Adjective
Pertaining to, or designating, a dibasic acid obtained by the oxidation of naphthalene and allied substances.
Source: Webster's dictionaryA process for the creation of saccharin from phthalic anhydride was developed in 1950, and, currently, saccharin is created by this process as well as the original process by which it was discovered. Source: Internet
The most common plasticizers are derivatives of phthalic acid. Source: Internet