Mannonic acids

L-Mannonic acid y-lactone was purchased from Sigma Chemical Company, St. Louis, MO. 

Methyl 3,6-anhydro-a-D-manno-pyranoside 3,6-Anhydro-n-mannonic acid 131 + 97.1 HjO 14, 42... 

In the light of our present knowledge of the mechanism of these deamination reactions, it can be understood why deamination of either 2-amino-2-deoxy-D-mannonic acid, or the corresponding lactone, gives 2,5-anhydro-D-mannonic acid.39-42... 

Fig. 4.—The discovery of asymmetric induction. The yield of the /-mannonic acid, under the conditions then used, was about three times greater than that of the gluco isomer (see Table I).

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. 

Levene found that the nitrous acid deamination of 2-amino-2-deoxy-D-mannonolactone (14) gives 2,5-anhydro-D-mannonic acid (16), a result identical with that obtained by similar deamination of the corresponding acid (15). On the other hand, the same reaction performed... 

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). 

Natural D-mannose is the aldehyde of natural D-mannitol, and is transformed by the action of bromine water into D-mannonic acid, which was isolated as its phenylhydrazide. The acid was regenerated from the phenyl-hydrazide and isolated as its crystalline lactone. Kiliani hod obtained the enantiomorph of this lactone on applying the cyanohydrin reaction to natural L-arabinose. A mixture of both lactones formed a racemate. Then, by taking recourse to his newly discovered reduction of the lactones to the aldoses, a reaction which Fischer designated the most significant in the... 

Initially, only the nitrile of L-mannonic acid was found on addition of hydrocyanic acid to L-arabinose this acid retained the original arabinose in the asymmetry centers 3, 4, and 5. The new center of asymmetry created in this way at C-2 was first considered by Fischer to be racemic. This would have meant that the L-mannonic acid should be a partial racemate however, attempts to separate it into two stereoisomers failed. The idea of a partial racemate led to the question as to whether L-mannonic acid and D-gluconic acid (which are enantiomorphous on carbon atoms 3, 4, and 5) could form such a partial racemate (which would still be optically active). Such a compound could not be isolated, but negative results have only limited values as proof. ... 

Watters, Hockett and Hudson1 have prepared a non-crystalline monomethylmannose which forms an osazone with the same properties as those of 6-methyl-n-glucosazone. The synthesis was achieved by methylation of methyl 2,3,4-triacetyl-a-D-mannopyranoside, followed by hydrolysis. Schmidt and Heiss,13 studying the epimerization of 6-methyl-D-gluconic acid, have claimed to have isolated the phenyl-hydrazide of 6-methyl-n-mannonic acid. 

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