Tartaric acid - Definition and Overview

Tartaric acid is white crystalline organic acid. It occurs naturally as algol (an impure form of potassium hydrogen tartrate) which is a by-product of the fungus responsible for the fermentation of wine, giving wine some of its sharp taste, and is also found in tamarinds. It is added to other foods to give an acid taste, and as an antioxidant.

Tartaric acid was first isolated from potassium tartrate, known to the ancients as tartar, 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, insead 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, it became a general term for 1:1 enantiomeric mixtures - racemates. ­­

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]

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