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Palladium(II) acetate

 
Palladium(II) Acetate

 
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Palladium(II) acetate
 
 
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Palladium(II) acetate is a chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 of palladium
Palladium

Palladium is a rare and lustrous silvery-white metal that was discovered in 1803 by William Hyde Wollaston, who named it palladium after the 2 Pallas, which in turn, was named after the epithet of the Greek mythology goddess Athena, acquired by her when she slew Athena#Pallas_Athena....
 described by the formula Pd(O2CCH3)2 or Pd(OAc)2. It is considered more reactive than the related platinum. It is soluble in many organic solvents.

adium(II) acetate is trimeric, consisting of an equilateral triangle of Pd atoms each pair of which is bridged with two acetate groups in a butterfly conformation.






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Palladium(II) acetate is a chemical compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 of palladium
Palladium

Palladium is a rare and lustrous silvery-white metal that was discovered in 1803 by William Hyde Wollaston, who named it palladium after the 2 Pallas, which in turn, was named after the epithet of the Greek mythology goddess Athena, acquired by her when she slew Athena#Pallas_Athena....
 described by the formula Pd(O2CCH3)2 or Pd(OAc)2. It is considered more reactive than the related platinum. It is soluble in many organic solvents.

Structure

Palladium(II) acetate is trimeric, consisting of an equilateral triangle of Pd atoms each pair of which is bridged with two acetate groups in a butterfly conformation. Each metal atom achieves approximate square planar co-ordination.

Preparation

Palladium acetate can be prepared by refluxing palladium sponge with hot glacial acetic acid
Acetic acid

Acetic acid, CH3COOH, also known as ethanoic acid, is an organic acid which gives vinegar its sour taste and pungent smell. Pure, water-free acetic acid is a colourless liquid that absorbs water from the environment , and freezes at 16.7 Celsius to a colourless crystalline solid....
 and nitric acid
Nitric acid

Nitric acid , also known as aqua fortis and spirit of nitre, is a highly corrosion and toxic strong acid that can cause severe burns....
. An excess of palladium sponge is used to prevent contamination by PdNO3·OAc.
Pd + 2 HNO3 ? Pd(NO3)2 + H2
Pd(NO3)2 + 2 CH3COOH ? Pd(O2CCH3)2 + 2 HNO3


Palladium(II) propionate is prepared analogously; other carboxylates are prepared by reacting palladium(II) acetate with the appropriate carboxylic acid.

Reactions

When warmed with alcohols, or on prolonged boiling with other solvents, palladium(II) acetate decomposes to palladium.

Uses


Catalysis

Palladium acetate is a catalyst for many organic reactions by combining with many common classes of organic compounds such as alkenes, dienes, and alkyl, aryl, and vinyl halides to form reactive adducts. Alkenes and p-allyl
Allyl

An allyl group is an alkene hydrocarbon group with the formula H2C=CH-CH2-. It is made up of a vinyl group, CH2=CH-, attached to a methylene -CH2....
 coordination to palladium(II) acetate involves sigma-type donation from the pi orbital of the alkene or p-allyl with concomitant pi-backbonding into an empty pi* orbital on the alkene or p-allyl. The greater the sigma donation to the metal is, the greater the pi-backbonding. The greater the pi-backbonding is, the greater the reduction in the bond order of the alkene or p-allyl. Reduction of the alkenes or p-allyl by coordination to palladium(II) acetate reverses the reactivity of the organic ligand allowing them to undergo reactions with nucleophiles rather than electrophiles.

Examples of palladium(II) acetate catalyzed reactions are:
  • Vinylation: An example is the Heck reaction
    Heck reaction

    The Heck reaction is the chemical reaction of an unsaturated halide with an alkene and a strong base and palladium catalyst to form a substituted alkene....
  • Rearrangement of Acyclic Dienes: An example is the Cope reaction
    Cope reaction

    The Cope reaction or Cope elimination, developed by Arthur C. Cope, is an elimination reaction of an amine oxide to form an alkene and a hydroxyl amine....
  • Carbonylation reaction: carboxylation of aryl halides and benzyl chloride derivatives in ionic liquid media (l-butyl-3-methylimidazolium hexafluorophosphate, tetrafluoroborate, and Aliquat336 )
  • Reductive amination
    Reductive amination

    Reductive amination is a chemical reaction which involves the conversion of a carbonyl group to an amine, via an intermediate imine. The carbonyl group is most commonly a ketone or an aldehyde....
     of aldehydes or ketones using potassium formate.
  • Wacker process
    Wacker process

    The Wacker process or the Hoechst-Wacker process originally referred to the oxidation of ethylene to acetaldehyde by oxygen in water in the presence of a tetrachloropalladate catalysis....
    : the oxidation of ethylene in water to form acetaldehyde (precursor to poly(vinyl acetate), a common glue).
  • Buchwald-Hartwig synthesis of aryl amines from aryl halides/pseudohalides and primary or secondary amines.


Pd(O2CCH3)2 converts aryl bromides into aryltrimethylsilanes, an important functional group in many organic compounds including the fungicide "Latitude".
RC6H4Br + Si2(CH3)6 ? RC6H4Si(CH3)3 + Si(CH3)3Br
Pd(O2CCH3)2 is compatible with the electronic properties of aryl bromides, and unlike other methods of synthesis, this method does not require high pressure equipment.

Precursor to other Pd compounds

Palladium acetate is used to produce other palladium(II) compounds. For example, phenylpalladium acetate, used to isomerize allylic alcohols to aldehydes, is prepared by the following reaction:

Hg(C6H5)(CH3COO) + Pd(CH3COO)2 ? Pd(C6H5)(O2CCH3) + Hg(O2CCH3)2


Palladium(II) acetate reacts with acetylacetone
Acetylacetone

Acetylacetone is an organic compound with molecular formula C5H8O2. This diketone is formally named 2,4-pentanedione....
 to produce Pd(acac)2, a precursor to Pd(0).

Light or heat reduce palladium acetate to give thin layers of palladium and can produce nanowires and colloids.