• Source: Lead(IV) acetate

Lead(IV) acetate or lead tetraacetate is an metalorganic compound with chemical formula Pb(C2H3O2)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.




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.




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:

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, 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, and α-oxygen ether C−H bonds, for example the conversion of dioxane to 2-acetoxy-1,4-dioxane
An alternative reagent to bromine in Hofmann rearrangement
Dehydrogenation of hydrazones and hydrazines, for example that of hexafluoroacetone hydrazone to bis(trifluoromethyl)diazomethane
Cleavage of α-hydroxy acids 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.
Reaction with alkenes to form γ-lactones
Oxidation of alcohols carrying a δ-proton to cyclic ethers.
Oxidative cleavage of certain allyl alcohols in conjunction with ozone:
Transformation of 1,2-dicarboxylic acids or cyclic anhydrides to alkenes

Conversion of acetophenones to phenyl acetic acids
Decarboxylation of carboxylic acids to alkyl halides in the Kochi reaction




Safety


Lead(IV) acetate is toxic. It is a neurotoxin. It affects the gum tissue, central nervous system, kidneys, blood, and reproductive system.




References

Kata Kunci Pencarian:

• Timbal(IV) asetat
• Timbal(II) asetat
• Kamus rumus kimia
• Neodimium
• Talium
• Lead(IV) acetate
• Lead acetate
• Lead(II) acetate
• Tin(IV) acetate
• Kochi reaction
• Hunsdiecker reaction
• Benzotriazole
• Aryne
• Lead(II,IV) oxide
• Lead dioxide