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Lead(IV) acetate
Organometallic compound (Pb(C2H3O2)4) From Wikipedia, the free encyclopedia
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Lead(IV) acetate or lead tetraacetate is an metalorganic compound with chemical formula (CH3CO2)4Pb, often abbreviated as Pb(OAc)4, where Ac is acetyl. 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]
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Structure
In the solid state the lead(IV) centers are coordinated by four acetate ions, which are bidentate, each coordinating via two oxygen atoms. The lead atom is 8 coordinate and the O atoms form a flattened trigonal dodecahedron.[3]
Preparation
It is typically prepared by treating of red lead with acetic acid and acetic anhydride (Ac2O), which absorbs water. The net reaction is shown:[4][5]
- Pb3O4 + 4 Ac2O → Pb(OAc)4 + 2 Pb(OAc)2
The remaining lead(II) acetate can be partially oxidized to the tetraacetate by Cl2, with a PbCl2 by-product:
- 2 Pb(OAc)2 + Cl2 → Pb(OAc)4 + PbCl2
Reagent in organic chemistry
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]
- An alternative reagent to bromine in Hofmann rearrangement[9]
- Dehydrogenation of hydrazones and hydrazines, for example that of hexafluoroacetone hydrazone to bis(trifluoromethyl)diazomethane[10][11]
- Cleavage of α-hydroxy acids[12] or 1,2-diols to their corresponding aldehydes or ketones, often replacing ozonolysis; for instance, the oxidation of di-n-butyl D-tartrate to n-butyl glyoxylate.[13]
- Reaction with alkenes to form γ-lactones
- Oxidation of alcohols carrying a δ-proton to cyclic ethers.[14]
- Oxidative cleavage of certain allyl alcohols in conjunction with ozone:[15][16]
- Transformation of 1,2-dicarboxylic acids or cyclic anhydrides to alkenes

- Conversion of acetophenones to phenyl acetic acids[17]
- Decarboxylation of carboxylic acids to alkyl halides in the Kochi reaction[18]
Safety
Lead(IV) acetate is toxic, because of lead. It is a neurotoxin. It badly affects the gum tissue, central nervous system, kidneys, blood, and reproductive system.
References
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