Criegee glycol oxidation

What is Criegee glycol oxidation?

The Criegee glycol oxidation, also known as Criegee oxidation, was initially discovered by Criegee in 1931. This oxidation involves the use of lead tetraacetate Pb(OAc)4, LTA to oxidize 1,2-diols (or glycols) to aldehydes or ketones by breaking the C-C bond between the hydroxyl-carrying carbon atoms.

Criegee Glycol oxidation - Criegee oxidation - general reaction scheme
Criegee glycol oxidation

R1, R2, R3, R4 = H, alkyl, aryl (see list of acronyms)

This process occurs almost entirely at room temperature and is highly dependent on the glycol’s structure and solvent. Originally, it was believed that this reaction could only take place in anhydrous organic solvents, which led to significant effort being put into solvent drying. However, it has since been demonstrated that this reaction can occur in solvents with moisture or even in aqueous solutions if the oxidation rate is faster than the hydrolysis rate of lead tetraacetate. For example, monosaccharides like glucose and mannose can undergo oxidation in aqueous solutions. Additionally, lead tetraacetate can oxidize not only 1,2-diols but also α-amino alcohols, 5α-hydroxyl carbonyl compounds, and α-keto acids.

The oxidation rate is affected by the diol’s configuration and conformation, with cis-diol oxidation being faster than trans-diol oxidation. Specifically, cis-diol that forms a five-membered ring structure has the fastest oxidation rate.

During sugar oxidation, glucose, glycerol, mannitol, and xylose are easily oxidized in aqueous solution, while sucrose cannot be oxidized under similar conditions. Interestingly, the oxidation of α-hydroxyl tertiary amines is different from that of primary or secondary α-hydroxyl amines, with the former yielding a secondary amine and an aldehyde through C-N bond cleavage, while the latter involves C-C bond cleavage.

The Criegee glycol oxidation is similar to the Malaprade reaction, which involves the oxidation of diols using periodate in aqueous solution. However, extensive periodate oxidation of 1,2,3-triols results in only aldehydes or ketones and formic acid. Excess lead tetraacetate oxidation produces aldehydes or ketones and carbon dioxide from the middle hydroxyl group. The decomposition of lead tetraacetate occurs through an ionic mechanism.

Other oxidations using lead tetraacetate Pb(OAc)include alcohol oxidation (to ketones), conjugated diene oxidation (to esters of cis– or trans-glycol), olefin oxidation (to glycol acetate or allylic acetate), cyclooctanol oxidation (to ether-containing tetrahydrofuran rings), thioether oxidation (to sulfone), and amine oxidation.

The application of this reaction extends to the analysis of carbohydrate structures and the breaking down of neighboring diols, α-keto alcohols, α-keto acids, and hydroxyamines. Additionally, this oxidation can be utilized as a means of preparing aldehydes and ketones.

References

Criegee, R. (1931), Eine oxydative Spaltung von Glykolen (II. Mitteil. über Oxydationen mit Blei(IV)-salzen). [An oxidative cleavage of glycols (II. note on oxidations with lead(IV) salts).] Ber. Dtsch. Chem. Ges. A/B, 64: 260-266. https://doi.org/10.1002/cber.19310640212

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