Clemmensen Reduction

About Clemmensen Reduction

The reduction of carbonyl groups of aldehydes and ketones to methylene groups with amalgamated zinc and concentrated hydrochloric acid is known as Clemmensen reduction.

The reduction of carbonyl groups of aldehydes and ketones to methylene groups with amalgamated zinc and concentrated hydrochloric acid is known as Clemmensen reduction.

1. The reduction consists in refluxing the carbonyl compounds with amalgamated zinc and excess of concentrated hydrochloric acid.
2. The reduction is useful especially for ketones containing phenolic or carboxylic groups which remain unaffected. Ketones are reducing more often than aldehydes.
3. This reduction is also observed in Wolff-Kishner reduction but Clemmensen reduction is easier to perform.
4. The reduction, however, fails with acid-sensitive and high molecular weight substrates. The α, β-unsaturated ketones undergo reduction of both the olefinic and carbonyl groups.

Reaction Mechanism of Clemmensen Reduction

Exceptional behaviour of clemmensen reductions

Certain cyclic 1,3-diketones give under Clemmensen reduction a fully reduced product along with a monoketone with ring contraction.

The latter probably is formed through a diradical with subsequent intramolecular C – C bond formation and pinacol type rearrangement.

List of Name Reaction of Organic Chemistry consist of detail Reaction Mechanism of all name reactions of Organic Chemistry.