Mannitol from mannose

Tetritols, pentitols and hexitols are largely known according to the names of the sugar molecules from which they derive. Thus the pentitol, xylitol (see Fig. 5), derives from xylose and mannitol from mannose sorbitol derives from glucose. Such reduced sugars may be used as sweetening... 

This is now confirmed by the formazan reaction. From ozone-oxidized D-mannitol, n-mannose can be isolated in the form of its iV,iV -diphenyl-formazan. Applying this reaction to ozone-oxidized polysaccharides (for example, cellulose or starch), their bright-red formazans are obtained. ... 

A multi-step process has also been developed for the preparation of mannitol from D-glucose [31,32]. D-Glucose is first epimerized to D-mannose by molybdate and D-glucose remaining in the mixture is then treated with glucose isomerase to establish equilibrium with D-fructose. Finally, the glucose-mannose-fructose mixture is hydrogenated to yield 40 % mannitol. 

D-mannitol is widely used as sweetening agent and finds also different application in the food industry and related areas [1]. D-mannitol can be directly prepared from mannose or by stereoselective hydrogenation of D-fructose. However, the hydrogenation of D-fructose in aqueous solution over different heterogeneous catalysts leads to the formation of two isomers, i.e. D-mannitol and D-sorbitol, near to a ratio of one to one [1]. 

If the aldehyde or ketone functions of aldoses or ketoses respectively are reduced to alcohols the molecules produced have open-chain structures and are called sugar alcohols. They are denoted by the end -itol . Hence that derived from ribose is ribitol, that from mannose is mannitol and so on. They are chiefly encountered in bacterial polymers. 

D-mannose. A paper on the synthesis of swainsonine from mannose mentioned in Chapter 24 includes a practical synthesis of 1,4-di-deoxy-1,4-imino-D-mannitol. 

Reduction of the carbonyl group produces the corresponding polyalcohol for example, mannitol is obtained from mannose. 

D,L-Mannitol has been obtained by sodium amalgam reduction of D,L-mannose. The identical hexitol is formed from the formaldehyde polymer, acrose, by conversion through its osazone and osone to D,L-fmctose (a-acrose) followed by reduction (83). 

The molecular weight (94,000) was smaller than that of other microbial P-mannosidases such as Aspergillus o/jCTe( 120,000-135,000) and Tremella fuciformis (160,000-200,000). The final product from the oligosaccharides with the enzyme was mainly D-mannose and the enzymatic activity was not inhibited by D-mannose or mannose-derivatives such as D-mannosamine, D-mannonic acid and D-mannitol. 

On the other hand, borohydride reduction of the ketose o-fructose will give a mixture of o-glucitol and its epimer, D-mannitol. A better approach to D-mannitol would be reduction of the aldose D-mannose. o-Glucitol (sorbitol) is found naturally in the ripe berries of the mountain ash (Sorbus aucuparia), but is prepared semi-synthetically from glucose. It is half as sweet as sucrose, is not absorbed orally, and is not readily metabolized in the body. It finds particular use as a sweetener for diabetic products. o-Mannitol also occurs naturally in manna, the exudate of the manna ash Fraxinus ornus. This material has similar characteristics to sorbitol, but is used principally as a diuretic. It is injected intravenously, is eliminated rapidly into the urine, and removes fluid by an osmotic effect. 

J. C. Irvine and Bina M. Patterson, J. Chem. Soc., 106, 916 (1914). The methylated n-mannose was prepared from or-methyl n-mannoside, which the authors thought to be furanoid. The ether was reported as 2,3,5,0-tetramethyl-n-mannitol, but, since the starting n-mannoside is now known to have been pyranoid, the ester must be 2,3,4,6-tetramethyI-n-mannitol. 

L-Mannitol does not occur naturally but is obtained by the reduction of L-mannose or L-mannonic acid lactone (80). It can be synthesized from the relatively abundant L-arabinose through the L-mannose and L-glucose cyanohydrins, conversion to the phenylhydrazines which are separated, liberation of L-mannose, and reduction with sodium borohydride (81). Another synthesis is from L-inositol (obtained from its monomethyl ether, quebrachitol) through the diacetonate, periodate oxidation to the blocked dialdehyde, reduction, and removal of the acetone blocking groups (82). 

The same compounds isolated by Brigl and coworkers,9 who started from 2,3,4,5,6,7-hexa-O-benzoyl-D-gZt/cero-D-gaZacto-heptononitriIe, were obtained from the ammonolysis of 1,2,3,4,6-penta-O-benzoyl-a-D-mannose,19 namely, a mixture of l,l-bis(benzamido)-l-deoxy-D-mannitol (12) and N-benzoyl-D-mannopyranosylamine (13). Likewise, 1,2,3,4-tetra-O-benzoyl-L-rhamnopyranose,10 having the same steric relationship at the asymmetric carbon atoms as the perbenzoate of D-mannose, also afforded an N-benzoyl-L-rhamnopyranosylamine directly. 

Formerly the raw material for the production of nitromannitol, i.e. mannitol, was prepared from the juice of berries, in particular from Traxinus ornus (manna). At present it is produced by reducing D-mannose or D-fructose in the latter case D-sorbitol is also formed. 

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