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The Criegee oxidation is a glycol cleavage reaction in which vicinal diols are oxidized to form ketones and aldehydes using lead tetraacetate. It is analogous to the use of periodate (Malaprade reaction) but uses a milder oxidant. This oxidation was discovered by Rudolf Criegee and coworkers and first reported in 1931 using ethylene glycol as ...
Lead tetraacetate is a strong oxidizing agent, [6] a source of acetyloxy groups, and a general reagent for the preparation of organolead compounds. Some of its many uses in organic chemistry: Acetoxylation of benzylic, allylic, [7] and α-oxygen ether C−H bonds, for example the conversion of dioxane to 2-acetoxy-1,4-dioxane [8]
Another reagent is lead tetraacetate (Pb(OAc) 4). [4] These I- and Pb-based methods are called the Malaprade reaction and Criegee oxidation, respectively. The former is favored for aqueous solutions, the latter for nonaqueous solutions. [1] Cyclic intermediate are invariably invoked. The ring then fragments, with cleavage of the carbon–carbon ...
Lead(II) oxide is also soluble in alkali hydroxide solutions to form the corresponding plumbite salt. [2] PbO + 2 OH − + H 2 O → Pb(OH) 2− 4. Chlorination of plumbite solutions causes the formation of lead's +4 oxidation state. Pb(OH) 2− 4 + Cl 2 → PbO 2 + 2 Cl − + 2 H 2 O. Lead dioxide is representative of the +4 oxidation state ...
In extreme cases the periodate may be exchanged for lead tetraacetate which reacts in a similar manner and is soluble in organic solvents (Criegee oxidation). Periodate cleavage is often utilized in molecular biochemistry for the purposes of modifying saccharide rings, as many five- and six-membered sugars have vicinal diols. Historically it ...
Other methods for the α-hydroxylation of carbonyl compounds may employ toxic organometallic compounds (such as lead tetraacetate or osmium tetroxide). One alternative to hypervalent iodine oxidation that does not employ heavy metals is the attack of a metal enolate on dioxygen, followed by reduction of the resulting peroxide (equation ( 14 )).
In the absence of a hydrogen on the δ-carbon, or when the particular conformation of the substrate orients the ε-carbon close together, 1,6-hydrogen atom transfer is the favored process. However, these reactions tend to be an order of magnitude slower than the corresponding 1,5-hydrogen atom transfer.
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.