The
hydroxyl radical,
•OH, is the neutral form of the
hydroxide ion (OH
-). Hydroxyl radicals are highly reactive (easily becoming
hydroxyl groups) 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 H
2O
2 (suggested in 1879) and likely in
Fenton chemistry, where trace amounts of reduced transition metals catalyze peroxide-mediated oxidations of organic compounds.