Tannic

Tannic acid is a specific form of tannin, a type of polyphenol. Its weak acidity (pKa around 10) is due to the numerous phenol groups in the structure. The chemical formula for commercial tannic acid is often given as C76H52O46, which corresponds with decagalloyl glucose, but in fact it is a mixture of polygalloyl glucoses or polygalloyl quinic acid esters with the number of galloyl moieties per molecule ranging from 2 up to 12 depending on the plant source used to extract the tannic acid. Commercial tannic acid is usually extracted from any of the following plant parts: Tara pods (Caesalpinia spinosa), galls from a variety of species of trees, or from the bark of Quercus robur or Sicilian sumac (Rhus coriaria).

Chemical structure

Tannic acid is a polymer of gallic acid molecules and glucose. The gallic acid molecules are linked together in a complex structure by ester bonds. The glucose molecule is at the center of the structure, and the gallic acid molecules are attached to it.

Uses

Tannic acid has been used in the traditional medicine for the treatment of various diseases. It has astringent properties, which makes it useful for treating diarrhea and sore throat. It is also used in the leather industry for tanning hides, and in the wine industry to adjust the tannin content of wine.

Safety

Tannic acid is generally considered safe for topical use. However, it can cause side effects such as stomach irritation, nausea, and vomiting if ingested in large amounts. It can also cause skin irritation in some people.

See also

• Tannin
• Polyphenol
• Gallic acid

Tannic Resources
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