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( Tartaric acid)
171-174 °C (L-tartaric)
206 °C (DL, racemic)
146-148 °C (meso) [2] Tartaric acid was first isolated from potassium tartrate, known to the ancients as tartar, c. 800 by the Persian alchemist Jabir ibn Hayyan,[citation needed] 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. Naturally occurring tartaric acid is chiral, meaning that it has molecules that are non-superimposable on their mirror-images. It is a useful raw material in organic chemistry for the synthesis of other chiral molecules. The naturally occurring form of the acid is L-(+)-tartaric&_160;acid or dextrotartaric&_160;acid. The mirror-image (enantiomeric) form, levotartaric&_160;acid or D-(-)-tartaric&_160;acid, and the achiral form, mesotartaric&_160;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. A rarely occurring optically inactive form of tartaric acid, DL-tartaric acid is a 11 mixture of the levo and dextro forms. It is distinct from mesotartaric acid and was called racemic&_160;acid (from Latin racemus - "a bunch of grapes"). The word racemic later changed its meaning, becoming a general term for 11 enantiomeric mixtures - racemates. Tartaric acid is used to prevent Copper(II) ions from reacting with the hydroxide ions present in the preparation of copper(I) oxide. Copper(I) oxide is a reddish brown solid, and is produced by the reduction of a Cu(II) salt with an aldehyde, in an alkaline solution.
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