Kornblum-Oxidation

As Kornblum oxidation is known in chemistry, the conversion of alkyl halides ( bromides, iodides ) in the respective aldehydes bzw.Ketone by simple heating in dimethyl sulfoxide ( DMSO) with the addition of a base such as triethylamine. The reaction for the conversion of α - halogenated carbonyl compounds can be used in the respective α - oxo compounds. DMSO is used herein both as a solvent and as an oxidizing agent, and is itself reduced to the malodorous dimethylsulfide.

Overview reaction

The oxidation of Alkyhalogeniden [Example: benzyl halide (X = Br or I) ] gives carbonyl (for example benzaldehyde )

In the oxidation of α - halogenated (X = Br or I), carbonyl compounds ( R1, R2 = hydrogen atom or Organylgruppe such as alkyl or aryl group ) are produced α, β -dicarbonyl compounds:

The Kornblum oxidation is closely related to the Swern oxidation.

Mechanism

Oxidation of Alkyhalogeniden

In the first step Alkyholgenid undergoes a SN2 reaction with the nucleophilic oxygen of the dimethyl sulfoxide ( DMSO). In this case, the halide is from (X = Cl, Br, I) and produces a Alkoxysulfoniumsalz which (in this case, triethylamine) in the next step of a base is deprotonated. Then cleavage of dimethylsulphide in the formation of the respective aldehyde or ketone.

Oxidation of α - halogenated carbonyl compounds

In the first step of the nucleophilic oxygen of the dimethyl sulfoxide ( DMSO) attacks the α - carbon atom. This process proceeds via an SN2 reaction, the halide ( X = Cl, Br, I) is cleaved. This produces a Alkoxysulfoniumsalz which, in contrast to the oxidation of Alkyhalogeniden now not at the methyl group but also the α - carbon atom of a base (in this case triethylamine) is deprotonated. In the last step, then it comes with the elimination of dimethyl sulfide to form the corresponding α -oxo carbonyl compound.