Chemistry Reference
In-Depth Information
Scheme 14.4
Scheme 14.5
Scheme 14.6
4.2 Examples of homogeneous catalysis
in practice
4-ADPA, an intermediate for the manufacture of
antioxidants in the rubber chemicals industry (Fig.
14.2). This process takes advantage of the ability of
nitroaromatics to undergo nucleophilic substitution,
in this case for hydrogen. Attack of aniline on
nitrobenzene promoted by Me
4
N
+
OH
-
results in
the formation of an intermediate Meisenheimer
complex. The complex loses OH
-
, regenerating the
catalyst and giving a nitroso compound. Catalytic
hydrogenation gives 4-ADPA. This approach elimi-
Homogeneous catalysis is being employed more
widely for industrial production. In many cases,
catalysis will involve the use of transition metal com-
plexes to promote reactions. However, a particularly
elegant example of catalysis not involving a transi-
tion metal intermediate is the route adopted by
Solutia (formerly Monsanto) for the production of
