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The carbon–carbon bond in a vicinal diol (glycol) is cleaved and instead the two oxygen atoms become double-bonded to their respective carbon atoms. Depending on the substitution pattern in the diol, these carbonyls will be ketones and/or aldehydes. [1] Glycol cleavage is an important for determining the structures of sugars.
In organic chemistry, the Malaprade reaction or Malaprade oxidation is a glycol cleavage reaction in which a vicinal diol is oxidized by periodic acid or a periodate salt to give the corresponding carbonyl functional groups. [1] [2] The reaction was first reported by Léon Malaprade in 1928. [3] [4] Amino alcohols are also cleaved. [5]
Periodic acid (/ ˌ p ɜːr aɪ ˈ ɒ d ɪ k / per-eye-OD-ik) is the highest oxoacid of iodine, in which the iodine exists in oxidation state +7. It can exist in two forms: orthoperiodic acid, with the chemical formula H 5 IO 6 , and metaperiodic acid, which has the formula HIO 4 .
Another method is the Woodward cis-hydroxylation (cis diol) and the related Prévost reaction (anti diol), which both use iodine and the silver salt of a carboxylic acid. A route to synthesizing cis-1,2-diols using osmium tetraoxide An example of Prévost reaction used to synthesize anti diol
Two mechanisms are proposed for the Criegee oxidation, depending on the configuration of the diol. [6] [7] If the oxygen atoms of the two hydroxy groups are conformationally close enough to form a five-membered ring with the lead atom, the reaction occurs via a cyclic intermediate.
The oxidation of primary alcohols to carboxylic acids normally proceeds via the corresponding aldehyde, which is transformed via an aldehyde hydrate (gem-diol, R-CH(OH) 2) by reaction with water. Thus, the oxidation of a primary alcohol at the aldehyde level without further oxidation to the carboxylic acid is possible by performing the reaction ...
Two ketyl groups react in a coupling reaction yielding a vicinal diol with both hydroxyl groups deprotonated. Addition of water or another proton donor gives the diol. With magnesium as an electron donor, the initial reaction product is a 5-membered cyclic compound with the two oxygen atoms coordinated to the oxidized Mg 2+ ion.
LiBr reacts with NaIO 4 and acetic acid to produce lithium acetate, which can then proceed through the reaction as previously mentioned. The protocol produced high dr for the corresponding diol, depending on the oxidant chosen. The modification of the Prevost-Woodward reaction proposed by Sudalai.