Chemistry Reference
In-Depth Information
BENZENE DERIVATIVES
M
ALEIC
A
NHYDRIDE
Uses
The largest single use of maleic anhydride is in the
preparation of unsaturated polyester resins. It is first
esterified with a polyalcohol (two or more hydroxyls) and
then the double bond is copolymerized (crosslinked) with
a vinyl monomer such as styrene to form a rigid structure.
Such resins are usually reinforced with fiberglass (FRP).
Maleic anhydride is also used to make oil additives and
agricultural chemicals.
Manufacture
O
+
O
2
(from air)
catalyst
O
catalyst
+
CH
3
CH
2
CH
2
CH
3
O
2
(from air)
O
butane
Suppliers
Bayer, Huntsman, Ashland, BP Amoco.
For many years the
catalytic air oxidation
of benzene was the main source
of maleic anhydride. Obviously, two carbons from each ring are wasted as
carbon dioxide in this process. Although some is still made that way, most
modern maleic anhydride plants are based on
butane oxidation
. Because
butane is forecast to be plentiful and low-cost, new routes to four-carbon
chemicals from maleic anhydride are under active development.
Unsaturated polyester resins
based on maleic anhydride are widely used
in coatings to manufacture boat hulls and truck caps and a variety of other
uses where a smooth, weatherproof, hard-surfaced material is desired.
Because these resin types are inherently brittle, fiberglass is frequently added
for reinforcement. Consumption of unsaturated polyesters in the U.S. is well
over a billion pounds per year, with about 50% going into construction and
the marine industry.
