Names | |
---|---|
Other names Quercitannin Oak bark tannin Quercotannic acid Querci-tannic acid Querco-tannic acid | |
Identifiers | |
Properties | |
several, see text | |
Appearance | yellowish brown amorphous substance |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Quercitannic acid is one of the two forms of tannic acid [1] found in oak bark and leaves. [2] 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 substance. [3]
In 1838, Jöns Jacob Berzelius wrote that quercitannate is used to dissolve morphine. [4]
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. (Stenhouse, Ann. Ch. Pharm. xlv. 16.)
According to Rochleder (ibid lxiii. 202), the tannic acid of black tea is the same as that of oak-bark. [5]
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. [6] [7]
In Allen’s "Commercial Organic Analysis", published in 1912, the formula given was C19H16O10. [8]
Other authors gave other molecular formulas like C28H26O15, while another formula found is C28H24O11. [9]
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. [10]
Quercitannic acid was for a time a standard used to assess the phenolic content in spices, given as quercitannic acid equivalent. [11]
Salicylic acid is an organic compound with the formula HOC6H4CO2H. A colorless, bitter-tasting solid, it is a precursor to and a metabolite of aspirin (acetylsalicylic acid). It is a plant hormone, and has been listed by the EPA Toxic Substances Control Act (TSCA) Chemical Substance Inventory as an experimental teratogen. The name is from Latin salix for willow tree. It is an ingredient in some anti-acne products. Salts and esters of salicylic acid are known as salicylates.
Tannins are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
Cystine is the oxidized derivative of the amino acid cysteine and has the formula (SCH2CH(NH2)CO2H)2. It is a white solid that is poorly soluble in water. As a residue in proteins, cystine serves two functions: a site of redox reactions and a mechanical linkage that allows proteins to retain their three-dimensional structure.
Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6H2(OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. It is a white solid, although samples are typically brown owing to partial oxidation. Salts and esters of gallic acid are termed "gallates".
Oxalic acid is an organic acid with the systematic name ethanedioic acid and formula HO2C−CO2H. It is the simplest dicarboxylic acid. It is a white crystalline solid that forms a colorless solution in water. Its name comes from the fact that early investigators isolated oxalic acid from flowering plants of the genus Oxalis, commonly known as wood-sorrels. It occurs naturally in many foods. Excessive ingestion of oxalic acid or prolonged skin contact can be dangerous.
Iron gall ink is a purple-black or brown-black ink made from iron salts and tannic acids from vegetable sources. It was the standard ink formulation used in Europe for the 1400-year period between the 5th and 19th centuries, remained in widespread use well into the 20th century, and is still sold today.
Tannic acid is a specific form of tannin, a type of polyphenol. Its 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. Commercial tannic acid is usually extracted from any of the following plant parts: Tara pods (Caesalpinia spinosa), gallnuts from Rhus semialata or Quercus infectoria or Sicilian sumac leaves (Rhus coriaria).
Quercitron is a yellow natural dye obtained from the bark of the Eastern Black Oak, a forest tree indigenous in North America. It was formerly called Dutch pink, English pink, or Italian pink.
Bdellium is a semi-transparent oleo-gum resin extracted from Commiphora wightii plants of India, and from Commiphora africana trees growing in sub-saharan Africa. According to Pliny the best quality came from Bactria. Other named sources for the resin are India, Arabia, Media, and Babylon.
Ellagic acid is a polyphenol found in numerous fruits and vegetables. It is the dilactone of hexahydroxydiphenic acid.
Phosphorus pentasulfide is the inorganic compound with the formula P2S5 (monomer) or P4S10 (dimer). This yellow solid is the one of two phosphorus sulfides of commercial value. Samples often appear greenish-gray due to impurities. It is soluble in carbon disulfide but reacts with many other solvents such as alcohols, DMSO, and DMF.
Triethyloxonium tetrafluoroborate is the organic oxonium compound with the formula [(CH3CH2)3O]BF4. It is often called Meerwein's reagent or Meerwein's salt after its discoverer Hans Meerwein. Also well known and commercially available is the related trimethyloxonium tetrafluoroborate. The compounds are white solids that dissolve in polar organic solvents. They are strong alkylating agents. Aside from the BF−
4 salt, many related derivatives are available.
Fluoroboric acid or tetrafluoroboric acid (archaically, fluoboric acid) is an inorganic compound with the chemical formula [H+][BF4−], where H+ represents the solvated proton. The solvent can be any suitably Lewis-basic entity. For instance, in water, it can be represented by H
3OBF
4 (oxonium tetrafluoroborate), although more realistically, several water molecules solvate the proton: [H(H2O)n+][BF4−]. The ethyl ether solvate is also commercially available: [H(Et2O)n+][BF4−], where n is most likely 2. Unlike other strong acids like H2SO4 or HClO4, the pure unsolvated substance does not exist (see below).
Perazine (Taxilan) is a moderate-potency typical antipsychotic of the phenothiazine class. It is quite similar to chlorpromazine, and acts as a dopamine antagonist. A 2014 systematic review compared it with other antipsychotic drugs:
Phlobaphenes are reddish, alcohol-soluble and water-insoluble phenolic substances. They can be extracted from plants, or be the result from treatment of tannin extracts with mineral acids. The name phlobaphen come from the Greek roots φλoιὀς (phloios) meaning bark and βαφή (baphe) meaning dye.
Octahydroxyanthraquinone is an organic compound with formula C
14H
8O
12, formally derived from anthraquinone by replacement of 8 hydrogen atoms by hydroxyl groups.
A hydrolyzable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids.
Quercus infectoria or the Aleppo oak is a species of oak well known for producing galls that have been traditionally used for centuries in Asia medicinally while also used in softening leather and in making black dye and ink.
Sodium orthosilicate is the chemical compound with the molecular formula Na
4SiO
4. It is one of the sodium silicates, specifically an orthosilicate, formally a salt of the unstable orthosilicic acid H
4SiO
4.
Taraxacin is a guaianolide with the molecular formula C15H14O3 which has been isolated from the plant Taraxacum officinale. Taraxacin has a bitter taste. Taraxacin has diuretic properties.