Introduction
<P>Palladium(II) acetate [Pd(OAc)
2] [CAS: 3375-31-3] is a commercially available reagent, which is stable and soluble
in organic solvents. It has a melting point of 195 °C (dec.). It can be prepared from
metallic palladium by dissolving in acetic acid containing nitric acid. It may contain
nitrate anion as impurity. Pd(OAc)
2 is purified by dissolving it in hot benzene and concentrating the benzene solution
after removing the insoluble part. Pure Pd(OAc)
2 can be obtained as needle-like crystals by recrystallization.
</P><P>Palladium(II) acetate is used for oxidative addition, insertion, transmetalation
and reductive elimination reactions. It is used for allylic oxidation (acetoxylation),
e.g. oxidation of cyclohexene to 2-acetoxycyclohexene. Unsaturated aldehydes can be
elongated by one carbon atom. Silyl enols undergo transmetalation followed by intramolecular
alkene insertion and β-elimination. Acetoxybenzene is prepared by reaction of benzene
with Pd(OAc)
2. This is a useful method for phenol production from benzene. Pd(OAc)
2 is widely used in the presence of phosphine ligand and as a base in Heck reaction,
for coupling aryl or vinyl halides with alkenes.
[
1]
In the presence of TBAB, it catalyses direct homocoupling of aryl halides.
[
2]
It is also used to improve Wacker oxidation of terminal alkenes to 2-alkanones with
p-benzoquinone, which improves the reaction rate 50-fold.
[
3]
It is efficient in ligandless Suzuki cross-coupling of aryl boronic acids with aryl
iodides.
[
4]
A stoichiometric quantity is required in Buchwald-Hartwig reaction of C-N bond formation.
Selective reduction of alkynes is catalyzed by Pd(OAc)
2 with NaOMe
[
5]
and reduction of aryl/enol triflates by this catalyst is reported.
[
6]
Pd(OAc)
2 was microencapsulated in polyurea for making it reusable and recoverable catalyst
for hydrogenation.
[
7]
</P>
