Maleic anhydride is an organic compound with the formula C2H2(CO)2O. It is the acid anhydride of maleic acid and in its pure state it is a colourless or white solid with an acrid odour.
Maleic anhydride was traditionally manufactured by the oxidation of benzene or other aromatic compounds. As of 2006, only a few smaller plants continue to use benzene; due to rising benzene prices, most maleic anhydride plants now use n-butane.
The unique nature of maleic anhydride's chemical structure results in a highly reactive and versatile raw material. Its unsaturated double bond and acid anhydride group lend themselves to a variety of chemical reactions. Maleic anhydride's largest use today is in the production of unsaturated polyester resins. These resins are used primarily in fibre-reinforced plastics; materials with a wide and growing range of applications in boating, automobile and construction industries.
Another significant use of maleic anhydride is in the manufacture of alkyd resins, which are in turn used in paints and coatings. Other applications where maleic anhydride is used include the production of agricultural chemicals, malic acid, copolymers, fumaric acid, lubricant additives, surfactants and plasticizers.
Future applications are anticipated to be numerous given the versatility and usefulness of this product.