Maleic anhydride, also known as maleic anhydride, is a colorless crystalline powder with a strong irritating odor. It was first obtained from malic acid in 1834. Maleic anhydride is produced by catalytic oxidation of benzene or by air oxidation of butene or butane. It is soluble in ethanol, poorly soluble in petroleum ether, and reacts with hot water to form maleic acid. It is used in Diels-Alder reactions, the production of pharmaceuticals, pesticides, dye intermediates, polyester resins, alkyd resins, maleic acid and other organic acids, and also serves as a preservative for fats and oils.