Phthalic Anhydride

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phthalic anhydride

[′thal·ik an′hī‚drīd]
(organic chemistry)
C6H4(CO)2O White crystals, melting at 131°C; sublimes when heated; slightly soluble in ether and hot water, soluble in alcohol; used to make dyes, resins, plasticizers, and insect repellents.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Phthalic Anhydride


(also acid phthalic anhydride), a colorless crystalline compound, with a melting point of 130.8°C and a boiling point of 284.5°C. It is practically insoluble in water and moderately soluble in organic solvents.

Phthalic anhydride is an important starting product in the manufacture of various phthalic-acid derivatives, including esters, phthalimide, and phthalonitrile. The condensation of phthalic anhydride with phenols is used to obtain dyes, such as phenolphthalein. Much of the phthalic anhydride produced is used in the manufacture of glyptal, penta resins, intermediate products, dyes—derivatives of fluorescein, rhodamine, and anthra-quinone—and drugs, such as the anticoagulants Ftalazol (phthalylsulfathiazole) and Fenilin (phenindione).

Phthalic anhydride is prepared by the catalytic oxidation of naphthalene or ortho-xylene by air in the gaseous phase.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.