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orthophthalic acid

[awr-thuh-thal-ik, -thuh f-thal-] /ˌɔr θəˈθæl ɪk, -θəfˈθæl-/
noun, Chemistry
See under phthalic acid (def 1).

phthalic acid

Chemistry. any of three isomeric acids having the formula C 8 H 6 O 4 , especially the ortho isomer (orthophthalic acid) a colorless, crystalline, slightly water-soluble solid used chiefly in the manufacture of dyes, medicine, and perfume.
1855-60 Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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British Dictionary definitions for ortho phthalic acid

phthalic acid

/ˈθælɪk; ˈfθæl-/
a soluble colourless crystalline acid used in the synthesis of dyes and perfumes; 1,2-benzenedicarboxylic acid. Formula: C6H4(COOH)2
Word Origin
C19 phthalic, from phthal- (see phthalein) +-ic
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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ortho phthalic acid in Medicine

phthalic acid n.
A colorless crystalline organic acid prepared from naphthalene and used in the synthesis of dyes and other organic compounds.

The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.
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ortho phthalic acid in Science
phthalic acid
  (thāl'ĭk, fthāl'-)   
A colorless, crystalline organic acid prepared from naphthalene and used in the synthesis of dyes, perfumes, and other organic compounds. Chemical formula: C8H6O4.
The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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Encyclopedia Article for ortho phthalic acid

phthalic acid

colourless, crystalline organic compound ordinarily produced and sold in the form of its anhydride. The annual production of phthalic anhydride exceeded 1,000,000 metric tons in the late 20th century; most of it was used as an ingredient of polyesters, including alkyd resins (vehicles for paints and enamels), and simple esters used as plasticizers for polyvinyl chloride and other polymers. Smaller quantities were consumed in the manufacture of anthraquinone (a dye intermediate), phenolphthalein (a laxative and acid-base indicator), and phthalocyanine pigments

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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