What is "phthalic anhydride"

n. (context organic compound English) The acid anhydride of phthalic acid; manufactured by the oxidation of xylene or naphthalene, widely used in the synthesis of dyes, insecticides, plasticizers and pharmaceuticals.

n. a white cyclic anhydride

Phthalic anhydride is the organic compound with the formula CH(CO)O. It is the anhydride of phthalic acid. Phthalic anhydride is a principal commercial form of phthalic acid. It was the first anhydride of a dicarboxylic acid to be used commercially. This colourless solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics. In 2000, the worldwide production volume was estimated to be about 3 million tonnes per year.