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