Chemistry Reference
In-Depth Information
Scheme 14.9
Scheme 14.10
approach has been the development of a process
for the hydroformylation of propene to give
n
-
butyraldehyde (Scheme 14.10).
Hydroformylation, another mechanistically well-
understood reaction, occurs via complex
1
as the
active catalyst to give a 96 : 4 ratio of
n
-butyralde-
hyde/isobutyraldehyde. The TPPTS ligand is formed
by direct sulfonation of triphenylphosphine [42] and
gives the catalyst high (1.1 kg l
-1
) solubility in water.
Of particular note is that the commercial develop-
ment of this route was extremely rapid. Scale-up
proceeded in only two steps, from a 5-l laboratory
reactor to a 50-l pilot plant, and then to a 120-m
3
commercial production facility (overall, a scaling of
1 : 24 000 in only two steps) [43]. Biphasic catalysis
is now the primary method used for the production
of butyraldehyde (over 6 ¥ 10
5
t year
-1
). This method
also has been investigated for the production of
valeraldehyde, a material produced at a scale of 1.4
¥ 10
4
t year
-1
[44].
Biphasic catalysis also is being used for the pro-
duction of 1-octanol as a plasticiser at a scale of 4.5
¥ 10
3
t year
-1
. In a variation on the well-known buta-
diene telomerisation reaction, butadiene undergoes
dimerisation followed by the addition of a molecule
of water in the presence of a Pd catalyst and the Li
salt of the TPPTS ligand. The resulting unsaturated
alcohol then is reduced catalytically to give 1-octanol
(Scheme 14.11).
Fine chemical synthesis also has benefited from
the use of biphasic catalysis. Vitamin E (worldwide
production of 1 ¥ 10
4
t) [45] is produced via
Rh(TPPTS)-catalysed alkylation of myrcene with
ethyl acetoacetate (Scheme 14.12).
The success of these reactions under biphasic con-
ditions is due to sufficient solubility of the reaction
