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TARTARIC ACID (dihydroxy-succinic aci...

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Originally appearing in Volume V26, Page 436 of the 1911 Encyclopedia Britannica.
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TARTARIC See also:

ACID (dihydroxy-succinic acid), C4H6O6 , or HO2C•CH(OH)•CH(OH)•See also:CO2H. Four acids of this See also:composition are known, namely dextro- and laevo-tartaric acids, racemic acid and mesotartaric acid, the two last being optically inactive (see STEREO-See also:ISOMERISM). Their constitution follows from their formation from dibromosuccinic acid and from their See also:synthesis from glyoxal cyanhydrin, these two methods producing the inactive racemic See also:form which may then be split into the active components. Dextro-tartaric acid occurs in the See also:free See also:state or as the See also:potassium or See also:calcium See also:salt in See also:grape juice and in various unripe fruits. During the alcoholic See also:fermentation of grape juice it is deposited in the form of an impure acid potassium tartrate which is known as See also:argol, and when purified as cream of See also:tartar. For the preparation of the acid the crude argol is boiled with hydrochloric acid and afterwards precipitated as calcium tartrate by boiling with See also:milk of See also:lime, the calcium salt being afterwards decomposed by sulphuric acid. It may also be obtained (together with racemic acid) by oxidizing milk See also:sugar, saccharic acid, &c., with nitric acid, and by the reduction of oxalic ester with See also:sodium See also:amalgam (H. Debus, See also:Ann., 1873, 166, p. Io9). It crystallizes from See also:water in large prisms which melt at 168–170° C., and on further See also:heating gives an anhydride and finally chars, emitting a characteristic odour and forming pyroracemic and pyrotartaric acids. It behaves as a reducing See also:agent. Chromic acid and potassium permanganate oxidize it to formic and carbonic acids, whilst See also:hydrogen peroxide in the presence of ferrous salts gives dihydroxymaleic acid (H.

J. H. See also:

Fenton, Jour. Chem. See also:Soc., 1894, p. 899; 1895, pp. 48, 774; 1896, p. 546). Hydriodic acid and See also:phosphorus reduce it to malic acid and finally to succinic acid. Calcium chloride gives a See also:white precipitate of calcium tartrate in neutral solutions, the precipitate being soluble in See also:cold solutions of See also:caustic potash but re-precipitated on boiling. It prevents the precipitation of many metallic hydroxides by caustic alkalis. It carbonizes when heated with strong sulphuric acid, giving, among other See also:pro-ducts, See also:carbon monoxide and carbon dioxide.

A small crystal of oxalic acid added to concentrated sulphuric acid containing about I per cent. of See also:

resorcin gives a characteristic See also:violet red' coloration. Laevo-tartaric acid is identical in its chemical and in most of its See also:physical properties with the dextro-acid, differing chiefly in its See also:action on polarized See also:light, the See also:plane of polarization being rotated to the See also:left. By mixing equal quantities of the two forms in aqueous See also:solution See also:heat is evolved and racemic acid, (C,H6O6)2.2H2O, is obtained. This variety is also formed by the See also:hydrolysis of glyoxal cyanhydrin (F. Pollak, Monats., 1894, 15, p. 469); by heating a solution of desoxalic acid; by the oxidation of fumaric acid with potassium permanganate; by the action of See also:silver See also:oxide on dibromosuccinic acid, and by the oxidation of mannite, dulcite, See also:inulin, &c., with nitric acid. In the anhydrous state it melts at 205–206° C. Mesotartaric acid is formed when cinchonine tartrate is heated for some See also:time at 170° C. (L. See also:Pasteur, Ann., 1853, 88, p. 212); by heating tartaric or racemic acid for some time with water to 165° C.; by the oxidation of laevulose; and by the oxidation of phenol or maleic acid with an alkaline solution of potassium permanganate (O. Doebner, Ber., 1891, 24, p.

1755; A. See also:

Kekule and R. Anschutz, ibid., 1881, 14, p. 714). It crystallizes in prisms, and in the anhydrous state melts at 140° C. On pro-longed boiling with aqueous hydrochloric acid it yields racemic acid. The sodium ammonium salt is not capable of decomposition into its See also:optical See also:antipodes, as is sodium ammonium racemate. Tartaric acid as used in See also:medicine is derived from potassium acid tartrate. Its impurities are See also:lead, oxalic acid, lime and potassium tartrate. It is incompatible with potassium, calcium, See also:mercury and See also:vegetable astringents. Tartaric acid is rarely used alone, but is contained in pilula quininae sulphatis and in Seidlitz See also:powder (see SODIUM), and is a constituent of many proprietary granular effervescent preparations. If taken in overdose or in a concentrated form tartaric acid produces severe gastro-See also:enteritis.

In these cases lime-water, alkalis and See also:

magnesia should be used as antidotes, and See also:opium may be required.

End of Article: TARTARIC ACID (dihydroxy-succinic acid), C4H6O6

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