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

Mechanisms of industrial processes
12.3.3 Hydrocyanation of ethene and of butadiene
The 16-electron complex NiL, (L = tris-o-tolylphosphite) catalyses the addition of
hydrogen cyanide to ethene and to 1, 3-butadiene below 25°C. A catalytic cycle
for ethene based on the alternant formation of 16- and 18-electron intermediates
is shown in Fig. 12.3. The inner route is considered tobe the more likely, but the
outer one cannot be excluded. IfDCN is used instead ofHCN, deuterium appears
at both the a and f3 positions in the resulting CH,CH 2 CN. This shows that the
addition of Ni-H (Ni-D) to C 2 H 4 is reversible.
The Du Pont process for the manufacture of adiponitrile (1, 4-dicyanobutane)
from butadiene depends on nickel catalysed hydrocyanation. Adiponitrile is the
precursor to 1, 6-diaminohexane which is used to make Nylon 6, 6. The other
component, adipic acid (1, 6-hexanedioic acid) is usually made by oxidation of
cyclohexane, although in principle it could also be obtained from the dinitrile. The
H0 2 C(CH 2 ) 4 C0 2 H + H 2 N(CHJ.NH 2
- - + + -
---> ... 0 2 C(CH 2 ) 4C0 2 ···H,N(CH 2 ) 6NH, ·· ·0 2C(CH 2 ) 4 C0 2 •••
270'C
--->
-H 2 0
Salt
o o o o
11 11 11 11
- -C(CH 2 ) 4 CNH(CH 2 ) 6 NHC(CH 2 ) 4CNH-- (Nylon 6, 6).
J (18)
1'1
EtCN /' !
NiL2(CN)2(16)
(deoctivotion >25"C)
(18)
HCN
Fig. 12.3 Catalytic cycle for hydrocyanation of ethene.
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