a peroxy radical.
R• + O2 → RO2
The fate of this radical in the troposphere is dependent on factors such as the amount of sunlight, pollution in the atmosphere and the nature of the alkyl radical that formed it (See chapters 12 & 13 in External Links "University Lecture notes on Atmospheric chemistry)
^ ab"Hydroxyl (CHEBI:29191)". Chemical Entities of Biological Interest (ChEBI). UK: European Bioinformatics Institute.
^Forster, P.; V. Ramaswamy; P. Artaxo; T. Berntsen; R. Betts; D.W. Fahey; J. Haywood; J. Lean; D.C. Lowe; G. Myhre; J. Nganga; R. Prinn; G. Raga; M. Schulz; R. Van Dorland (2007). "Changes in Atmospheric Constituents and in Radiative Forcing" (PDF). In Solomon, S.; D. Qin; M. Manning; Z. Chen; M. Marquis; K.B. Averyt; M.Tignor; H.L. Miller (eds.). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press. The hydroxyl free radical (OH) is the major oxidizing chemical in the atmosphere, destroying about 3.7 Gt of trace gases, including CH4 and all HFCs and HCFCs, each year (Ehhalt, 1999).
The hydroxylradical, •HO, is the neutral form of the hydroxide ion (HO–). Hydroxylradicals are highly reactive and consequently short-lived; however...
neutral radical HO·, known as the hydroxylradical, consist of an unbonded hydroxy group. According to IUPAC definitions, the term hydroxyl refers to...
relatively stable precursors to hydroxylradicals. 60%–70% of cellular DNA damage is caused by hydroxylradicals, yet hydroxylradicals are so reactive that they...
chemical. The corresponding electrically neutral compound HO• is the hydroxylradical. The corresponding covalently bound group –OH of atoms is the hydroxy...
propagation, and termination. In the initiation phase, a pro-oxidant hydroxylradical (OH•) abstracts the hydrogen at the allylic position (–CH2–CH=CH2)...
oxidative potential of the positive holes oxidizes water to create hydroxylradicals. It can also oxidize oxygen or organic materials directly. Hence,...
with hydroxylradical (•OH) to produce a radical intermediate •HOCO, which transfers rapidly its radical hydrogen to O2 to form peroxy radical (HO2•)...
peroxide. Some prominent ROS are hydroperoxide (O2H), superoxide (O2-), hydroxylradical (OH.), and singlet oxygen. ROS are pervasive because they are readily...
hypochlorous acid (HClO), and free radicals such as the hydroxylradical (·OH), and the superoxide anion (O2−). The hydroxylradical is particularly unstable and...
the reactive oxygen species generated, e.g., O2− (superoxide radical), OH (hydroxylradical) and H2O2 (hydrogen peroxide). Further, some reactive oxidative...
(CH−3), methylium cation (CH+3) or methyl radical (CH• 3). The anion has eight valence electrons, the radical seven and the cation six. All three forms...
CH• 3 It can also be produced by the reaction of methane with the hydroxylradical: OH• + CH4 → CH• 3 + H2O This process begins the major removal mechanism...
generates hydroxylradicals through Fenton chemistry. The hydroxylradicals can then react with the nucleic acid molecules. Hydroxylradicals attack the...
the air for up to a week. It decomposes by reacting with oxygen and hydroxylradical to form formyl cyanide and formaldehyde. Acrylonitrile is harmful to...
major factor implicated in the free-radical theory of aging, based on its ready conversion into a hydroxylradical. Eggs of sea urchin, shortly after fertilization...
byproduct of the oxidation of carbon monoxide and of hydrocarbons by the hydroxylradical. Because dielectric constant has a strong effect on pKa, and the dielectric...
HS• is formed in the Earth's atmosphere by the reaction of HO•, the hydroxylradical, on carbon disulfide, carbon oxysulfide and hydrogen sulfide with side...
vocalist OH, the hydroxy functional group OH−, hydroxide anion •OH, hydroxylradical OH, the alcohol class of compounds, that possess a hydroxy functional...
formation of hydroxylradicals (·OH) through ozone photolysis. Since the major sink of methane in the atmosphere is by reaction with •OH radicals, the NOx...
reacts with the hydroperoxyl radical (HO• 2) to form nitrogen dioxide (NO2), which then can react with a hydroxylradical (•OH) to produce nitric acid...
shared qualities with both ethyl alcohol (with one hydroxyl group) and glycerin (with three hydroxyl groups). In 1859, Wurtz prepared ethylene glycol via...
intermediates that include the superoxide radical (O2−) and the hydroxylradical (OH•), as well as the non-radical species hydrogen peroxide (H2O2). These...
Global Information
