The phthaleïn formed from gallic acid and phthalic anhydride really results from the union of the latter with pyrogallol.
phthalic acid, which was discovered in 1836 by Laurent, is a product of the oxidation of many benzenoid compounds.
Dilute nitric acid oxidizes it to phthalic acid, and sodium reduces it in alcoholic solution to hydrindene, C9H10.
It condenses with phthalic anhydride to form rhodamine, and with succinic anhydride to rhodamine S.
phthalic phthal·ic (thāl'ĭk, fthāl'-)
Relating to or derived from naphthalene.
Relating to phthalic acid.