What molecule am I?
Tannins are polyphenolic biomolecules with carbohydrate backbones that are found in in a wide range of plants. Tannic acid is a specific tannin that formally contains 10 galloyl (3,4,5-trihydroxyphenyl) units surrounding a glucose center. Commercial tannic acid, however, consists of molecules with 2–12 galloyl moieties.
Tannic acid contains no carboxyl groups, but is weakly acidic because of the multiplicity of phenolic hydroxyls. The hydroxyls also cause it to be extremely soluble in water. All regulatory authorities classify it as a nonhazardous substance.
As the name implies, tannins are used in leather tanning. Other commercial uses are in dyeing, ink manufacture, paper sizing, food and wine processing, and production of gallic acid and pyrogallol.
Early reviews of tannins and tannic acid include The Natural Organic Tannins (M. Nierenstein, 1934) and “Gallotannine und Ellagen-gerbstoffe” (O. Th. Schmidt, 1956).
Tannic acid hazard information
| GHS* classification: not a hazardous substance |
MOTW update
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Tannic acid fast facts
| CAS Reg. No. | 1401-55-4 |
| Molar mass | 1701.2 g/mol |
| Empirical formula | C76H52O46 |
| Appearance | Light yellow to tan solid |
| Boiling point | 218 ºC (dec.) |
| Water solubility | 2850 g/L* |
*Some sources report 250 g/L.
Learn more about this molecule from CAS, the most authoritative and comprehensive source for chemical information.
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