Maleic anhydride is an important organic chemical raw material used mainly for synthesizing unsaturated polyester resins, coatings, pharmaceutics, pesticides, lubricating oil additives, foodstuff additives etc. At room temperature, it is a white flaky crystal with irritant odour and sour, inflammable and sublimating. It can be freely dissolved in water to form maleic acid. It has a specific density of 1.480, a melting point of 52.85 °C, and a boiling point of 202°C.