(chemistry) of, relating to, or derived from naphthalene or phthalic acid

(organic chemistry) 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.

(organic chemistry) Any of three isomeric aromatic organic benzenedicarboxylic acids, C₆H₄(COOH)₂; especially the ortho- isomer manufactured from naphthalene, used in the synthesis of dyes, perfumes and other compounds.

plural of phthalic acid