Page 90 - Chemical and process design handbook

Speight_Part II_A 11/7/01 3:16 PM Page 2.31

ACETIC ACID 2.31

Reactor Bleacher NOX absorber Crystallizer

Off-gas Water

Air Air
Cyclohexanol-
cyclohexanone Water
mixture

Dibasic acids Adipic acid

Nitric acid
FIGURE 2 Adipic acid manufacture by nitric acid oxidation of cyclohexane

Although the phenol route for making adipic acid is not economically
advantageous because phenol is more expensive than benzene, the phenol
conversion to greater cyclohexanone percentages can be used successfully
for caprolactam manufacture, where cyclohexanone is necessary.
Adipic acid is used to make nylon 6,6 fibers and nylon 6,6 resins; it is
also used in the manufacture of polyurethanes and plasticizers.
Other starting materials for adipic acid include butadiene and 1,4-disubsti-
tuted-2-butene, which involves dicarbonylation with palladium chloride.
Polar, aprotic, and nonbasic solvents are preferred for this reaction to avoid
unwanted side products from hydrogenolysis or isomerization.

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