Chemistry Reference
In-Depth Information
Fe - C
= 2.09 (2) Å
α
Cp
Fe - C
= 2.32 (2) Å
Fe
β
Fe
C
β
C
CO
C
α
C
1.34 (2)
1.42 (2)
OMe
C
O
C
O
C
Figure 6.1
An iron-alkene complex. Reprinted with permission from Chang, T. C. T. et al. J. Am. Chem. Soc.,
1981, 103 (24), pp 7361-7362
c
1981 American Chemical Society.
Nuc
Nuc
M
M
+
Scheme 6.1
Nuc
Nuc
M
M
+
Scheme 6.2
Nuc
Nuc
•
•
M
M
+
M
Nuc
Scheme 6.3
operates appears to depend on the concentration of the different ligands available to palladium: the latter is
likely to operate under the conditions employed in the industrial process.
-Hydride elimination then gives an
2
-enol complex
6.4
. Reinsertion generates an isomeric
1
-complex
6.5
, which undergoes a second
-hydride
elimination to give acetaldehyde. The reductive elimination of HCl has, at this point, reduced the palladium
to zero, so the process is not catalytic. Copper salts are included: copper(II) oxidizes Pd(0) to Pd(II), but is
reduced to copper(I). The reaction is run in the presence of air. Oxygen from air re-oxidizes the copper(I) to
copper(II) in the second catalytic cycle.
The chemistry of the Wacker reaction is not limited to ethylene, but may be extended to a wide range of
alkenes, and is useful throughout organic synthesis.
4
For the synthesis of complex molecules, the Wacker
