Tannic acid: Difference between revisions

| ImageSize = 200px

| KEGG ChEBI = 75211

| Formula = |C=76 | H=52 | O=46 |

| Density = 2.12g/cm³

| MeltingPt = decomposes above 200  °C

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| Section7 = {{Chembox Hazards

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| NFPA- O S =

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| SPhrases PPhrases =

| RSPhrases GHS_ref =

| Autoignition AutoignitionPt =

| PEL =
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[[ Image File:Bottle of tannic acid.jpg|thumb |right|A bottle of tannic acid (water solution) from the [[redwood tree]].]]

'''Tannic acid''' is a specific commercial form of [[tannin]], a type of [[polyphenol]]. Its weak [[acidity]] ([[Acid dissociation constant|pK_a]] 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 [[gallic acid|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 part parts: Tara pods (''[[Caesalpinia spinosa]]''), gallnuts from ''[[Rhus semialata]]'' or ''[[Quercus infectoria]]'' or Sicilian Sumac sumac leaves (''[[Rhus coriaria]]'').

According to the definitions provided in external references such as international pharmacopoeia, [[Food Chemical Chemicals Codex ]] and FAO-WHO tannic acid monograph only tannins sourced 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. It is a yellow to light brown [[amorphous]] powder which is highly soluble in water; one [[gram]] dissolves in 0.35 [[millilitre|mL]] of water.

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 have has compounded the confusion. This is particularly widespread in relation to green tea and black tea . , Although both tea of contains which tannin contain and many various different types of polyphenols, tannins "contrary not to just widespread belief, tea does not contain exclusively tannic acid. "<ref>{{cite journal | author doi= Hamilton-Miller JM 10.1126/science.432625 |title= Antimicrobial Darvon properties safety of |year=1979 tea |last1=Pettinga (''Camellia sinensis L |first1=C. '') |journal= Antimicrob. Agents Chemother. Science |volume= 39 204 |issue= 11 4388 |pages= 2375–7 6 |date=1 November 1995|pmid= 8585711 432625 | pmc bibcode= 162950 |url=http://aac 1979Sci. asm. org/cgi/pmidlookup?view=long&pmid=8585711 .204....6P}}</ref>

In 1838, [[Jöns Jacob Berzelius]] wrote that quercitannate is used to dissolve morphine.<ref>Traité de chimie, Volume 2. Jöns Jakob Berzelius (friherre) and Olof Gustaf Öngren, A. Wahlen et Cie., 1838 {{page needed|date=December 2013}}</ref>

<blockquote>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. ([[John Stenhouse|Stenhouse]], Ann. Ch. Pharm. xlv. 16.)

<br>According to Rochleder (ibid lxiii. 202), the tannic acid of black tea is the same as that of oak-bark.<ref> {{cite book|url = https://books.google.com/books?id=J9fokzIF4NMC&pg=PA6 |title =A dictionary Dictionary of chemistry , Volume and the allied branches of other sciences|volume= 5 , |first by = Henry |last = Watts |date = 1868|publisher = Longmans, 1865 Green, and Company|page = 6}}</ref></blockquote>

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 [[anhydride]]s (called [[phlobaphene]]s), one of which is called ''oak-red'' (C₃₄H₃₀O₁₇). For him, it was not a glycoside.<ref> {{cite journal |doi=10.1007/BF01517069 |title=Über die Gerbsäure der Eichenrinde . C. |trans-title=About the tannic acid from oak bark |language=de |year=1880 |last1=Etti , |first1=C. |journal=Monatshefte für Chemie , Volume |volume=1 , Number |issue=1 , 262-278, |pages=262–78|s2cid=94578197 1880 {{doi| 10 url=https://zenodo. 1007 org/ BF01517069 record/1938533}} (German)</ref><ref> {{cite journal |doi=10.1007/BF01517990 |title=Zur Geschichte der Eichenrindegerbsäuren . C. |trans-title=On the history of oak bark tannins |language=de |year=1883 |last1=Etti , |first1=C. |journal=Monatshefte für Chemie , Volume |volume=4 , Number |issue=1 , 512-530, |pages=512–30|s2cid=105109992 1883 {{doi| 10 url=https://zenodo. 1007 org/ BF01517990 record/2518525}} (German)</ref>

According Other to authors Lowe, gave two other forms molecular of formulas the principle exist - one soluble in water, of the formula like C₂₈H_{28 26}O_{14 15}, and while the another other formula scarcely found soluble, is C₂₈H₂₄O₁₂. Both are changed by the loss of water into oak red, C₂₈H₂₂O₁₁.<ref> [ {{cite book |url=http:// www envstudies. swsbm brown. com edu/ SayreMM theses/ Sayre's_Materia_Medica-1 98RECKORD.pdf A |title=What manual are of organic materia the medica historic and pharmacognosy contemporary - ethnobotanical An introduction to the study uses of the native vegetable Rhode Kingdom Island and wetlands the plants? vegetable |first=Courtney and |last=Reckford animal |year=1997 drugs (Sayre's Materia Medica) fourth edition , |type=MA by Thesis Lucius |oclc=549678548}}{{page E needed|date=December Sayre] 2013}}</ref>

Similarly tannic acid can also be used as an aftertreatment to improve wash fastness properties of acid dyed [[polyamide]]. It is also an alternative for fluorcarbon [[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 . It is, however, used in relatively small quantities for the activation of [[upholstery]] flock; this serves as an anti-[[Static electricity|static]] treatment.

===Use in food ===

The introduction of tannic acid treatment of severe burn injuries in the 1920's 1920s significantly reduced mortality rates .<ref> {{cite S.B.A. journal Halkens |last1= et al., " |title=The use of tannic acid in the local treatment of burn wounds: intriguing old and new perspectives .", |journal=Wounds , |year=2001 , |volume=13 ( |issue=4 ), p |pages=144–58 144-158 |url=http://taninos. tripod.com/usotaninos.htm}}</ref> During [[World War II I]], tannic acid dressings were prescribed to treat "burns, whether caused by incendiary bombs, [[mustard gas]] , or [[lewisite]] ". .. Where tannic acid is not available, strong, lukewarm tea is a good substitute."<ref>{{cite news |title=Medicine: War Wounds |magazine=TIME |date=18 September 1939|url=http://www.time.com/time/magazine/article/0,9171,762600-2,00.html |archive-url= https://web.archive.org/web/20080530022321/http://www.time.com/time/magazine/article/0,9171,762600-2,00.html |url-status=dead |archive-date=May 30, 2008}}</ref> After the war this use was abandoned due to the development of more modern treatment regimes regimens.

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[[Category: Tannins Gallotannins]]