Clemmensen reduction

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Clemmensen reduction is a chemical reaction described as a reduction of ketones (or aldehydes) to alkanes using zinc amalgam and hydrochloric acid.[1][2][3] This reaction is named after Erik Christian Clemmensen, a Danish chemist.[4]

The Clemmensen reduction is particularly effective at reducing aryl-alkyl ketones,[5][6] such as those formed in a Friedel-Crafts acylation. With aliphatic or cyclic ketones, zinc metal reduction is much more effective.[7]

The substrate must be stable in the strongly acidic conditions of the Clemmensen reduction. Acid sensitive substrates should be reacted in the Wolff-Kishner reduction, which utilizes strongly basic conditions; a further, milder method is the Mozingo reduction. The oxygen atom is lost in the form of one molecule of water.

References

  1. ↑ Clemmensen, E. (1913). Chemische Berichte 46: 1837. 
  2. ↑ Clemmensen, E. (1914). Chemische Berichte 47: 51. 
  3. ↑ Clemmensen, E. (1914). Chemische Berichte 47: 681. 
  4. ↑ Biographies of Chemists, accessed 6 Feb 2007
  5. ↑ "γ-Phenylbutyric acid", Org. Synth. 2, 1943: 499 ; Vol. 15, p.64 (1935)
  6. ↑ "Creosol", Org. Synth. 4, 1963: 203 ; Vol. 33, p.17 (1953).
  7. ↑ "Modified Clemmensen Reduction: Cholestane", Org. Synth. 6, 1988: 289 ; Vol. 53, p.86 (1973).

Reviews

  • Martin, E. L. (1942). Org. React. 1: 155. 
  • Buchanan, J. G. St. C.; Woodgate, P. D. (1969). "The Clemmensen reduction of difunctional ketones". Quart. Rev. 23: 522. doi:10.1039/QR9692300522. 
  • Vedejs, E. (1975). Org. React. 22: 40. 
  • Yamamura, S.; Nishiyama, S. (1991). Comp. Org. Syn. 8: 309–313. 

See also

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