PRODUCTS

TANNIC ACID

Tannic acid is a specific form of tannin, a type of polyphenol.
Tannic acid's weak acidity (pKa around 6) 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.

CAS: 72401-53-7

IUPAC Name: [2,3-dihydroxy-5-[[(2R,3R,4S,5R)-3,4,5,6-tetrakis[[3,4-dihydroxy-5-(3,4,5-trihydroxybenzoyl)oxybenzoyl]oxy]oxan-2-yl]methoxycarbonyl]phenyl] 3,4,5-trihydroxybenzoate

Molecular Formula: C76H52O46
Molecular Weight: 1701.2 g/mol

Tannic acid is a gallotannin obtained by acylation of the five hydroxy groups of D-glucose by 3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoic acid (a gallic acid dimer).
Tannic acid has a role as a carcinogenic agent, a metabolite and a geroprotector.
Tannic acid is a gallotannin, a D-glucoside and a monosaccharide derivative.
Tannic acid is functionally related to a gallic acid.

According to the definitions provided in external references such as international pharmacopoeia, Food Chemicals Codex and FAO-WHO tannic acid monograph only tannins obtained from the above-mentioned plants can be considered as tannic acid.
Sometimes extracts from chestnut or oak wood are also described as tannic acid but this is an incorrect use of the term.
Tannic acid is a yellow to light brown amorphous powder.

While tannic acid is a specific type of tannin (plant polyphenol), the two terms are sometimes (incorrectly) used interchangeably.
The long-standing misuse of the terms, and its inclusion in scholarly articles has compounded the confusion.
This is particularly widespread in relation to green tea and black tea, both of which contain many different types of tannins not just exclusively tannic acid.

Tannic acid is not an appropriate standard for any type of tannin analysis because of its poorly defined composition.

Pharmaceutical grade tannic acid is generally considered to be pentadigalloylglucose.
Tannic acid has an astringent effect. When used internally, it dehydrates tissues when cause reduction in secretions.
Externally, Tannic acid works through formation of protective layer of harder and constricted cells.
Tannic acid is thought to exert antiviral and antibacterial effects.

Tannic acid is a polyphenolic compound.
Tannic acid is a type of the commercially available tannins.
Tannic acid acts as a weak acid.
Tannic acid is found in the nutgalls formed by insects on twigs of certain oak trees (Quercus infectoria and other Quercus species).
Tannic acid is removed and used as medicine.
In the old days Tannic acid was used as antidote against different poisons.
Nowadays, tannic acid is applied topically for the treatment of cold sores, diaper rash, fever blisters and poison ivy.
Tannic acid is also taken by mouth and applied directly for bleeding, chronic diarrhea, dysentery, bloody urine, painful joints, persistent coughs, and cancer.

Tannic acid is indicated for cold sores, fever blisters, diaper rash, minor burn or sunburn and prickly heat.
Vaginally, tannic acid is used as a douche for leukorrhea.
Tannic acid has been also indicated for sore throat, inflamed tonsils, spongy or receding gums, and acute dermatitis.

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.

The chemistry of tannic acid is complicated because it is of natural origin and consists of a mixture of complex substances.
Although many plant species contain tannins, commercial tannic acid has its origin in Turkish nutgalls gathered from the young twigs of Quercus infectoria.
The powdered galls are extracted with ether, alcohol, and water. Tannic acid is soluble in water.
A yield of 50 to 70 per cent tannic acid is obtained from the water extract.

Tannic acid may be obtained as an amorphous fluffy or dense powder, yellowish-white to light-brown in color.
Tannic acid is further characterized by having an acid reaction in water, essentially no odor, and a strongly astringent taste.
The powder holds about 10 per cent water.
The commercial tannic acid contains many ester linkages and is hydrolysable in the presence of acids, alkalies, or enzymes.
Hydrolysis yields primarily glucose and gallic acid.
Small amounts of other polyhydric alcohols and other phenolic acids such as m-digallic, ellagic and chebulic acids which are chemically related to gallic acid are also found.
Gallic acid is always found in commercial tannic acid in small amounts.

When purified tannic acid is chromatographed, gallotannin consisting of an isomeric mixture of polygalloylated glucose appears as one spot.
Hydrolysis of purified gallotannin yields glucose and gallic acid.
An average structural approximation for gallotannin can be given as eight or nine gallic acid molecules for each glucose molecule.
The gallic acid is bound to glucose as well as to other gallic acid molecules through ester linkages.

The polyphenolic groups in the tannic acid are responsible for its astringent action.
This astringent action is caused by its ability to precipitate protein.
The ability to precipitate protein is partly due to the high molecular weight of gallotannin.

As tannic acid is a polyphenolic compound, its structure has numerous phenol groups.
A particular tannin holds 10 galloyl (3,4,5-trihydroxyphenyl) units adjoining a glucose centre.
However, the mercantile tannic acid structure consists of 2–12 half galloyl molecules.
Tannic acid comprises no carboxyl groups. But, due to the diversity of phenolic hydroxyls, it is weakly acidic.

Uses

Tannins are a basic ingredient in the chemical staining of wood, and are already present in woods like oak, walnut, and mahogany.
Tannic acid can be applied to woods low in tannin so chemical stains that require tannin content will react.
The presence of tannins in the bark of redwood (Sequoia) is a strong natural defense against wildfire, decomposition and infestation by certain insects such as termites. Tannic acid is found in the seeds, bark, cones, and heartwood.

Tannic acid is a common mordant used in the dyeing process for cellulose fibers such as cotton, often combined with alum and/or iron.
The tannin mordant should be done first as metal mordants combine well with the fiber-tannin complex.
However this use has lost considerable interest.

Similarly tannic acid can also be used as an aftertreatment to improve wash fastness properties of acid dyed polyamide.
Tannic acid is also an alternative for fluorocarbon aftertreatments to impart anti-staining properties to polyamide yarn or carpets.
However, due to economic considerations currently the only widespread use as textile auxiliary is the use as an agent to improve chlorine fastness, i.e. resistance against dye bleaching due to cleaning with hypochlorite solutions in high-end polyamide 6,6-based carpets and swimwear.
Tannic acid is, however, used in relatively small quantities for the activation of upholstery flock; this serves as an anti-static treatment.

Tannic acid is used in the conservation of ferrous (iron based) metal objects to passivate and inhibit corrosion.
Tannic acid reacts with the corrosion products to form a more stable compound, thus preventing further corrosion from taking place.
After treatment the tannic acid residue is generally left on the object so that if moisture reaches the surface the tannic acid will be rehydrated and prevent or slow any corrosion.
Tannic acid treatment for conservation is very effective and widely used but it does have a significant visual effect on the object, turning the corrosion products black and any exposed metal dark blue.
Tannic acid should also be used with care on objects with copper alloy components as the tannic acid can have a slight etching effect on these metals.

Tannic acid is also found in commercially available iron/steel corrosion treatments, such as Hammerite Kurust.

Use in food

In many parts of the world, Tannic acid's uses in food are permitted.
In the United States, tannic acid is generally recognized as safe by the Food and Drug Administration for use in baked goods and baking mixes, alcoholic and non-alcoholic beverages, frozen dairy products, soft and hard candy, meat products, and rendered animal fat.

Uses as a medication
In conjunction with magnesium and sometimes activated charcoal, tannic acid was once used as a treatment for many toxic substances, such as strychnine, mushroom, and ptomaine poisonings in the late 19th and early 20th centuries.

Tannic acid is found in the nutgalls formed by insects on the twigs of certain oak trees.
Purified tannic acid is sometimes used as medicine.

People use tannic acid for conditions such as cold sores, diaper rash, heat rash, and many others, but there is no good scientific evidence to support these uses.

In foods and beverages, tannic acid is used as a flavoring agent.

In manufacturing, tannic acid is used in ointments and suppositories; for tanning hides and manufacturing ink; and to kill dust mites on furniture.

Physical properties of tannic acid:

-The molecular formula of tannic acid is C₇₆H₅₂O₄₆.
-Tannic acid is also known as Gallotannic acid or Gallotannin.
-The molecular weight of tannic acid is 1701.2 g/mol.
-Tannic acid has a faint odour and is a light yellow to tan.
-Tannic acid exists in solid form.
-Tannic acid has a density of 2.12g/cm³.
-The solubility of tannic acid in water is 250 g/L.
-Tannic acid has an astringent taste.
-Tannic acid decomposes at 200°C.
-Tannic acid sinks and mixes with water.

2. Chemical properties of tannic acid:

-Tannic acid acts as a weak acid.
-Tannic acid molecules are unstable due to bacterial action and in the presence of oxygen and light.
-Tannic acid does not react with iron. Hence, used as a corrosion inhibitor.
-Tannic acid is insoluble in chloroform, benzene, carbon disulphide, diethyl ether, carbon tetrachloride (CCl₄), and petroleum.
-When heated, Tannic acid decomposes to emit acrid smoke and fumes.
-Tannic acid catalyses the formation of nitrosodiethylamine.
-The solution of tannic acid in glycerin is relatively stable.

The Function of Tannic Acid
-Generally, tannic acid used for pharmaceutical actions is considered pentadigalloylglucose.
Tannic acid has a severe effect.
Tannic acid is thought to exert antibacterial and antiviral effects.

When used internally, Tannic acid dehydrates tissues and causes a reduction in secretions.
Externally, Tannic acid works by forming a protective layer of constricted and harder cells.

The main actions of tannic acid are because of its local effects.
After ingestion, Tannic acid shows a high affinity to plasma proteins, poor bioavailability because of its large size, and low lipid solubility.

What Is Tannic Acid Used For?
The following list below aids you in answering the question of what is tannic acid used for.

-Tannic acid has wide use in the food industry.
Mostly it is operated to improve the clarity and taste of drinks.
-Tannic acid does not contain any E number, which makes it a natural additive.
Hence, Tannic acid is highly used in beers, wine, and soft drinks.
-Because Tannic acid produces dark natural colours, it is often used in wood stains.
-The dark colours of tannic acid assist in imitating light woods, the properties of dark ones.
-It is employed as aesthetic ether.
-The Sequoia redwoods use tannic acid and similar chemicals to protect against insects and wildfire.
Otherwise, these things would eat into Sequoia’s heartwood.
-Tannic acid is applied topically to treat diaper rash, cold sores, poison ivy, and fever blisters.
-Tannic acid is used in both forms, i.e., orally and as ointments.
-In history, tannic acid was used as an antidote against different poisons.
-Tannic acid is applied for chronic diarrhoea, bleeding, bloody urine, dysentery, persistent coughs, painful joints, and cancer.
-Tannic acid can create a more stable form of oxidation layer on metals to stop rust from eating through the metal.
-Tannic acid is operated in textiles to help colours stay fast when dyed, rendering fabrics stain-resistant.

Quercitannic and gallotannic acids
Quercitannic acid is one of the two forms of tannic acid found in oak bark and leaves.
The other form is called gallotannic acid and is found in oak galls.

The quercitannic acid molecule is also present in quercitron, a yellow dye obtained from the bark of the Eastern black oak (Quercus velutina), a forest tree indigenous in North America.
It is described as a yellowish-brown amorphous powder.

In 1838, Jöns Jacob Berzelius wrote that quercitannate is used to dissolve morphine.

In 1865 in the fifth volume of "A dictionary of chemistry", Henry Watts wrote :

It exhibits with ferric salts the same reactions as gallotannic acid.
It differs however from the latter in not being convertible into gallic acid, and not yielding pyrogallic acid by dry distillation.
It is precipitated by sulfuric acid in red flocks.
According to Rochleder, the tannic acid of black tea is the same as that of oak-bark.

In 1880, Etti gave for it the molecular formula C17H16O9.
He described it as an unstable substance, having a tendency to give off water to form anhydrides (called phlobaphenes), one of which is called oak-red (C34H30O17).
For him, it was not a glycoside.

An electrostatic potential map (blue is positive and red is negative charge) of decagalloyl tannic acid, i.e. a tannic acid derived from ten molecules of gallic acid
In Allen's "Commercial Organic Analysis", published in 1912, the formula given was C19H16O10.

Other authors gave other molecular formulas like C28H26O15, while another formula found is C28H24O11.

According to Lowe, two forms of the principle exist – "one soluble in water, of the formula C28H28O14, and the other scarcely soluble, C28H24O12.
Both are changed by the loss of water into oak red, C28H22O11."

Quercitannic acid was for a time a standard used to assess the phenolic content in spices, given as quercitannic acid equivalent.

SYNONYMS:

72401-53-7
Gallotannic acid
CHEBI:75211
Gallotannin
Glycerite
Tannicum acidum
Acid, tannic
Tannic Acid, A
Tannic acid (TN)
D-Glucopyranose, 1,2,3,4,6-pentakis(3,4-dihydroxy-5-((3,4,5-trihydroxybenzoyl)oxy)benzoate)
D-Glucopyranose, pentakis(3,4-dihydroxy-5-((3,4,5-trihydroxybenzoyl)oxy)benzoate)
D-Glucopyranose, pentakis[3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoate]
28F9E0DJY6
acido tanico
NSC656273
NSC-656273
NSC-758670
1,2,3,4,6-pentakis-O-(3,4-dihydroxy-5-((3,4,5-trihydroxybenzoyl)oxy)benzoyl)-D-glucopyranose
1,2,3,4,6-pentakis-O-{3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoyl}-D-glucopyranose
D-Glucopyranose, 1,2,3,4,6-pentakis[3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoate]
EINECS 276-638-0
TANNIC ACID, ACS
Tannic acid (JP16/USP)
TANNIC ACID (USP-RS)
DTXSID2026076
SCHEMBL13287055
DTXSID50888153
TANNIC ACID (EP IMPURITY)
TANNIC ACID (EP MONOGRAPH)
HY-B2136
NSC 5031
TANNIC ACID (USP MONOGRAPH)
DEPINAR COMPONENT TANNIC ACID
AKOS015896071
OC-108 COMPONENT TANNIC ACID
CS-7817
DB09372
TANNIC ACID COMPONENT OF DEPINAR
EN300-28266021
D-Glucose pentakis(3,4-dihydroxy-5-((trihydroxy-3,4,5-benzoyl)oxy)benzoate)
1,2,3,4,6-penta-O-{3,4-dihydroxy-5-[(3,4,5-trihydroxybenzoyl)oxy]benzoyl}-d-glucopyranose
2,3-dihydroxy-5-({[(2R,3R,4S,5R)-3,4,5,6-tetrakis[3,4-dihydroxy-5-(3,4,5-trihydroxybenzoyloxy)benzoyloxy]oxan-2-yl]methoxy}carbonyl)phenyl 3,4,5-trihydroxybenzoate
2,3-dihydroxy-5-({[(2R,3R,4S,5R,6R)-3,4,5,6-tetrakis({3,4-dihydroxy-5-[(3,4,5-trihydroxyphenyl)carbonyloxy]phenyl}carbonyloxy)oxan-2-yl]methoxy}carbonyl)phenyl 3,4,5-trihydroxybenzoate