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therefore expensive electrode materials have to
be used for it. As a result the maintenance cost
of the counter anode is often much higher than
that of the working cathode. These problems
make industrialization of organic
electrosynthesis difficult and, as mentioned
earlier, it must be recognized that organic
electrosynthesis has severe limitations. In spite
of this, cathodic hydrocoupling of acrylonitrile
has been used for more than 40 years
worldwide. This is because the product,
adiponitrile, is profitable because of its
versatility and in high demand because of its
excellent physical properties. The cathodic
hydrocoupling method is also superior to other
synthetic procedures from an energy cost
aspect. Initially, the process was operated using
a divided cell, but later electrolysis without a
diaphragm was developed in order to decrease
the electric power cost of the process.
8.2 Examples
8.2.1 Electrosynthesis of Adiponitrile
6,6-Nylon is produced by catalytic
hydrogenation of adiponitrile to form
hexamethylenediamine, followed by
dehydration-condensation with adipic acid, as
shown in
Eq. 8.1
. Since 6,6-nylon has excellent
strength and durability, it is widely used in tyre
cord, synthetic clothes, engineering plastics etc.
Hexamethylenediisocyanate as a starting
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