Clemmensen reduction

The 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, an Danish-American chemist.^[4]

Additional recommended knowledge

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Several reviews have been published.^[5][6][7][8]

The Clemmensen reduction is particularly effective at reducing aryl-alkyl ketones.^[9][10] With aliphatic or acyclic ketones, zinc metal reduction is much more effective.^[11]

The substrate must be stable in the strongly acidic conditions of the Clemmensen reduction. Acid sensitive substrates should use the Wolff-Kishner reduction, which utilizes strongly basic conditions. As a result of Clemmensen Reduction, the carbon of the carbonyl group involved is converted from Sp² hybridisation to Sp³ hybridisation. The oxygen atom is lost in the form of one molecule of water.

References

1. ^ Clemmensen, E. Ber. 1913, 46, 1837.
2. ^ Clemmensen, E. Ber. 1914, 47, 51.
3. ^ Clemmensen, E. Ber. 1914, 47, 681.
4. ^ Biographies of Chemists, accessed 6 Feb 2007.
5. ^ Martin, E. L. Org. React. 1942, 1, 155. (Review)
6. ^ Buchanan, J. G. St. C.; Woodgate, P. D. Quart. Rev. 1969, 23, 522. (Review)
7. ^ Vedejs, E. Org. React. 1975, 22, 401. (Review)
8. ^ Yamamura, S.; Nishiyama, S. Comp. Org. Syn. 1991, 8, 309-313.(Review)
9. ^ Organic Syntheses, γ-Phenylbutyric acid, Coll. Vol. 2, p.499 (1943); Vol. 15, p.64 (1935).
10. ^ Organic Syntheses, Creosol, Coll. Vol. 4, p.203 (1963); Vol. 33, p.17 (1953).
11. ^ Organic Syntheses, Modified Clemmensen Reduction: Cholestane, Coll. Vol. 6, p.289 (1988); Vol. 53, p.86 (1973).

See also

• Haworth phenanthrene synthesis
• Wolff-Kishner reduction