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The Blaise ketone synthesis (named after Edmond Blaise) is the
After the oxygen forms a bond with the organozinc compound, R’ shifts to the carbonyl carbon, having chlorine act as a leaving group and removing the negative charge from zinc. The chlorine that left returns to form a bond with zinc, pushing the electrons back on to oxygen and thus forming the ketone.
chemical reaction
A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...
of acid chloride
In organic chemistry, an acyl chloride (or acid chloride) is an organic compound with the functional group . Their formula is usually written , where R is a side chain. They are reactive derivatives of carboxylic acids (). A specific example o ...
s with organozinc compound
Organozinc chemistry is the study of the physical properties, synthesis, and reactions of organozinc compounds, which are organometallic compounds that contain carbon (C) to zinc (Zn) chemical bonds.The Chemistry of Organozinc Compounds' (Patai S ...
s to give ketone
In organic chemistry, a ketone is an organic compound with the structure , where R and R' can be a variety of carbon-containing substituents. Ketones contain a carbonyl group (a carbon-oxygen double bond C=O). The simplest ketone is acetone ( ...
s.
The reaction was claimed to bring excellent yields by Blaise, however, investigators failed to obtain better than moderate yields (50%). Thus, the reaction is particularly ineffective in forming ketones from acyl chlorides. The reaction also works with organocuprates. Reviews have been written.
Reaction mechanism
The mechanism is sampled from the proposed mechanism fororganocadmium compound
Organocadmium chemistry describes the physical properties, synthesis, reactions, and use of organocadmium compounds, which are organometallic compounds containing a carbon to cadmium chemical bond. Cadmium shares group 12 with zinc and mercury an ...
s, given that the mechanisms are identical to one another the proposed mechanism for the reaction is the same as the one for organocadmium compounds.
After the oxygen forms a bond with the organozinc compound, R’ shifts to the carbonyl carbon, having chlorine act as a leaving group and removing the negative charge from zinc. The chlorine that left returns to form a bond with zinc, pushing the electrons back on to oxygen and thus forming the ketone.
Variations
Blaise-Maire reaction
The Blaise-Maire reaction is the Blaise ketone synthesis using β-hydroxy acid chlorides to give β-hydroxyketones, which are converted into α,β-unsaturated ketones usingsulfuric acid
Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...
.
Ketone formation from organocadmium compounds
This ketone formation is an identical reaction to the Blaise ketone synthesis. Only instead of organozinc compounds, organocadmium compounds are used and produce higher yields.See also
*Blaise reaction
The Blaise reaction is an organic reaction that forms a β-ketoester from the reaction of zinc metal with an α-bromoester and a nitrile. The reaction was first reported by Edmond Blaise (1872–1939) in 1901. The final intermediate is a metaloimi ...
*Negishi coupling
The Negishi coupling is a widely employed transition metal catalyzed cross-coupling reaction. The reaction couples organic halides or triflates with organozinc compounds, forming carbon–carbon bonds (C–C) in the process. A palladium (0) s ...
References
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