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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 stress ...
In chemistry and biology, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (O 2), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (O 2 H), superoxide (O 2-), [1] hydroxyl radical (OH.), and singlet oxygen. [2] ROS are pervasive because they are readily produced from O 2, which is ...
In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. [1] [2] With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes.
Hydroxyl radicals are produced with the help of one or more primary oxidants (e.g. ozone, hydrogen peroxide, oxygen) and/or energy sources (e.g. ultraviolet light) or catalysts (e.g. titanium dioxide). Precise, pre-programmed dosages, sequences and combinations of these reagents are applied in order to obtain a maximum •OH yield.
The free radicals generated by this process engage in secondary reactions. For example, the hydroxyl is a powerful, non-selective oxidant. [6] Oxidation of an organic compound by Fenton's reagent is rapid and exothermic and results in the oxidation of contaminants to primarily carbon dioxide and water.
Termination (elementary step in which the active particle loses its activity; e. g. by recombination of two free radicals). The chain length is defined as the average number of times the propagation cycle is repeated, and equals the overall reaction rate divided by the initiation rate. [1]
Ultimately, both reactions generate hydroxyl radicals. These radicals are oxidative in nature and nonselective with a redox potential of E 0 = +3.06 V. [24] This is significantly greater than many common organic compounds, which typically are not greater than E 0 = +2.00 V. [25] This results in the non-selective oxidative behavior of these ...
This reaction has long been studied and revived in different contexts, including organic chemistry, free radicals, radiochemistry, and water radiolysis. In the 1970, with the emerging interest for the effect of free radicals onto the ageing mechanisms of living cells due to oxygen (O 2 ), it was proposed that the Haber–Weiss reaction was a ...