2.[1] The systematic name of the anion is dioxide(1−). The reactive oxygen ion superoxide is particularly important as the product of the one-electron reduction of dioxygen O2, which occurs widely in nature.[2] Molecular oxygen (dioxygen) is a diradicalcontaining two unpaired electrons, and superoxide results from the addition of an electron which fills one of the two degenerate molecular orbitals, leaving a charged ionic species with a single unpaired electron and a net negative charge of −1. Both dioxygen and the superoxide anion are free radicals that exhibit paramagnetism.[3]
Because superoxide is toxic at high concentrations, nearly all organisms living in the presence of oxygen express SOD. SOD efficiently catalyzes the disproportionation of superoxide:
- 2 HO2 → O2 + H2O2
Other proteins that can be both oxidized and reduced by superoxide (e.g., hemoglobin) have weak SOD-like activity. Genetic inactivation ("knockout") of SOD produces deleterious phenotypes in organisms ranging from bacteria to mice and have provided important clues as to the mechanisms of toxicity of superoxide in vivo.
https://en.wikipedia.org/wiki/Superoxide
A polar aprotic solvent is a solvent that lacks an acidic proton and is polar. Such solvents lack hydroxyl and amine groups. These solvents do not serve as proton donors in hydrogen bonding, although they can be proton acceptors. Many solvents, including chlorocarbons and hydrocarbons, are classifiable as aprotic, but polar aprotic solvents are of particular interest for their ability to dissolve salts.
https://en.wikipedia.org/wiki/Polar_aprotic_solvents
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