phthalic

Thus the dinitronaphthol described as Manchester yellow, if heated for some time with dilute nitric acid, furnishes phthalic acid.

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.

Three isomeric phthalic acids are known, but only one of these is of use in the present branch of manufacture.

It condenses with phthalic anhydride to form rhodamine, and with succinic anhydride to rhodamine S.