Tannic acid

Tannic acid has its structure still remain unclear, and is generally considered to be the ester formed by the five hydroxyl groups of glucose and gallic acid acyl group. The industrial tannic aicd can be obtained by the extraction of Gallic and further concentration. After further purification, we can obtain pharmaceutical or reagent tannic acid.
Tannic acid is a pale yellow amorphous powder or shiny scaly-like or sponge-like solid. It has no special smell with bitter taste and convergence. It can be gradually darken upon exposure to air and sunlight. It is soluble in cold water and even infinitely soluble in hot water; it is also soluble in methanol, ethanol, acetone and ethyl acetate but insoluble in benzene, ether, chloroform, petroleum ether and carbon disulfide. The aqueous solution of tannic acid exhibits weak acidic and is easily oxidized with oxidation rate being faster in alkaline solution and the color of the solution being deeper. In coming across trivalent iron ions, the solution exhibits blue-black color and can react with gelatin, alkaloids to generate precipitate. It can also react with metal ions such as lead, aluminum, and zinc to generate poly-nuclear complexes and insoluble salts with special colors. When being heated to 210~215 ℃, tannic acid can be decomposed into pyrogallic acid and CO2. Tannic acid has low toxicity, but high intake of it can cause vomiting, abdominal pain, diarrhea, and can also lead to circulatory system disorder which is lethal, LD100 6.0 g/kg (rat, orally). At high temperature, it can be decomposed to generate pyrogallol and carbon dioxide. Market selling tannic acid usually contains 10% moisture.

Figure 1 is the chemical structural formula of tannic acid

In AD 734 (Tang Kaiyuan period year 22th), Cangqi Chen has already listed Gallic into the pharmacopoeia "Herbal Supplements”. In Ming Dynasty, Gallic had also been described in the book "Compendium of Materia Medica" written by Shizhen Li. In 1862, Gallic has also been transferred to Europe. In 1887, S.Mierzinski has used Chinese Gallic for extracting tannin acid for tanning. In 1936, Fuhua Li et al had also written paper to introduce the Chinese Gallic and its utilization status. Around 1940s, YanBing Wu, Wende Wei, and Xinfang Fang (Chinese Yellow Sea Chemical Industries, Ltd.) had studied the approach of extracting tannin and gallic acid fermentation from Gallic. Over the same period, it had also been set up of plants in Shanghai and Chongqing for production of tannic acid and gallic acid. In 1957, Shanghai “RenJi” chemical factory was moved to production area of Gallic, Guizhou for the construction of a second chemical plants in ZunYi City to continue the production. In 1988, people in Hubei had applied new technology and new equipment and established a modern tannic acid plant in Zhushan. There were also several small-scale tannins workshop in Henan, Shaanxi, Hunan, and Yunnan province with the annual national production capacity of tannic acid plant (workshop) being about 3,000 tons.
Since the 1830s, Turkey, Peru and Venezuela had successively utilized Turkey gallnut (also known as staining oak gallnut) and tara pods for producing tannic acid or gallic acid. There are still processing and utilization in current time.
The above information is edited by the chemicalbook of Dai Xiongfeng.

Gallic is caused by some aphid parasites of Pemphigidae. They have their parasitism life in the leaves of some plant Anacardiaceae Rhus chinensis. When the host tender tissues are subjecting the mechanical and chemical stimuli of aphid, they exhibit abnormal growth with swelling into irregular circle-shaped, spindle-shaped, cystic gall body with horn-shaped protuberance or flowery appearance. During the parasitism process of aphid, on one hand it gets the nutrient from the host plants while secreting saliva containing a large amount of enzymes which enters into the cambium from sting area, so the cellular metabolism nearby get enhanced which stimulates the meristem of cells. Inside the gall, aphid constantly proliferates and eating with the gall body continuously bloating. During the initial phase, there is only one aphid inside the gall, after several generations of breeding, the number dramatically increases. Upon the last generation, winged aphids emerge, shell bursts and the aphid flies outside the gall body and migrates to the winter host plant (moss type plant) for winter. In the next year, it flies back into the living host tree Rhus chinensis for breeding again with re-formation of Gallic.
The indispensible conditions for production of gallic include: there are ecological environment suitable for the normal growth and reproduction of gall aphids, summer host plant and winter host moss. Moreover, all the three components including gall aphids, summer host plant and winter moss should be available. In the ecological environment, the climate plays an important role in the gallic production. The climate properties of Gallic areas is mild climate, abundant rainfall, abundant rainy days and more clouds, less sunlight, great humidity with no dry seasons or no obvious dry seasons throughout the whole year.
Although there are 10 kinds of gallic, but those which majorly used for the production or export are angular gallic and belly gallic of high production. Angular gallic is mainly produced in the south area of the Yangtze river with the production amount accounting for about 85% of total production in the production area. The north area of the Yangtze River and south area of the Qinling Mountains are the major production area for belly gallic with its output accounting for about 80% of total production. In the total output of the commercialized gallic, the angular gallic can account for about 80% while the belly gallic accounting 15% and the gallic flowers accounting for about 5%.
The main components of gallic is the gallic tannin, accounting for about 73%, in addition, it contains a small amount of cellulose, lignin, starch, pectin, and pentosan. Among the gallic tannin, tannin accounts for about 70% with gallic acid accounting for about 21%, tri-gallic acid accounting for about 1%, the rest is five times acyl glucose. Gallic is mainly used as the raw material for the production of industrial tannic acid, medicine tannic acid, gallic acid and Pyrogallic acid.

Figure 2 the picture of the gallic plant

Tannic acid is mainly used as dyeing mordant and also used for the preparation of gallic acid, gallic acid pyrophosphate. It can also be used for making leather tanning agents, rubber coagulant, proteins and alkaloids precipitant as well as the reagent for the determination of beryllium, aluminum, nickel, and copper.
The light-yellow to light brown amorphous powder obtained by the evaporation and drying of the water extract of the gallic is the industrial tannic acid with the content of tannic acid being more than 80%. It also contains a small amount of gallic acid, m-gallic acid, tris gallic acid and pentagalloylglucose.
Tannic acid has the 1, 3, 4, 6-tetra-O-galloyl-2-multi-O-galloyl-β-D-glucose as the core and is the ester formed by the combination between one glucose molecule and 8 to 9 gallic acid. Tannic acid is susceptible to acid or enzymatic hydrolysis with the hydrolyzate being gallic acid and glucose.
The major applications of the industrial tannic acid are as follows:
1. As the raw material of gallic acid and gallic acid pyrophosphate.
2. Mordant. For fiber fixing or staining, as the basic dyes of salt.
3. Ore flotation agent. It can be used for the smelting of the rare metal, extracting the germanium from the dust or the lead-zinc, extraction of rare metals such as thorium, polonium from solution, and extraction of lead and cooper from chalcopyrite.
4. Conversion coating. It can be used for the surface anti-corrosion of aluminum and its alloy plate, steel, copper, and zinc.
5. Food additives such as food antioxidants, beverage clarifying agent, advanced ink and the printing ink.
6. The thinner of drilling mud.
7. It can be used as a kind of synergist. It can be applied to the synthesis of 2, 4-Diamino-5-trimethoprimam, referred as TMP or sulfa synergist.
8. Deodorant. It can be used in refrigerators, warehouses, and toilet to get rid of the ammonia odor. In addition, tannic acid may also be used for synthesis of heart disease drugs such as hexobendine and dilazep; it can also be used for the synthesis of bifendate, treatment of hepatitis B; synthesis of antimony-273; treatment of schistosomiasis.
Tannic acid can inhibit the growth of bacteria and intestinal absorption of toxins. It can be used for prevention and treatment of diarrhea. Medicinal tannic acid can be directly used in beverages, frozen products, candy, ice cream, meat products; as the astringents of burn wounds; stomach hemostatic agents; prevention of infection; it can be made into tannic acid glycerol, tannic acid protein, tannic acid ointments, anti-fever agent (N-bis-amidino morpholino tannic acid), health promotion agent, insect repellents, pesticides, radiation protection agents, contraceptive agents and special-effect toothpaste.

In 1985 the US Food and Drug Administration had listed tannic acid as “general recognized as safe” (GRAS), meaning that it is not harmful or dangerous. It can be used in pharmaceutical, cosmetic preparation; as the ingredients as food such as frozen dairy products, meat products or drinks such as soft drinks, tea, wine ingredients.

Figure 3 is the reference quality standards of industry tannic acid and pharmaceutical tannic acid

It is suitable for tanning harness leather, sole leather and sheepskin. It is recommended to store it in a cool, dry, ventilated warehouse. It is better to be used in combination with other tanning agents.
It is mainly used for tanning. It can also be applied to the medicine, ink, printing, rubber and metallurgical industries as well as water treatment, etc.
It can be used for tanning, fishing net dyeing, boiler cleaning, drilling, etc.
It can be used as analysis reagents as well as applied to the pharmaceutical industry.
It can be used for the pH adjusting of pelt pickling and vegetable tanning solution. It can be used for vegetable tanning rinse. Owing to its strong acidity, we shouldn’t pack it in iron containers. It should be stored in a cool warehouse.
It can be used as a water-base drilling viscosity reducer and cement retarder.
In pharmaceutical industry, it can be used as the raw material for the preparation of gallic acid, pyrogallol and sulfa drugs. Tannin is a kind of hemostatic drug. In the field of medicine, it has ever been used for treating pharyngitis, tonsillitis, hemorrhoids and skin blistering disorders, internal application can curb diarrhea and intestinal hemorrhage. Tannin can react with metals, alkaloids and glycosides, etc to form precipitate with detoxification effect against these substances. Tannin can be used for leather tanning, manufacture of ink, paper and silk glue, boiler cleaning etc., it can also be used as mordent, the clarifying agent of beer and wine as well as the coagulant agent of rubber as well as reagents for the determination of beryllium, aluminum, nickel and copper. In the field of chemical production, it can be used for preparing gallic acid and gallic acid pyrophosphate. Tannin is used for dilution when dealing with the mud drilling. Mix the tannin powder in proportion with caustic soda can yield tannins alkaline solution which can reduce the shearing force of thickening mud and sticky mud, improving the flow of mud. On the contrary, if the tannin powder was added directly to the mud, due to its weak acidicity, the pH of the mud is reduced. Through the ion exchange with the clay particles, it reduces the hydration of the surface of the clay particle, leading to the formation of the network structure of the clay particles, improving the mud shearing force and viscosity. According to the provision of the GB2760-89 of China, "curing tannins" can be used for low degree wine and wine, as a clarifying agent for removing protein in its turbidity state and other suspended substances. In the food industry, it can also be used as astringent agents and crude oil deodorizer.
It can be used for the precipitation and weight determination of beryllium, aluminum, gallium, indium, niobium, tantalum and zirconium. It can also be used for the colorimetric assay of copper, iron, vanadium, cerium and cobalt. It can be used as the precipitating reagents of proteins and alkaloids. It can also be used as the external indicator in the titration of lead using molybdate.

Tannin is presented in the bark and fruit of a variety of trees (such as oak and sumac) and is also the main component of the gall formed when the trees are also subject to attack by insects with the content being 50-70%. Crush the gallic, remove the dead insects and insect droppings and other impurities, put into the copper or wood extraction tank and extract with soft water; the extract was concentrated under reduced pressure, add a small amount of ether, apply spray drying so that the light tannin is obtained. Medicinal tannic acid is produced through extracting the concentrated solution with ether with the extract being bleached by sodium bisulfite and further recovery of ether to obtain the final medicine tannin.
Crush the Gallic, screen, and then impregnate with water, put the immersed water for clarification and preheating, and then spray-drying with refined powder sieved to obtain the final products.
Throw 100 kg of refined naphthalene into the sulfonated kettle, heat to 125 ℃, add 120 kg of concentrated sulfuric acid under stirring and have reaction at 155~165 ℃ for 6~8h. Apply sampling and determine the end point, if it is completely soluble in water, the sulfonation completes. Gradually cool to 110 ℃, dilute with a small amount of water. At about 80 ℃, the material liquid was compressed into the condensation tank. At about 70 ℃, add drop wise of 39 kg of 37% aqueous solution of formaldehyde, and after completion of the dropping, have reaction at 80~90 ℃ for 3 h to obtain the black viscous liquid which is the finished product.
The larch bark is crushed, extracted, purified, concentrated and dried to obtain the finished product.

toxic substances

highly toxic

intraperitoneal-mouse LD50: 150 mg/kg; intravenous-mouse LD50: 50 mg/kg

thermal decomposition yields acrid smoke

warehouse: low-temperature, dry and ventilated

Water, carbon dioxide, foam, powder

Tannic acid is a naturally occurring plant polyphenol and can be found in practically all aerial plant tissues. Tannic acid was historically used for the treatment of diarrhea, topically to dress skin burns and rectally for treatment of unspecified rectal disorders. Pharmaceutical use of tannic acid is discontinued due to safer and better alternatives.
An unusually high incidence of esophageal cancer has been noted in areas of South Africa, where a sorghum rich in tannins is consumed. A positive relation has been observed between the tannin content of the sorghum and the incidence of esophageal cancer.

Quebracho, an evergreen tree 15 to 18 m (49 to 59 ft) tall, grows abundantly throughout South America (Argentina, in particular). The Argentine variety is characterized by its bright-red bark, rich in tannin, used for dyeing. The part used is the bark (from either the trunk or branches). Quebracho is tonic, aromatic.

Tannic acid or hydrolysable gallotannin is a complex polyphenolic organic structure that yields gallic acid and either glucose or quinic acid as hydrolysis products. Tannic acid is odorless or has a faint, characteristic odor and an astringent taste.

Tannic acid, C₁₄H₁₀O₉, also known as digallic acid, tannin, and gallotannin, is a yellowish powder that decomposes at 210°C (410°F). Tannic acid is derived from nutgalls. It is soluble in water and alcohol,and is insoluble in acetone and ether. Tannic acid is used in tanning,textiles, and as an alcohol denaturant. An amorphous form of tannic acid, also known as pentadigalloylglucose, exists with the formula C₇₆H₅₂O₄₆. It is a yellowish to brownish powder that is very soluble in alcohol and ether.It also decomposes between 210 and 215°C (410 and 419 °F). This form is used to clarify wine or beer, as a reagent,and as a mordant in dyeing.

Reported found in Quercus oliver and related species; Tara (Caesalpinia spinosa); and various sumac species, including Rhus semialata, R. coriaria, R. glabra and R. typhia.

Tannic Acid is a sequestrant that refers to a mixture of hydrolyzable tannins of a more complex structure than gallic acid. it is used in clarifying beer and wine. see tannins.

nonspecific enzyme/receptor blocker

Tannic acid is a powder extracted from gall nuts that is soluble in water but less so in alcohol. Tannic acid was used by Major Russell in the mid-1850s for the tannin process of preparing dry collodion plates. The collodion plate was coated and sensitized as usual but the excess silver was then washed completely from the surface. A solution of tannic acid was then poured on and off the plate and the collodion film allowed to dry completely in the dark. The tannin plate could be preserved for months prior to exposure. The exposed plate was developed in pyrogallic acid, citric acid, and silver nitrate to replace that which was washed off during the initial preparation. The exposures required for tannin plates were as much as five times longer than wet collodion plates, which made them suitable only for landscape work.

Tannic acids are phenolic compounds that have several hydrolyzable groups. They are classified as (a) hydrolyzable, yielding phenols such as gallic acid in the presence of acid and heat; and (b) condensed, obtained from the extract of oak trees and not hydrolyzable. Tannic acids are used for taste and chemical properties and as a sequestrant. They affect the color and flavor of fruits and vegetables. They are used in fruits, wine, and beer to remove undesirable material by forming insoluble complexes with the proteins.

Clarifying agent; pH control

ChEBI: 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 is obtained by solvent extraction from the nutgalls or the excrescences that form on the young twigs of Quercus olivier and allied species of Quercus L.; from the seed pods of Tara (Caesalpinia spinosa); or from the nutgalls of various sumac species, including Rhus semialata, R. coriaria, R. glabra and R. typhia.

tannic acid: A yellowish complexorganic compound present in certainplants. It is used in dyeing as a mordant.

Main constituents include three crystalline alkaloids—aspidospermine, quebrachine and quebrachamine (chemically identical to yohimbine)—responsible for the tonic and antispasmodic physiological action. A. quebrachoblanco bark contains 0.3 to 1.5% alkaloids (aspidospermine 30%, quebrachine 10%, deacetylaspidospermine 5%, aspidospermatidine 3%, 1-methylaspidospermatidine 0.5%, quebrachimine and quebrachit). Leaves contain rhazinilam (lactam).

Light yellow to tan solid with a faint odor. Sinks and mixes with water.

Water soluble. Gradually darkens on exposure to air and/or light

Glycerite decomposes at 210° to carbon dioxide and pyrogallol, which can form irritating vapors [USCG, 1999]. Incompatible with salts of heavy metals, alkaloids, gelatin, albumin, starch, oxidizing substances-e.g., permanganates, chlorates; lime water [Merck].

Toxic by ingestion and inhalation. Questionable carcinogen.

Inhalation causes irritation of nose and throat, coughing, and sneezing. Ingestion may cause gastric disturbance. Contact with eyes causes irritation.

Special Hazards of Combustion Products: Decomposes at 210° to carbon dioxide and pyrogallol, which can form irritating vapors.

Quebracho is the most common tannic acid derivative widely used in flotation. The main phenolic nuclei present in Quebracho are resorcinol/phloroglucinol and catechol/pyrogallol.
Quebracho is commercially available in the following three forms: (a) standard Quebracho, a direct hot-water extract from the heart-wood with adjusted pH (Qu–O), (b) sulfited Quebracho, in which sulfonic acid groups have been introduced (Qu–S) and (c) aminated Quebracho (Qu–A), where amine groups are introduced to ordinary Quebracho, rendering the polymer amphoteric (iso-electric point at pH 7). Each of these types of Quebracho has a different depressing effect.

Tannins, an astringent organic compound, are toxic to many microorganisms due toinhibition of oxidative phosphorylation (Scalbert 1991). It is responsible for thepuckering feeling in the human mouth following the consumption of unripe fruits ortea (Vidal et al. 2004). Pomegranates (Punica granatum) have been widely studiedfor their potent antioxidants, which include ellegitannin, elegiac acid, and punicalagin,which are commonly known for their anti-proliferative and apoptotic effects oncolon cancer cell lines (Seeram et al. 2005). Herbs such as cloves (Syzygium aromaticum)can also play important role in preventing and treating some cancers.Cervical, breast, prostate, and oesophageal cancer cells were killed within 24 h afterthe application of clove oil (Dwivedi et al. 2011). It was also found effective in treatinglung cancer by means of in situ cell proliferation (Banerjee et al. 2006). Tarragon(Artemisia dracunculus) extract is indicated as cytotoxic to breast cancer thoughregulation of certain proteins that induce apoptosis (Obolskiy et al. 2011). Tarragonalso contains potent compounds such as sakuranetin and 6-methoxycapilliarisin thatappear to have anticancer effects on oesophageal cancer by inducing DNA damagein the cancerous cells (Hong and Ying 2015). Cumin (Cuminum cyminum) has beenused since ancient times, and some studies have shown it to have a cytotoxic effectto colorectal cancer cell lines (Prakash and Gupta 2014; Al-Snafi 2016). Thyme(Thymus vulgaris) essential oil has been claimed to demonstrate cytotoxic activity on head and neck squamous cell carcinomas by interrupting reproduction at the transcriptionallevel of cancer cells, with effects such as interfering in N-glycan biosynthesisand extracellular signal-regulated kinase 5 signalling (Sertel et al. 2011).Cinnamon (Cinnamomum sp.) is most commonly known as culinary spice, yet it isalso used for its medicinal properties in treating gastrointestinal sickness. Cinnamonbark extract was evaluated for anticancer ability, and it was found to induce apoptosisin HepG2 cells (liver cancer cells) after 24 h at certain dosages (Varalakshmiet al. 2014). An extract of cinnamon, 2′-hydroxycinnamaldehyde, shows severalantitumour effects on oral cancer cell lines; this is demonstrated by anti-proliferativeactivity of apoptotic cells and inhibition of tumour mass growth (Kim et al. 2010).

Poison by intravenous and intraperitoneal routes. Questionable carcinogen with experimental tumorigenic data. When heated to decomposition it emits acrid smoke and irritating fumes.

Tannic acid is synthesized by extraction from Nutgalls (Chinese or Turkish), Myrobalans (Terminalia SP.), Oakbark, etc. It is also synthesized by esterification of Glucose with meta-galloylgallic acid.

Tannins and tannic acid occur naturally in plants. Essentially all wood and plant tissue contain tannins. Therefore, biodegradation is expected to be the major environmental fate process for tannic acid.

Tannic acid causes centrilobular liver necrosis following absorption from gastrointestinal tract, mucus membranes, or denuded skin surfaces. Liver metabolism of tannic acid requires methyl-group donors. Therefore, methyl-group donors can be depleted following excessive tannic acid absorption.