Importance of Prototropic Equilibria in Free Radical Reactions in Biology and Medicine

摘要

Equilibria involving gain or loss of protons from molecules are common features in chemistry. Free radicals also exhibit prototropic equilibria, but the positions of these equilibria may be quantitatively very different from the molecules from which the radicals are derived. Proton loss or gain can have dramatic effects on the chemical reactivity of radicals, including their "natural" lifetimes or stabilities in aqueous solution, the rates of electron-transfer reactions, and pH-dependent redox properties. A short survey and a compilation of prototropic properties of radicals are useful but rather dated sources.