Fischer projections tartaric acids

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... 

The Newman representation 25a or 26a of meso-tartaric acid does not have a mirror plane. Why is it different from the Fischer projections in this respect The reason is that the projection formulas represent a particular eclipsed conformation 27 of tartaric acid that does have a mirror plane ... 

Figure 2 Fischer projections of (a) (2/t,3/Q-tartaric add, (b) (2S,3S)-tartaric add and (c) (2/ ,35)-tartaric acid (meso-...

Rotate around the C2-C3 bond to give an eclipsed sawhorse projection. This can be converted into a Fischer projection. Remember that vertical lines project behind the plane of the page and horizontal lines project out of the page. There are several correct Fischer projections in this case. The plane of symmetry, which is easily seen in the projection shown above, shows that this is meso-tartaric acid. 

Use the Fischer projection of meso-tartaric acid and carry out even and odd exchanges of the groups follow these exchanges with a model. Does an odd exchange lead to an enantiomer, a diastereomer, or to a system identical to the meso form (15a) Does an even exchange lead to an enantiomer, a diastereomer, or to a system identical to the meso form (15b) ... 

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. 

An efficient and large scale resolution of methylphenidate (ritalin hydrochloride)using dibenzoyl-tartaric acid has been described (61). Ritalin is marketed for the treatment of children with attention deficient disorder (ADHD). Methylphenidate has two chiral centers and originally was marketed as a mixture of two racemates, 20% OL-threo (29, 30) and 80%DL-erythro (31, 32) (see Fig. 18.12 for the structures of all four isomers). As introduced previously, the erythro-isomer is defined as the case when the main chain of a molecule (drawn vertically in a Fischer projection)has identical or similar substituents at two adjacent non-identical chiral centers on the same side of the chain, whereas the threo isomer has... 

Fischer then shows that when the arrangements for the enantio-morphous forms of saccharic acid that are specified by his use in his first article of Van t Hoff s -f and — signs (number 5 = 11 and 9 = 15 of Table I) are given to models, and these are projected as in the case of the tartaric acids, the formulas XII and XIII result. The present author has added the diagrams XI (= XII) and XIV (= XIII) in which the dotted straight line indicates those edges of the tetrahedra that lie in the plane of the paper this line is dotted to indicate that these edges are not... 

PROBLEM 7.19 There are two other stereoisomeric tartaric acids. Write their Fischer projections, and specify the configuration at their stereogenic centers. 

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... 

Write a Fischer projection formula for a tartaric acid isomer that is not chiral. 

Convert the following sawhorse formula for one isomer of tartaric acid to a Fischer projection formula. Which isomer of tartaric acid is it ... 

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

Fischer projection formulas are often used to depict compounds such as glyceraldehyde, lactic acid, and tartaric acid. Draw Fischer projections for both enantiomers of (a) glyceraldehyde, (b) tartaric acid, and (c) lactic acid, and specify the (R) or (S) configuration at each chirality center. [Note that in Fischer projection formulas the terminal carbon that is most highly oxidized is placed at the top of the formula (an aldehyde or carboxylic acid group in the specific examples here).]... 

Acyclic Alditols. - A simple method has been described for transforming Fischer projections into zig-zag forms. Dipole-dipole interactions of D-sorbitol in water and methanol solution have been studied, and evidence for solute-solvent interactions presented. The preparation of 1,4-di-O-benzyl-L-threitol from L-tartaric acid in 4 steps has been reported. A study of optical rotations of (S)-propane-l,2-diol, D-t/ reo-butane-2,3-diol as well as some alditols and some deoxyalditols in aqueous and non-aqueous solution has been reported D-glucitol, for example, is dextrorotaiy in DMSO or HMPT but levorotary in water or pyridine. The dependence of rotation on the solvent is considered in detail. The mass spectra of some per-O-benzoylalditols have been described. ... 

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