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Biology LibreTexts

A. The Chemistry of Dioxygen

Skills to Develop

  • explain why oxidation reactions with ground state dioxygen have a high enough activation energy to make the reactions, although thermodynamically favored, kinetically slow
  • explain, using molecular orbital diagrams the difference between triplet and singlet dioxygen
  • using molecular orbital diagrams and Lewis structures, describe the chemical properties of the reduction products of dioxygen (superoxide, peroxide, and water)
  • explain the ways that biological systems use to enhance dioxygen activity and reduce the effects of reactive oxygen species (ROS) such as superoxide and peroxide
  • write chemical reactions and mechanisms when appropriate for some reactions of triplet and singlet dioxygen, superoxide, peroxide and the hydroxy free radical
  • describe typical reaction of ROS with lipids, proteins, and nucleic acids and data to support the involvement of ROS in complex diseases and aging.
  • Briefly contrast the production and biological activities of ROS and reactive nitrogen intermediates (RNIs)

Oxygen may be considered one of the most important elements in chemistry. Not counting hydrocarbons, there is a greater diversity of molecules with oxygen than with carbon. Given its role in the molecular world, very little time is spent on the chemistry of oxygen in undergraduate chemistry classes. Why is oxygen so special?