Étard reaction

Etard the reaction is an organic chemical reaction in which a methylene group is directly bonded to an aryl or heteroaryl radical, with chromium ( VI) is oxidized to formyl oxiddichlorid an aldehyde.

The names of reaction is named after its discoverer, the French chemist Alexandre Léon ETARD (1852 - 1910).

Overview reaction

By this reaction, for example, toluene can be oxidized to benzaldehyde:

The response time of the ETARD reaction is usually a few days or even weeks, the yields obtained are often very high.

Reaction mechanism

The reaction mechanism includes an ene reaction with chromium ( VI) oxiddichlorid wherein Etard a complex precipitates. The ETARD complex then decays by a [2,3 ] - sigmatropic rearrangement under reducing conditions (aqueous sodium sulfite solution ) to suppress the undesired further oxidation to a carboxylic acid. Typical solvents for the reaction are Etard carbon disulfide, chloroform, or carbon tetrachloride. For the recovery of highly pure aldehydes of ETARD complex is cleaned often.

Limits of applicability

Etard the reaction is used to oxidise toluene to benzaldehyde. The oxidation of other alkyl-substituted aryls is sometimes disturbed by rearrangement reactions. This results in the oxidation of n- propylbenzene, propiophenone, benzyl methyl ketone and some chlorinated products.

Other oxidizing agents such as potassium permanganate or potassium dichromate oxidation of alkyl-substituted aryls to carboxylic acids, aldehydes not, as in the Etard reaction.