Saccharinic acids structure

The saccharinic acids formed from hexoses have been especially examined because of the relationships of the a and /8 isomers (C-2 epi-mers). Structures of saccharinic acids derived from D-glucose are glu-cometasaccharinic acid (51), glucoisosaccharinic acid (52), and glucosaccharinic acid (53). The a- and /3- isomers of metasaccharinic acid can reversibly isomerize when exposed to base because of the labile proton at C-2. 

The (branched) amylopectin is generally considered more alkali-stable than amylose. Amylopectin produced a very small proportion of glucoiso-saccharinic acid after exposure to M KOH at 25° for nearly 2 months."" However, glycogen, which has a similar structure, but more a-D-(1 6) bonding, undergoes the peeling process where a-o-(1 4) bonds are pre-... 

Three structurally isomeric forms have been established for the six-carbon saccharinic acids. In the order of their discovery, these are the sac-charinic or 2-C -methylpentonic acids, the isosaccharinic or 3-deoxy-2-C -(hydroxymethyl)-pentonic acids, and the metasaccharinic or 3-deoxy-hexonic acids. Although none of these six-carbon, deoxyaldonic acids has been crystallized, six are known in the form of crystalline lactones (saccharins). All the possible metasaccharinic acids of less than six-carbon content have been obtained, in the form of crystalline derivatives, by the sugar-alkali reaction. Only one example of a branched-chain deoxyaldonic acid (the racemic, five-carbon isosaccharinic acid) of other than six-carbon content has been so obtained. The formation of saccharinic acids containing more than six carbon atoms remains to be explored. 

The best evidence for the formation of 8 -D-isosaccharinic acid in the sugar-alkali reaction is the recent observation" that treatment of lactose, maltose, or 4-0-methyl-D-glucose with lime-water at room temperature provides initially a mixture of saccharinic acids consisting almost exclusively of a -D-isosaccharinic acid plus an acid with the properties of Nef s /3 -D-isosaccharinic acid [brucine salt, m. p. 185 to 210 (dec.), [a]n - 20 to —22° lactone, [ajp -)-6 to - -8.5°]. An experimental proof that this substance possesses the isosaccharinic acid structure would provide the necessary evidence that it is, indeed, the epimer of a -D-isosaccharinic acid. 

The final phase of the Nef mechanism, which involves a benzilic acid type of rearrangement of a-dicarbonyl intermediates to the saccharinic acids, is at present accepted as a feature of saccharinic acid formation. Nef s concept of the conversion of reducing sugars to the a-dicarbonyl structures required revision, however, when it became evident that the formation, in this step, of the proposed methylenic intermediates is highly improbable. A departure from the methylenic intermediates was suggested in 1926 by Evans and Benoy, who proposed that the a-dicarbonyl intermediates of the Nef mechanism might arise by successive dehydration and rehydration from the enediols. It is now recognized, however, that forma-... 

An experimental demonstration that the Nef mechanism for the initial conversion of a sugar by alkali to the a-dicarbonyl structure is not acceptable was provided by a study of the action of alkali on 2 hydroxy-3-meth-oxy-3-phenylpropiophenone. Nicolet observed that the products in this case are 2,3-diphenyllactic acid and methanol. This conversion, which is completely analogous to the formation of a saccharinic acid from a reducing sugar, demonstrated clearly that carbon-oxygen cleavage occurs at the /3-carbon atom, rather than at the a-carbon atom, with respect to the carbonyl group. 

The definition is not, perhaps, entirely satisfactory. It is arbitrary and formal. It does not include those acids of formula C H2 0 which contain a quaternary carbon atom, because the hydroxy-aldehyde of like general formula required by the definition is structurally impossible. In other words, such acids could not be formed by the imaginary reaction which is the basis for the defintion and they would, therefore, not be called saccharinic acids. On the other hand, the definition does have the advantage of perfect clarity. Furthermore, it establishes a connection between the saccharinic acids and the aldoses. Finally, it escapes the drawback of a functional definition, because it depends, not on an actual, but on a theoretically possible, number of isomers. The term saccharinic acid will be used in this article to denote only those compounds encompassed by the Glattfeld-Sherman definition. 

Effect of Structure of Glycosyl Units on Saccharinic Acids Produced... 305... 

Gum arabic is a mixture of Ca, Mg and K salts of Arabic saccharinic acid which consists of 1-D-hexanic acid, 3-D-galactose, 2-L-arabic saccharide and 1-L-rhamnose. The saccha-rosan is contained in seeds, bud stems, roots, leaves and skins of many plants. In general, all the gums, including starches and cellulose, are natural polymers of the saccharide units although their structures are quite different from one another. Starch has a simpler struc-... 

The branched-chain structure of saccharinic acid is demonstrated by the reduction of the acid by hydrogen iodide (and phosphorus) to 2-methyl-pentanoic acid ... 

Branched-chain aldonic acids have received attention (see also saccharinic acids). The synthesis of the L-ldonate and D-galactonate derivatives (6) and (7) as shown in Schemes 2 and 2b served to confirm the structures of the branched-chain 2,3-0-... 

Saccharin was discovered at Johns Hopkins Uni versity in 1879 in the course of research on coal tar derivatives and is the oldest artificial sweetener In spite of Its name which comes from the Latin word for sugar saccharin bears no structural relationship to any sugar Nor is saccharin itself very soluble in wa ter The proton bonded to nitrogen however is fairly acidic and saccharin is normally marketed as its water soluble sodium or calcium salt Its earliest applications were not in weight control but as a... 

Relatively high molecular weight is a feature of the chemotype exemplified by 4-11 and this can require creative formulation techniques. Pharmacokinetic properties of a lead candidate (structure unknown) from the same series that provided 10 were inadequate to provide sufficient exposures at high doses to support preclinical safety studies. However, cocrystal formulations with saccharin or gentisic acid improved water solubility by 50-fold and increased oral exposures up to 10-fold relative to traditional formulations at 20mg/kg [64]. 

A first requirement for a substance to produce a taste is that it be water soluble. The relationship between the chemical structure of a compound and its taste is more easily established than that between structure and smell. In general, all acid substances are sour. Sodium chloride and other salts are salty, but as constituent atoms get bigger, a bitter taste develops. Potassium bromide is both salty and bitter, and potassium iodide is predominantly bitter. Sweetness is a property of sugars and related compounds but also of lead acetate, beryllium salts, and many other substances such as the artificial sweeteners saccharin and cyclamate. Bitterness is exhibited by alkaloids such as quinine, picric acid, and heavy metal salts. 

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