Dulcitol, Sorbitol

Synthesis from Poly-alcohols.—We come, now, to that group of mono-saccharoses, the hexose mono-saccharoses, which contains the most important simple sugars which are known, viz., glucose and fructose. The hexoses may be prepared, synthetically, by oxidizing the hexa-hydroxy alcohols, e.g. mannitol, dulcitol, sorbitol, etc. (p. 219). 

Fig. 2. Structures of hexitols (a) allitol, (b) sorbitol (D-glucitol), (c) D-maimitol, (d) dulcitol, (e) L-iditol, and (f) D-altritol.

Isomerization of sorbitol, D-mannitol, L-iditol, and dulcitol occurs in aqueous solution in the presence of hydrogen under pressure and a nickel—kieselguhr catalyst at 130—190°C (160). In the case of the first three, a quasiequiUbrium composition is obtained regardless of starting material. Equilibrium concentrations are 41.4% sorbitol, 31.5% D-mannitol, 26.5% L-iditol, and 0.6% dulcitol. In the presence of the same catalyst, the isohexides estabUsh an equihbrium at 220—240°C and 15.2 MPa (150 atm) of hydrogen pressure, having the composition 57% isoidide, 36% isosorbide, and 7% isomannide (161). 

Boron zirconimn chelates from ammonium hydroxide water-soluble amines sodium or potassimn zirconium and organic acid salts such as lactates, citrates, tartrates, glycolates, malates, gluconates, glycerates, and mandelates with polyols such as glycerol, erythritol, arabitol, xylitol, sorbitol, dulcitol, mannitol, inositol, monosaccharides, and disaccharides [463,464,1592,1593]... 

Figure 17-17. Arabitol, dulcitol, erythritol, glycerol, inositol, mannitol, and sorbitol.

Crystalline 1,4-anhydro-D-sorbitol is of much more recent origin than 1,4-anhydro-D-mannitol, inasmuch as its preparation was first recorded in 1946.10 It was obtained by the restricted dehydration of D-sorbitol and has been given the trivial name arlitan. Two groups of workers simultaneously effected proof of its constitution. Hockett and coworkers11 treated the anhydride with lead tetraacetate and since its rate of oxidation coincided with that of ethyl D-galactofuranoside and since one molecular proportion of formaldehyde was formed, the authors concluded that the ring must involve Cl and C4 of a hexitol chain. Assuming that no other carbon atoms are involved, sorbitan is either 1,4-anhydro-D-sorbitol or 1,4-anhydro-D-dulcitol (Walden inversion at C4 of the sorbitol molecule). They therefore synthesized 3,6-anhydro-D-dulcitol (enantio-morphous with 1,4-anhydro-L-dulcitol) but found it to be different from arlitan. 

The stereochemistry of the hexitols affects the manner of ring fusion, as is seen in Figs. 3 and 4. In mannitol, sorbitol (gulitol) and iditol, the l,4 3,6-dianhydro rings are m-oriented, whereas in the dulcitol, allitol and altritol (talitol) series the 1,4 3,6-rings are trans-oriented. This makes the ring system in this latter series almost planar although in the case of dianhydrodulcitol and allitol there is considerable strain in the molecules. 

Sorbitol, D-mannitol, L-iditol and dulcitol are found in plant sources. Synthetic preparation is simpler than isolation. The six other isomers... 

Dulcitol is no longer obtained in practice from Madagascar manna or other natural sources, but is produced by the catalytic hydrogenation of D-galactose, or, along with sorbitol, of hydrolyzed lactose because of its lower solubility in water it is readily separated from the sorbitol. 

D-Mannitol, sorbitol and dulcitol are oxidized at the same rate by lead tetraacetate. 

The subtle differences between sugar molecules which cause such dramatic effects (Le. Dulcitol verses sorbitol) are possibly caused by adverse interactions either with water or the amino acids of the protein. It is possible that under certain conditions the position of hydroxyl groups causes strong binding of water and leads to confirma-tional distortion of the protein rather than stabilization. Monsan and Combes (13) have suggested that this is due to excessive binding to the stabilizer thus disrupting the protein surface/water interactions. As yet we have no evidence to further elucidate this theory. 

They found that these rules complied with the structures that were then known for the methylene acetals of sorbitol, mannitol, dulcitol, iditol, 6-desoxy-sorbitol, xylitol and ribitol. From the rules they predicted structures for methylene acetals of allitol and talitol, and several of these predicted acetals have been discovered in later researches. Among the... 

Bacteriological culture media, dulcitol, mannitol and sorbitol in, I, 192 Bacterium amylobacter, in fermentation of wood sugars, IV, 184 Bacterium dysenteries, antigens, II, 199 Bacterium xylinoides, cellulose formation by, II, 206... 

This isomer of sorbitol and mannitol is less soluble and less sweet than the other two compounds. Also it is less available for the multiplicity of uses which mannitol and sorbitol have enjoyed. Dulcitol was first designated as the mannite of Madagascar manna and was shown by Laurent in 1850 to be an isomer of mannitol. It is a meso form. In 1871 Bouchardat synthesized the compound by reducing D-galactose with sodium amalgam. Until ten years ago, the only biological studies available on dulcitol were of a bacteriological nature. At that time the authors studied the fate of dulcitol and dulcitan in the animal body. 

It was observed that dulcitol was a precursor of glycogen in the liver of the white rat, although its capacity to produce glycogen upon repetitious feeding was less marked than that of mannitol and far less marked than that of sorbitol. Dulcitol neither elevated the respiratory... 

The solution and solid state structures of the following sugar alcohols are discussed in separate sections erythritol 1, D-threitol 2, xylitol 3, D-arabitol 4, ribitol 5, D-mannitol 6, dulcitol 7, and D-sorbitol 8. 

Other sugar alcohols, such as n-sorbitol and n-dulcitol, give an aldose phenylhydra-zone which is hard to isolate and convert to the formazan. Therefore, the aldose (n-glucose from n-sorbitol) was transformed into glucosazone, which was identified with the aid of the formazan reaction as n-glucosazone formazan (4). 

Creighton process. Electrochemical reduction of sugars, e.g., reduction of glucose, xylose, and galactose to sorbitol, xylitol, and dulcitol. 

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