Page 119 - Chemical and process design handbook

Speight_Part II_A 11/7/01 3:16 PM Page 2.60

ANILINE

Aniline is an important derivative of benzene that can be made in two steps
by nitration to nitrobenzene and either catalytic hydrogenation or acidic
metal reduction to aniline.
C H + HNO → C H NO + H O
6 6 3 6 5 2 2
C H NO + 3H → C H NH + 2H O
6 5 2 2 6 5 2 2
Both steps occur in excellent yield.
The reaction of ammonia and phenol is also being used for aniline pro-
duction.
C H OH + NH → C H NH + H O
6 5 3 6 5 2 2
Major uses of aniline include the manufacture of p,p′-methylene
diphenyl diisocyanate (MDI), which is polymerized with a diol (HO-R-
OH) to give a polyurethane. Two moles of aniline react with formaldehyde
to give p,p′-methylenedianiline (MDA), which reacts with phosgene to
give p,p′-methylene diphenyl diisocyanate. Toluene diisocyanate (TDI)
also reacts with a diol to give a polyurethane, but polyurethanes derived
from p,p′-methylene diphenyl diisocyanate are more rigid than those from
toluene diisocyanate.
Aniline is used in the rubber industry for the manufacture of various
vulcanization accelerators and age resistors. Aniline is also used in the pro-
duction of herbicides, dyes and pigments, and specialty fibers.

See Amination.

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