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Chapter 2
2.1.1 Intermediates
[6, Ullmann, 2001, 16, Winnacker and Kuechler, 1982, 19, Booth, 1988]
The number of intermediates actually or potentially available is very large and the technology of
their manufacture is an important part of industrial organic chemistry.
Starting raw materials are aromatic hydrocarbons, such as benzene, toluene, naphthalene,
anthracene, pyrene, phenol, pyridine and carbazol, as well as a wide range of aliphatic
compounds like, e.g. alcohols, carbonic acids, heterocyclic compounds.
Aromatic hydrocarbons undergo four electrophilic substitution reactions – the Friedel-Crafts
reaction, halogenation, nitration and sulphonation – as well as oxidation and reduction. The
reactions lead to substituted hydrocarbons (primary intermediates).
Most manufacturing processes for primary intermediates are run continuously and with
dedicated equipment, because of the large production volume. Subsequent modification steps
are usually carried out in batches. Table 2.2 gives some examples. “One pot” synthesis indicates
that several reaction steps are carried out without work-up of the intermediates.
Compound Unit process
Mode of
operation
Use
Primary Nitrobenzene Nitration Continuous
intermediate Chlorobenzene Chlorination Continuous
p-toluene sulphonic acid Sulphonation Continuous
o-nitroaniline Exchange Continuous
Intermediates 4-chloro-3-nitrobenzene
sulphonic acid
Sulphonation Batch Dyes
2,3,4-trichloro-6nitrophenol
Exchange
Sulphonation
Batch, semi-batch Pesticides
Bromamine acid
Amination
Sulphonation
Bromination
Batch, “one pot” Dyes
Pyrazolone
Diazotisation
Condensation
Batch, “one pot”
Pharmaceuticals
Dyes
Table 2.2: Examples for primary intermediates and intermediates
20 Dezember 2005 OFC_BREF