Semidione Explained

Semidiones are radical anions analogous to semiquinones, obtained from the one-electron reduction of non-quinone conjugated dicarbonyls.^[1] The simplest possible semidiones are derived from 1,2-dicarbonyls and have structure, making them the second member of a homologous series starting with ketyl radicals.^[1] They are often transient intermediates, appearing in reactions such as the final reduction step of the acyloin condensation.^[2]

Benzil semidione, synthesized by Auguste Laurent in 1836, is believed to have been the first radical ion ever characterized.^[3]

Semidehydroascorbate is a stable semidione produced by the one-electron oxidation of Vitamin C.

Notes and References

1. Book: Russell, Glen A.. Kevan . Larry . Kaiser . Larry Kevan . Emil T. . Emil T. Kaiser . Radical Ions . 1968 . New York Interscience . 978-0-470-45490-9 . 87–150 . Chapter 3: Semidione Radical Anions .
2. Book: Roth, Heinz D. . Moss . Robert A. . Platz . Matthew . Jones . Maitland . Maitland Jones Jr. . Reactive Intermediate Chemistry . 2004 . Wiley-Interscience . 978-0-471-23324-4 . Chapter 6: Organic Radical Ions . 260.
3. Book: Organic Chemistry . 26 . 1973 . Organic Reactive Intermediates . McManus . Samuel P. . Russell . Glen A. . Norris . Robert K. . Chapter 6: Radical Ions . 423–448 . Elsevier . 0078-611X . 10.1016/B978-0-12-485450-5.50011-7.