Thermodynamic considerations on the generation of hydroxyl radicals from nitrous oxide--no laughing matter.

The one-electron reduction of nitrous oxide is a possible pathway to the hydroxyl radical. The one- and two-electron reduction potentials EO' (N2O/OH,N2) and EO' (N2O/H2O, N2) are calculated to be 0.32 V and 1.32 V at pH 7, respectively, for all species dissolved in water. Although nitrous oxide is thermodynamically capable of oxidising a variety of biomolecules, it is kinetically rather inert. The reason that nitrous oxide does not produce hydroxyl radicals readily might be that the one-electron reduction proceeds through an N2O- intermediate which is energetically very unfavourable: EO (N2O/N2O-) = -1.1 V.