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gallic acid

gallic acid or 3,4,5-trihydroxybenzoic acid (trī´hīdrŏk´sēbĕnzō´Ĭk), C6H2(OH)3CO2H, colorless crystalline organic acid found in gallnuts, sumach, tea leaves, oak bark, and many other plants, both in its free state and as part of the tannin molecule (see tannin). Since gallic acid has hydroxyl groups and a carboxylic acid group in the same molecule, two molecules of it can react with one another to form an ester, digallic acid. Gallic acid is obtained by the hydrolysis of tannic acid with sulfuric acid. When heated above 220°C, gallic acid loses carbon dioxide to form pyrogallol, or 1,2,3-trihydroxybenzene, C6H3(OH)3, which is used in the production of azo dyes and photographic developers and in laboratories for absorbing oxygen.

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"gallic acid." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

"gallic acid." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (June 26, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/gallic-acid

"gallic acid." The Columbia Encyclopedia, 6th ed.. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/gallic-acid

gallic acid

gal·lic ac·id / ˈgalik; ˈgôlik/ • n. Chem. an acid, C6H2(OH)3COOH, extracted from oak galls and other vegetable products, formerly used in making ink.

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"gallic acid." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

"gallic acid." The Oxford Pocket Dictionary of Current English. . Encyclopedia.com. (June 26, 2017). http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/gallic-acid

"gallic acid." The Oxford Pocket Dictionary of Current English. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/humanities/dictionaries-thesauruses-pictures-and-press-releases/gallic-acid

benzoic acid, 3,4,5-trihydroxy-

3,4,5-trihydroxy- benzoic acid, IUPAC name for gallic acid.

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"benzoic acid, 3,4,5-trihydroxy-." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. 26 Jun. 2017 <http://www.encyclopedia.com>.

"benzoic acid, 3,4,5-trihydroxy-." The Columbia Encyclopedia, 6th ed.. . Encyclopedia.com. (June 26, 2017). http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/benzoic-acid-345-trihydroxy

"benzoic acid, 3,4,5-trihydroxy-." The Columbia Encyclopedia, 6th ed.. . Retrieved June 26, 2017 from Encyclopedia.com: http://www.encyclopedia.com/reference/encyclopedias-almanacs-transcripts-and-maps/benzoic-acid-345-trihydroxy