Tartaric acid, ordinary

Hbtatartario aeid is produced by flising ordinary tartaric acid. 

Sometimes the subscript s or g is added to a d or l prefix to indicate whether the chirality of a compound is being related to that of serine, the traditional configurational standard for amino acids, or to that of gly-ceraldehyde. In the latter case the sugar convention (Chapter 4) is followed. In this convention the configurations of the chiral centers furthest from Cl are compared. Ordinary threonine is ls- or d -threonine. The configuration of dextrorotatory (+)-tartaric acid can be described as 2R, 3R, or as ds, or as l. ... 

The toxic action of white arsenic has been attributed to its inhibitory action on the oxidative processes,9 partly owing to the effect of the change of pH on the enzyme concerned. Small quantities of arsenious acid reduce the power of suitably prepared extracts of animal tissues to oxidise reduced phenolphthalein. The oxidation of tartaric acid at the ordinary temperature and at 37-5° C. is inhibited by arsenious acid, as also is the respiration and fermentation of yeast,10 but the latter... 

Ordinary tartaric acid, commonly present in grapes, is dextrorotatory and was long known as d- or dextro-tartaric acid. Its configuration has been established as HO H... 

The precipitation of aluminium hydroxide by solutions of sodium hydroxide and ammonia does not take place in the presence of tartaric acid, citric acid, sulphosalicylic acid, malic acid, sugars, and other organic hydroxy compounds, because of the formation of soluble complex salts. These organic substances must therefore be decomposed by gentle ignition or by evaporating with concentrated sulphuric or nitric acid before aluminium can be precipitated in the ordinary course of qualitative analysis. 

Ordinary (that is, dextrorotatory) tartaric acid (XX) corresponds to XXI and not to XXII, as is often stated erroneously in textbooks. Formula XXII applies to the enantiomorph of natural tartaric acid. Formulas XXI and XXIII are drawn in conformity with Fischer s first convention but formula XXII does not follow it. 

Dextro Tartaric Acid.—The ordinary tartaric acid as it occurs in grapes. 

In 1820 Sir John Herschel, in considering the question of the different optical rotation of crystalline substances, suggested that it might be connected with an unsymmetrical form of crystallization. Later, Pasteur in 1848 while studying the salts of tartaric acid recalled this suggestion of Herschel and also a statement by Mitscherlich to the effect that the crystalline form of ordinary tartaric acid which is dextro rotatory is identical with that of racemic acid which is inactive. At that time the tw o tartaric acids just mentioned were the only ones known. 

On studying the sodium-ammonium salt of ordinary tartaric acid (dextro tartaric acid), to see if there was any indication of unsymmetrical crystalline form with which to connect the optical activity, according to the suggestion of Herschel, Pasteur observed that the crystals possessed hemi-hedral facets. These gave to the crystals an unsymmetrical form. He then turned his attention to the second known tartaric acid, viz., racemic acid, which is optically inactive. His expectation was that in this acid no such unsymmetrical form would exist as it did not possess optical activity. But to his surprise he found, in the crystals of the sodium-ammonium salt, the same hemi-hedral facets that he had just found in the salts of the active acid. On closer examination. 

Thus from a study of the crystalline sodium-ammonium salt of racemic acid and of dextro tartaric acid Pasteur showed, conclusively, the relationship of these two acids to each other and also discovered the existence of a third isomer optically active but of opposite direction to the ordinary tartaric acid already known. Racemic acid, therefore, is optically inactive because it consists of equal molecules of the ordinary dextro tartaric acid and the newly discovered levo tartaric acid. Also racemic acid can be resolved into its optically isomeric components by mechanically separating the two forms of crystals of the sodium-ammonium salt. The two active forms of tartaric acid, when mixed in equal molecular amounts, yield the inactive or racemic acid. Later, Pasteur prepared the fourth variety of tartaric acid, viz., meso-tartaric acid, by heating the cinchonine salt of dextro tartaric acid. This new acid proved to be inactive like racemic acid, but, unlike it, was unable to be resolved into optically active components. Its relation to the other three forms of tartaric acid was unexplained by Pasteur. 

Dextro tartaric acid is the ordinary tartaric acid as it is found widely distributed in nature, in grapes, mountain ash berries, pineapples, potatoes and other plants. It crystallizes without water of crystallization in transparent, mono-clinic columns which are easily soluble in water or in alcohol. 100 parts of water at 15° dissolve 132 parts of the acid. It melts at i68°-i70°. In water solution it is dextro rotatory. The chief source of tartaric acid is the juice of the grape, where it is present as the free acid and as the acid potassium salt. In this source it is mostly the dextro variety that is found. It is obtained from the vinasse, or residue which settles out from the juice after it has been expressed. When grape juice ferments, in the formation of wine, the solubility of the acid potassium salt is lessened due to the presence of alcohol and it gradually separates and settles to the bottom iii the form of what is known as lees. These lees are dried or recrystallized once and the product is then known as crude tartar or argol. The crude tartar contains, in addition to the acid potassium tartrate, free tartaric... 

In 1951, it became possible to determine whether Rosanoff s guess was right. Ordinary X-ray crystallography cannot distinguish between a d and a l isomer, but by use of a special technique, Bijvoet was able to examine sodium rubidium tartrate and found that Rosanoff had made the correct choice. It was perhaps historically fitting that the first true absolute configuration should have been determined on a salt of tartaric acid, since Pasteur made his great discoveries on another salt of this acid. 

One of them, that which comes from crystals of the double salt hemi-hedral to the right, deviates to the right, and is identical with ordinary tartaric acid. The other deviates to the left, like the salt which furnishes it. The deviation of the plane of polarisation produced by these two adds is rigorously the same in absolute value. The right acid follows special laws in its deviation, which no other active substance had exhibited. The left add exhibits them, in the opposite sense, in the most faithful manner, leaving no suspidon of the slightest difference. 

To test for ordinary phosphorus, at least twenty-five match-heads are placed directly in a MitscheHich apparatus, with 50 c.c. of water and 10 c.c, of dilute sulphuric acid. The mixture is heated over a flame, without the introduction of steam ( p- 134) I potassium chlorate is present, the phosphorescence may not appear (c/. p. 135) but on the other hand, phosphorus sulphide is capable of producing a luminescence which, though different from that caused by phosphorus, may be mistaken for it. In the first case, either the substances soluble in water, including the potassium chlorate, must first be removed from the match-heads with cold water, or the test must be carried out with tartaric acid. To determine the presence of very small amounts of yellow phosphorus in red phosphorus the following test has been proposed by Kray —... 

Ketone syntheses. Reactivity discrimination between thiol esters and ordinary esters is the basis of an approach to chiral yalkylated butyrolactones from tartaric acid. Morpholine amides are simple substrates for Grignard reaction to provide ketones. ... 

Optical activity was first understood with respect to naturally occurring tartaric acid crystals by Pasteur in 1848. At this stage, the puzzle was that tartaric acid crystals were optically active, while the chemically identical racemic acid was not. The eventual results of the study revealed that racemic acid crystallised to give two morphologically different crystals, which were mirror images of each other, that is, they existed as a left-handed and right-handed pair. Each of these crystal types was identical to tartaric acid in every way except that crystals of one hand would rotate the plane of polarised light one way, just as ordinary tartaric acid,... 

These two diastereoisomers posses different properties, say, different solubilities, so that the two can be separated by one of the ordinary methods, say, by fractional crystallisation. After separation, the optically active reagent is removed from the molecule (if the diastereoisomer is a salt, it is treated with acid or alkali and if it is an ester, hydrolysis is carried out) and pure forms of enantiomers are isolated. Resolution of dl-tartaric acid is the classical example of the application of this method. 

The internal aanngemont is known only in tbe cose of ordinary and inactive tartaric acids, which arc both represented by rite above Cannula. 

The ordinary tartaric acid crystallizes in large prisms very soluble in HiO and alcohol acid in taste and reaction. It fuses at 170° (338° P.) at 180° (356° P.) it loses HjO, and is gradually converted into an anhydrid at 200°-210° (393°-410° P.) it is decomposed with formation of pyruvic acid, C H 03,and p3rrotartaric acid, CeHtO, at higher temperatures COs, CO, HjO, hydrocarbons and charcoal are produced. If kept in fusion some time, two molecules unite, with loss of HjO, to form tartralic or ditartaric acid, CsHioOii. 

Racemic acid is of considerable historical interest as it was the first inactive substance to be resolved into optically active compounds. The remarkable discovery was made by Pasteur in 1848 in an investigation of the crystalline structure of the salts of racemic acid. It was found that two kinds of crystals, which differed slightly in the relative position of the faces they contained, were formed when a solution of the sodium ammonium salt of racemic acid was allowed to crystallize spontaneously. The relation in form which the two kinds of crystals bear to each other, is that of an object and its reflection in a mirror. Pasteur separated the two kinds of crystals and examined the solutions of each in polarized light. He found that one solution was dextro-rotatory and the other was levo-rotatory. From the two salts two acids were isolated one was ordinary d-tartaric acid, the other a new acid which was levo-rotatory. When equal weights of the two acids were mixed and recrystallized, inactive racemic acid was obtained. 

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