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Tartaric acid enantiomers

The answer is that Pasteur started with a 50 50 mixture of the two chiral tartaric acid enantiomers. Such a mixture is called a racemic (ray-see-mi c) mixture, or racemate, and is denoted either by the symbol ( ) or the prefix cl,I to indicate an equal mixture of dextrorotatory and levorotatory forms. Racemic mixtures show no optical rotation because the (+) rotation from one enantiomer exactly cancels the (-) rotation from the other. Through luck, Pasteur was able to separate, or resolve, racemic tartaric acid into its (-f) and (-) enantiomers. Unfortunately, the fractional crystallization technique he used doesn t work for most racemic mixtures, so other methods are needed. [Pg.307]

Figure 14.8 Adsorption models of the bisuccinate and bitartrate phases on Cu(1 1 0). (a) Structural models for the two coexisting chiral domains for bisuccinate on Cu(1 1 0). The (2 2, -9 0) and (9 0, -2 2) unit cells of the overall structure are shown as are the (2 2, -2 0) and (2 0, -2 2) unit cells representing the packing within each chain, (b) Structural models of the bitartrate phases of the two tartaric acid enantiomers on Cu(1 1 0) (S,S)-bitartrate (9 0, -1 2) and (/ ,R)-bitartrate (1 2, -9 0). The (3 1, -2 1) unit cell is also shown for the (/ ,/ )-bitartrate phase showing the packing within the chain [203],... Figure 14.8 Adsorption models of the bisuccinate and bitartrate phases on Cu(1 1 0). (a) Structural models for the two coexisting chiral domains for bisuccinate on Cu(1 1 0). The (2 2, -9 0) and (9 0, -2 2) unit cells of the overall structure are shown as are the (2 2, -2 0) and (2 0, -2 2) unit cells representing the packing within each chain, (b) Structural models of the bitartrate phases of the two tartaric acid enantiomers on Cu(1 1 0) (S,S)-bitartrate (9 0, -1 2) and (/ ,R)-bitartrate (1 2, -9 0). The (3 1, -2 1) unit cell is also shown for the (/ ,/ )-bitartrate phase showing the packing within the chain [203],...
The crystallization procedure employed by Pasteur for his classical resolution of ( )-tartaric acid (Section 5-1C) has been successful only in a very few cases. This procedure depends on the formation of individual crystals of each enantiomer. Thus if the crystallization of sodium ammonium tartrate is carried out below 27°, the usual racemate salt does not form a mixture of crystals of the (+) and (—) salts forms instead. The two different kinds of crystals, which are related as an object to its mirror image, can be separated manually with the aid of a microscope and subsequently may be converted to the tartaric acid enantiomers by strong acid. A variation on this method of resolution is the seeding of a saturated solution of a racemic mixture with crystals of one pure enantiomer in the hope of causing crystallization of just that one enantiomer, thereby leaving the other in solution. Unfortunately, very few practical resolutions have been achieved in this way. [Pg.870]

Louis Pasteur (1822-1895) w/as born at Dole in the Jura region of France, the son ot leather tanners. After receiving his doc-toiate froiii the Ecole Nurmale Superieure at age 25, his landmark discovery of tartaric acid enantiomers was made only 1 year later. Pasteur is best known for his studies in bacteriology and for his discovery of vaccines for anthrax and rabies. [Pg.297]

The answer is that Pasteur started with a 50 50 mixture of the two chiral tartaric acid enantiomers. Such a mixture is called a racemic (ray-see-mic) mixture, or racemate, and is denoted either by the symbol ( ) or by... [Pg.325]

TABLE 5.1 PHYSICAL PROPERTIES OF 2-BUTANOL AND TARTARIC ACID ENANTIOMERS ... [Pg.207]

Tartaric acid is an inexpensive and readily available chiral starting material for the synthesis of chiral molecules. In a well-known prostaglandin synthesis, the (S,S)-tartaric acid enantiomer was used to prepare the chiral diol in several steps. The chiral diol was isolated as a synthetic intermediate, and the following reagents are used. Draw the structures of synthetic intermediates A and B. [Pg.482]

When cinkotoxine (a chiral base, similar to quinotoxine, without CH3O- substituent) was used, the other tartaric acid enantiomer ((S,S)-TA) crystallized in the diastereoisomeric salt. [Pg.8]

It may happen frequently, that only one enantiomer of the resolving agent is available, or one of the two enantiomers is significantly cheaper. For this reason mainly (R,R)-tartaric acid is used industrially among of tartaric acid enantiomers and their derivatives. It is the case, for example, at the resolution of a racemic intermediate (AN) of a-methyl-DOPA. The resolution of racemic AN is performed in the aqueous solution of its hydrochloric acid salt... [Pg.21]

Figure 3.10 XRPD patterns for differently prepared samples of the tartaric acid enantiomers. The figure illustrates the influence and the importance of an adequate sample preparation procedure for subsequent DSC measurements, (a) L-tartaric... Figure 3.10 XRPD patterns for differently prepared samples of the tartaric acid enantiomers. The figure illustrates the influence and the importance of an adequate sample preparation procedure for subsequent DSC measurements, (a) L-tartaric...
Physical Properties of 2-Butanol and Tartaric Acid Enantiomers... [Pg.201]

Mixtures of the enantiomers of a compound have different properties than pure samples of each, however. The data in Table 5.1 illustrate this for tartaric acid. The natural isomer, (+)-tartaric acid, has a melting point of 168-170°C, as does its unnatural enantiomer, (—)-tartaric acid. An equal mixture tartaric acid enantiomers, (+/—)-tartaric acid, has a melting point of 210-212°C, however. [Pg.201]


See other pages where Tartaric acid enantiomers is mentioned: [Pg.330]    [Pg.327]    [Pg.307]    [Pg.140]    [Pg.58]    [Pg.207]    [Pg.49]   
See also in sourсe #XX -- [ Pg.130 , Pg.130 , Pg.140 ]




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