Tartaric acid, stereoisomers projections

The separation of a racemic mixture into its enantiomeric components is termed resolution The first resolution that of tartaric acid was carried out by Louis Pasteur m 1848 Tartaric acid IS a byproduct of wine making and is almost always found as its dextrorotatory 2R 3R stereoisomer shown here m a perspective drawing and m a Fischer projection... 

We can draw these three stereoisomers as Fischer projections, reversing the configurations at both centres to get the enantiomeric stereoisomers, whilst the Fischer projection for the third isomer, the meso compound, is characterized immediately by a plane of symmetry. For (-l-)-tartaric acid, the configuration is 2R, >R), and for (—)-tartaric acid it is (2S,3S). For both chiral centres, the group of lowest priority is hydrogen, which is on a horizontal line. In fact, this is the case in almost all Fischer projections, since, by convention, the vertical... 

Fischer projections are especially useful in the case of compounds with more than one chirality center. For example, it is easy to see the plane of symmetry in meso-tartaric acid. As was the case with regular structures, interchanging any two groups in a Fischer projection results in inversion of configuration at the chirality center. Thus, interchanging the H and OH on the lower chirality center of weso-tartaric acid inverts the configuration at that chirality center, resulting in the (27 ,3R)-stereoisomer, (-i-)-tartaric acid. It is also easy to see that this stereoisomer does not have a plane of symmetry. 

More elaborate molecules can also have a plane of symmetry. For example, there are only three stereoisomers of tartaric acid (2,3-dihydroxybutanedioic acid). Two of these are chiral but the third is achiral. In the achiral stereoisomer, the substituents are located with respect to each other in such a way as to generate a plane of symmetry. Compounds that contain two or more stereogenic centers but have a plane of symmetry are called meso forms. Because they are achiral, they do not rotate plane polarized light. Note that the Fischer projection structure of meio-tartaric acid reveals the plane of symmetry. 

Fischer esterification. See Esterification Esters Fischer projection formulas, 271-272, 278, 280, 292, 595 a-amino acids, 1056, 1103 carbohydrates, 973-974, 1007 of meso stereoisomer, 280 tartaric acids, 286... 

Fischer projections of the stereoisomer of tartaric acid Physical Properties of the Stereoisomers of Tartaric Acid... 

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