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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(IV) acetate or lead tetraacetate is an metalorganic compound with chemical formula Pb(C 2 H 3 O 2) 4. It is a colorless solid that is soluble in nonpolar, organic solvents, indicating that it is not a salt. It is degraded by moisture and is typically stored with additional acetic acid. The compound is used in organic synthesis. [2]
This lack of tight radical pairing is also supported by the observation that alkyl radicals generated by Barton conditions can undergo radical cyclization while analogous intermediates generated by lead tetraacetate oxidation do not. [13] In rare cases, it appears that the alkoxyl radical may epimerize before hydrogen atom abstraction. [14]
It was also observed, that the addition of lead tetraacetate can facilitate the Stieglitz rearrangement of amine derivatives. [32] After the formation of the activated amine derivative intermediate by coordination to the lead center, the following rearrangement again proceeds via migration of the aromatic group under formation of a C–N bond ...
In the binuclear ion [Co 2 (OH 2) 10] 4+ each bridging water molecule donates one pair of electrons to one cobalt ion and another pair to the other cobalt ion. The Co-O (bridging) bond lengths are 213 picometers, and the Co-O (terminal) bond lengths are 10 pm shorter.
Tarnished lead (left) and shiny lead (right) Compounds of lead exist with lead in two main oxidation states: +2 and +4. The former is more common. Inorganic lead(IV) compounds are typically strong oxidants or exist only in highly acidic solutions. [1] Red α-PbO and yellow β-PbO The mixed valence oxide Pb 3 O 4 Black PbO 2 which is a strong ...
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 ...
Both the oxidation and reduction steps are pH dependent. Figure 1 shows the standard potentials at pH 0 (strongly acidic) as referenced to the normal hydrogen electrode (NHE). 2 half reactions (at pH = 0) Oxidation 2H 2 O → 4H + + 4e − + O 2 E° = +1.23 V vs. NHE Reduction 4H + + 4e − → 2H 2 E° = 0.00 V vs. NHE