The Bouveault–Blanc reduction is a
chemical reaction
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breakin ...
in which an
ester is
reduced to
primary alcohol
A primary alcohol is an alcohol in which the hydroxy group is bonded to a primary carbon atom. It can also be defined as a molecule containing a “–CH2OH” group.
In contrast, a secondary alcohol has a formula “–CHROH” and a tertiary ...
s using
absolute ethanol and
sodium metal.
It was first reported by
Louis Bouveault and Gustave Louis Blanc in 1903. Bouveault and Blanc demonstrated the reduction of
ethyl oleate
Ethyl oleate is a fatty acid ester formed by the condensation of oleic acid and ethanol. It is a colorless oil although degraded samples can appear yellow.
Use and occurrence Additive
Ethyl oleate is used by compounding pharmacies as a vehicle f ...
and ''n''-butyl oleate to
oleyl alcohol. modified versions of which were subsequently refined and published in ''
Organic Syntheses
''Organic Syntheses'' is a peer-reviewed scientific journal that was established in 1921. It publishes detailed and checked procedures for the synthesis of organic compounds. A unique feature of the review process is that all of the data and exp ...
''.
:
This reaction is used commercially although for laboratory scale reactions it was made obsolete by the introduction of
lithium aluminium hydride.
Reaction mechanism
Sodium metal is a one-electron reducing agent. Four equivalents of sodium are required to fully reduce each ester.
Ethanol serves as a proton source.
The reaction produces sodium
alkoxides, according to the following stoichiometry:
: + 6 Na + 4 → + + 4
In practice, considerable sodium is consumed by the formation of hydrogen. For this reason, an excess of sodium is often required. Because the hydrolysis of sodium is rapid, not to mention dangerous, the Bouveault-Blanc reaction requires anhydrous ethanol.
[ The mechanism of the reaction follows:]silica gel
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other ...
, which has a safety and yield profile similar to that of hydride reagents. Another modification uses a sodium dispersion.
See also
* Acyloin condensation – The reductive coupling of esters, using sodium, to yield an α-hydroxyketone
* Akabori amino-acid reaction – The reduction of amino acid esters, by sodium, to yield aldehydes
*Birch reduction
The Birch reduction is an organic reaction that is used to convert arenes to cyclohexadienes. The reaction is named after the Australian chemist Arthur Birch and involves the organic reduction of aromatic rings in an amine solvent (traditionally ...
– For the reduction of alkenes using sodium
* Bouveault aldehyde synthesis – Another organometallic reaction by Bouveault where a Grignard reagent is converted to an aldehyde
References
External links
Animation of the Bouveault–Blanc reduction
{{DEFAULTSORT:Bouveault-Blanc reduction
Free radical reactions
Organic redox reactions
Name reactions