_P.-Powell-auth.-Principles-of-Organometallic-Chemistry-Springer-Netherlands-1988

Catalysis of reactions of alkenes by transition metal complexes
~ L/2~
y
THF
Pd
~ 09
~ ~ -------- RO-Pd
RO -P ROH---Pd (n.m.r.) / \
1 !""0 l: 11
L L 1
~ ~RO"
OR
H
ROH
(X-roy, n.m.r)
~OR
1, 3, 7- octotriene
1- methoxy -3, 7-octotriene
Fig. 12.8 Linear telomerization of 1. 3-butadiene, catalysed by palladium complexes.
compounds HX such as ROH, R 2 NH, RC0 2 H or CH 2 (COOEt) 2 , the major products
are linear telomers. It does not appear that these reactions have been used
industrially, although they have been included in some syntheses of natural
products. The cycle shown in Fig. 12.8 accounts for the catalytic production of 1-
methoxy-3, 7 -octadiene from methanol and butadiene. Some of the intermediates
have been characterized by n.m.r. (IH. 13 C, 31 P) and where indicated, by X-ray
diffraction.
12.3.6 Ziegler-Natta catalysis
While aluminium alkyls on their own convert ethene into oligomers (p. 80), in
the presence oftraces ofnickel termination occurs after only one step, so that the
dimer, butene, is produced. This observation led Ziegler to study the effect of
compounds of other transition metals as cocatalysts. With titanium or zirconium
. compounds in particular, rapid polymerization of ethene occurs at 50°C/l o atm
leading to a crystalline, high density polyethene (HDPE) which consists of long
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