Bouveault-Blanc reduction

Theory and Defination :

The reduction of esters into alcohols with sodium in ethanol, in which sodium serves as a single electron reducing agent and ethanol is the proton donor, is generally known as the Bouveault–Blanc reduction. Other alcohols have also been applied as proton donors. In the absence of proton donor, the reduction of esters with sodium leads to the formation of acyloins. It has also been pointed out that the Bouveault–Blanc reduction under appropriate conditions effects the ring reduction of aromatic compounds. This reaction is an inexpensive substitute for lithium aluminum hydride reductions of esters in industrial production before the development of the metal hydride. It has been proved in the present study that the ketyl radical can cyclize to form cyclic or Spiro cyclic molecules if a double bond exists in the appropriate location of the ester.

The Bouveault–Blanc reduction is a chemical reaction in which an ester is reduced to primary alcohols using absolute ethanol and sodium metal.

General Reaction :

This reaction is an inexpensive and large-scale alternative to lithium aluminium hydride reduction of esters.

Mechanism:

Sodium metal is a single-electron reducing agent, meaning the sodium metal will transfer electrons one at a time. Four sodium atoms are required to fully reduce each ester to alcohols. Ethanol serves as a proton source.

Example & Applications :

1) Sodium Dispersion Reagent for the Bouveault-Blanc Reduction of Esters

2) Sodium in silica gel (Na-SG) - a safe, free-flowing powder - has been used for the Bouveault-Blanc reduction of various aliphatic esters. Primary alcohols were prepared in excellent yield under mild reaction conditions.