Page 243 - Chemical and process design handbook

Speight_Part II_C 11/7/01 3:08 PM Page 2.183

CUMENE

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Cumene (iso-propyl benzene, boiling point: 152.4 C, density: 0.8619,
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flash point: 44 C) is an important intermediate in the manufacture of
phenol and acetone.
Cumene is manufactured by reacting benzene with propylene over a cat-
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alyst such as a phosphoric acid derivative at 175 to 250 C and 400 to 600
psi (Fig. 1). A refinery cut of mixed propylene-propane is frequently used
instead of the more expensive pure propylene. Benzene is provided in sub-
stantial excess to avoid polyalkylation. The yield is near quantitative (in
excess of 90 percent) based on propylene.

C H + CH CH=CH → C H CH(CH )
6 6 3 2 6 5 3 2
Excess benzene stops the reaction at the monoalkylated stage and
prevents the polymerization of propylene. The cumene is separated by
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distillation, boiling point 153 C. Other catalysts that have been used are
aluminum chloride and sulfuric acid.
Cumene is used to manufacture phenol, acetone, and α-methylstyrene

See Benzene.

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