Phthalic anhydride is the cyclic dicarboxylic anhydride that is the anhydride of phthalic acid.it is colorless to white lustrous solid in the form of needles with a mild distinctive odor.
Phthalic anhydride is the organic compound with the formula C6H4(CO)2O. It is the anhydride of phthalic acid. Phthalic anhydride is a principal commercial form of phthalic acid.This white solid is an important industrial chemical, especially for the large-scale production of plasticizers for plastics.