Phthalic anhydride, an organic compound with the chemical formula C8H4O3, is a cyclic anhydride formed by dehydration within the phthalic acid molecule. It is a white crystalline powder, insoluble in cold water, slightly soluble in hot water, ether, soluble in ethanol, pyridine, benzene, carbon disulfide, etc. It is an important organic chemical material and an important intermediate in the preparation of phthalate plasticizers, paints, saccharin, dyes and organic compounds.