Tartaric acid
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Tartaric acid is a white crystalline organic acid. It occurs naturally in many plants, particularly grapes and tamarinds, and is one of the main acids found in wine. It is added to other foods to give a sour taste, and is used as an antioxidant.
Tartaric acid was first isolated from potassium tartrate, known to the ancients as tartar, circa 800 CE by the alchemist Jabir ibn Hayyan, who was also responsible for numerous other basic chemical processes still in use today. The modern process was developed in 1769 by the Swedish chemist Carl Wilhelm Scheele. The chirality of tartaric acid was discovered in 1832 by Jean Baptiste Biot, who observed its ability to rotate polarized light. Louis Pasteur continued this research in 1847 by investigating the shapes of tartaric acid crystals, which he found to be asymmetric. Pasteur was the first to produce a pure sample of levotartaric acid.
Exactly, it is a dihydroxy derivative of dicarboxylic acid - 2,3-dihydroxysuccinic, or 2,3-dihydroxybutanedioic acid, with formula HO2C-CH(OH)-CH(OH)-CO2H (C4H6O6). Tartaric acid is chiral compound, meaning that it occurs in multiple stereoisomers. This property makes it a useful raw material in organic chemistry for the synthesis of other chiral molecules. The naturally occurring form of the acid is L-(+)-tartaric acid or dextrotartaric acid. The opposite form, levotartaric acid or D-(-)-tartaric acid, and the achiral form, mesotartaric acid, can be made artificially. Note, that the dextro and levo prefixes are not related to the D/L configuration (which is derived from the reference D- or L-glyceraldehyde), but to the orientation of the optical rotation, (+) = dextrorotatory, (-) = levorotatory. Sometimes, instead of capital letters, small italic d, l are used. They are abbreviations of dextro- and levo-, and nowadays should not be used. Levotartaric and dextrotartaric acid are enantiomers, mesotartaric acid is a diastereomer of both of them. Rarely occurring optically inactive form of tartaric acid, 1:1 mixture of the levo and dextro forms, DL-tartaric acid (which must not be confused with mesotartaric acid) was called racemic acid (from Latin racemus - "a bunch of grapes"). This word later changed its meaning, becoming a general term for 1:1 enantiomeric mixtures - racemates.
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Missing image | Missing image D-tartaric_acid.png Image:D-tartaric acid.png | Missing image DL-tartaric_acid.png Image:DL-tartaric acid.png |
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(natural) tartaric acid |
D-(-)-tartaric acid |
mesotartaric acid |
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(1:1) | ||
Important derivatives of tartaric acid include its salts, Cream of tartar (potassium hydrogen tartrate), Rochelle salt (potassium sodium tartrate, a mild laxative) and tartar emetic (antimony potassium tartrate).
Tartaric acid is a muscle toxin, which works by inhibiting the production of malic acid, and in high doses causes paralysis and death. The minimum recorded fatal dose for a human is about 12 grams. In spite of that, it is included in many foods, especially sour-tasting sweets.
When cream of tartar is added to water, a suspension results which serves to clean coins very well. The solution loosens surface dirt and grime on the coins. Then, the dirt can be wiped off quite easily.
SMILES string: [C@2H]([OH])([C@2H]([OH])[C](=[O])[O-])[C](=[O])[OH]
External link
- "History of Tartaric Acid" from Linan Euro-China Co., Ltd. (http://www.linanwindow.com/tartaric/history.htm)
Template:Commonsca:Àcid tàrtric de:Weinsäure es:Ácido tartárico nl:Wijnsteenzuur ja:酒石酸 pt:Ácido tartárico