Page 76 - Chemical and process design handbook

Speight_Part II_A 11/7/01 3:16 PM Page 2.17

ACETONE 2.17
The overall yield is 90 to 92 percent. By-products are acetophenone,
2-phenylpropan-2-ol, and α-methylstyrene. Acetone is distilled first at
o
boiling point 56 C.
Vacuum distillation recovers the unreacted cumene and yields α−methyl-
styrene, which can be hydrogenated back to cumene and recycled. Further
o
distillation separates phenol, boiling point 181 C, and acetophenone, boil-
o
ing point 202 C.
In older industrial processes, acetone is prepared (1) by passing the
vapors of acetic acid over heated lime. Calcium acetate is produced in the
first step followed by a breakdown of the acetate into acetone and calcium
carbonate:
CH CO H + CaO → (CH CO ) Ca + H O
3 2 3 2 2 2
(CH CO ) Ca → CH COCH + CaCO
3 2 2 3 3 3
and (2) by fermentation of starches, such as maize, which produce acetone
along with butyl alcohol.
Acetone is a very important solvent and is widely used in the manufac-
ture of plastics and lacquers. For storage purposes, acetone may be used as
a solvent for acetylene. Acetone is the starting ingredient or intermediate
for numerous organic syntheses. Closely related, industrially important
compounds are diacetone alcohol [CH COCH COH(CH ) ], which is used
3 2
3
2
as a solvent for cellulose acetate and nitrocellulose, as well as for various
resins and gums, and as a thinner for lacquers and inking materials.
Acetone is used for the production of methyl methacrylate, solvents,
bisphenol A, aldol chemicals, and pharmaceuticals.
Methyl methacrylate is manufactured and then polymerized to
poly(methyl methacrylate), an important plastic known for its clarity and
used as a glass substitute.
Aldol chemicals refer to a variety of substances desired from acetone
involving an aldol condensation in a portion of their synthesis. The most
important of these chemicals is methyl iso-butyl ketone (MIBK), a com-
mon solvent for many plastics, pesticides, adhesives, and pharmaceuticals.
Bisphenol A is manufactured by a reaction between phenol and acetone,
the two products from the cumene hydroperoxide rearrangement.
Bisphenol A is an important diol monomer used in the synthesis of poly-
carbonates and epoxy resins.
A product known as synthetic methyl acetone is prepared by mixing
acetone (50%), methyl acetate (30%), and methyl alcohol (20%) and is
used widely for coagulating latex and in paint removers and lacquers.