Maleic anhydride, also known as cis-butenedioic anhydride, is a colorless orthorhombic needle-like crystal or white crystalline powder. It is soluble in water, benzene, chloroform, and most organic solvents. At 25°C, its solubility in the following solvents (g/100g) is: ethyl acetate 112, chloroform 52.5, benzene 50, petroleum ether 0.25. It dissolves in alcohol to form esters and is soluble in dioxane. It sublimes upon heating. When exposed to high temperatures, open flames, or contact with oxidizing agents, there is a risk of combustion. It is corrosive. It slowly hydrolyzes in cold water to form maleic acid. Contact with strong oxidizing agents can cause combustion. If the temperature exceeds 66°C, polymerization may occur upon contact with amines or alkali metals.

Uses: Maleic anhydride is used as a reagent for determining organic compounds with conjugated double bonds. It is also used in synthetic resins, coatings, pesticides, pharmaceuticals, food, and lubricant additives, among others.