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Alcohol oxidation is a collection of oxidation reactions in organic chemistry that convert alcohols to aldehydes, ketones, carboxylic acids, and esters. The reaction mainly applies to primary and secondary alcohols. Secondary alcohols form ketones, while primary alcohols form aldehydes or carboxylic acids. [1] A variety of oxidants can be used.
Babler oxidation mechanism. The reaction proceeds through the formation of a chromate ester (1) from nucleophilic attack of the chlorochromate by the allylic alcohol.The ester then undergoes a [3,3]-sigmatropic shift to create the isomeric chromate ester (2).
Allylic oxidation using selenium-dioxide proceeds via an ene reaction at the electrophilic selenium center. A 2,3-sigmatropic shift , proceeding through an envelope-like transition state , gives the allylselenite ester, which upon hydrolysis gives the allylic alcohol.
Allyl alcohols in general are prepared by allylic oxidation of allyl compounds, using selenium dioxide or organic peroxides. Other methods include carbon-carbon bond-forming reactions such as the Prins reaction, the Morita-Baylis-Hillman reaction, or a variant of the Ramberg-Bäcklund reaction. Hydrogenation of enones is another route.
The Kharasch–Sosnovsky reaction is a method that involves using a copper or cobalt salt as a catalyst to oxidize olefins at the allylic position, subsequently condensing a peroxy ester (e.g. tert-Butyl peroxybenzoate) or a peroxide resulting in the formation of allylic benzoates or alcohols via radical oxidation. [1]
The conversion of valencene to nootkatone is an example of allylic oxidation. In the synthesis of some fine chemicals, selenium dioxide is used to convert alkenes to allylic alcohols: [15] R 2 C=CR'-CHR" 2 + [O] → R 2 C=CR'-C(OH)R" 2. where R, R', R" may be alkyl or aryl substituents.
The epoxidation of allylic alcohols is a class of epoxidation reactions in organic chemistry.One implementation of this reaction is the Sharpless epoxidation.Early work showed that allylic alcohols give facial selectivity when using meta-chloroperoxybenzoic acid (m-CPBA) as an oxidant.
The Wharton olefin synthesis or the Wharton reaction is a chemical reaction that involves the reduction of α,β-epoxy ketones using hydrazine to give allylic alcohols. [1] [2] [3] This reaction, introduced in 1961 by P. S. Wharton, is an extension of the Wolff–Kishner reduction.