D-Mannonic acid

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... 

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... 

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... 

The rates of hydrolysis of the lactones depend on the parent structure for instance, the 1,4-lactone of D-mannonic acid is more stable than that of D-gluconic acid, and the 1,4-lactones of 2-deoxyaldonic acids are more stable than the corresponding aldonolactones. The final attainment of equilibrium between free aldonic acids and their lactones is reached only after many days at room temperature it is, however, accelerated by the presence of strong acids and by heating. A detailed discussion of the formation and hydrolysis of aldonolactones is available in a review by Shafizadeh,59 and the conformations and stabilities of aldonolactones have been discussed by Lemieux.60 Detailed analyses of D-glucono-1,5-lactone and other lactones have been reported.61 13C NMR spectroscopy proved to be a convenient method for monitoring the equilibria.62... 

An unusual classification of hexonic acids described by Levene21 was based on the differences in optical rotation between the free acid and its sodium salt. For example, in the D-gluconic acid series the sodium salt has the more positive rotation whereas in the D-mannonic acid group the reverse is the case and the acid has the more positive rotation. In comparison with these results glucosaminic acid was found to have a rotation of —15° (and its sodium salt +1.3°) and therefore these derivatives were in conformity with the D-gluconic acid series. 

Fig. 2-28. Kiliani reaction. Addition of hydrogen cyanide to D-arabinose (1) yields cyanohydrins (2) and (3), which are hydrolyzed to D-gluconic acid (4) and D-mannonic acid (5). Because of asymmetric induction preferentially (4) is formed.

D-Gluconic acid, ammonium n-gluconate, sodium n-gluconate D-Arabonic acid, L-arabonic acid, potassium n-arabonate, citric acid D-Mannonic acid a-n-Galacturonic acid... 

D-Mannonic acid was prepared by Fischer and Hirschberger since the calcium, barium and cadmium salts were all amorphous, the crystalline phenylhydrazide was isolated. Hydrolysis with barium hydroxide followed by removal of the phenylhydrazine with ether and the barium with sulfuric acid gave the crystalline lactone. The phenylhydrazide could also be obtained (15% yield) by the oxidation of hydrolyzed ivory-nut meal. D,L-Mannose was converted by Fischer to D,L-mannonic acid and isolated as the phenylhydrazide. 

Chitose, a 2,5-anhydro-D-mannose obtained by Fischer by the action of nitrous acid on D-glucosamine, was oxidized with bromine to chitonic acid (2,5-anhydro-D-mannonic acid). 

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