Phthalic anhydride

Phthalic anhydride

Phthalic anhydride is the anhydride of phthalic acid. It has a normal melting point of 130.8°C and a normal boiling of 284.5°C. It dissolves in alcohol and some other organic solvents.

Phthalic anhydride is obtained either by catalytic oxidation of ortho-xylene with O₂ (oxygen) or by catalytic oxidation of naphthalene.

It is hydrolyzed by hot water, forming ortho-phthalic acid.

Phthalic anhydride is widely used in industry in the production of dyes (rhodamine, anthraquinone derivatives), insecticides, plasticizers, in pharmacy, in analytic chemistry, etc.