Page 26 - Chemical and process design handbook

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CONDENSATION

AND ADDITION

There are only a few products manufactured in any considerable tonnage
by condensation and addition (Friedel-Crafts) reactions, but those that are
find use in several different intermediates and particularly in making high-
quality vat dyes.
The agent employed in this reaction is usually an acid chloride or anhy-
dride, catalyzed with aluminum chloride. Phthalic anhydride reacts with
chlorobenzene to give p-chlorobenzoylbenzoic acid and, in a continuing
action, the p-chlorobenzoylbenzoic acid forms β-chloroanthraquinone.
Since anthraquinone is a relatively rare and expensive component of
coal tar and petroleum, this type of reaction has been the basis for making
relatively inexpensive anthraquinone derivatives for use in making many
fast dyes for cotton.
Friedel-Crafts reactions are highly corrosive, and the aluminum-con-
taining residues are difficult to dispose.

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