Mannonic acid 1,5-lactone

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). 

Racemic inositol has been reported as a constituent of fresh mistletoe berries where it occurs accompanied by meso-inositoP and also in small quantity in the stems of the liana Efiri. Historically, racemic inositol shares with Fischer s D,L-mannonic acid lactone the distinction of being the first racemate produced in the sugar series. - ... 

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

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... 

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... 

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. 

D-Mannonic acid y-lactone D-Arabonic acid y-lactone 39 0.01... 

These data indicate that the rate of hydrolysis of the lactones is also, to a considerable extent, affected by the stereoisomerism of the molecule. For instance, the lactones of n-mannonic acid are more stable than those of D-gluconic acid, from which they only differ in the steric position of the hydroxyl group at C2. A mixture of n-glucono-1,4-lactone and n-mannono-1,4-lactone can be fractionated by the absorption, on an anion-exchange... 

A solution of D-mannose (100 g) in water (21) was treated with calcium bromide (17.7 g) and calcium carbonate (55 g) and electrolysed, with stirring, in a suitable cylinder. Carbon electrodes, of 12 mm diameter, were placed about 8 cm apart the current density was 0.5 to 0.7 amp. After 50-55 hours the reducing power of the solution was negligible, so the solution was filtered, evaporated as far as possible, and left to solidify. The gelatinous mass was powdered and dried. The original papers should be consulted for preparation of crystalline calcium mannonate. To obtain the lactone of D-mannonic acid one part of the calcium salt is dissolved in 3 parts of water on the water-bath, an excess of oxalic acid is slowly added, the precipitated calcium oxalate is filtered off, and the filtrate is concentrated until its weight equals that of the calcium salt used this material is then left to crystallize. 

Aldonic adds monocarboxylic acids derived from aldose sugars by oxidation of the aldehyde group. The names of these adds are formed by replacing the -ose of the parent aldose with -onic add . A. a. may form a 1,4-lactone ring (y-lactones) or the more stable 1,5-lactone (6-lactones). Some important A. a. are L-arabonic add, xylonic acid, i>-g)uconic acid, D-mannonic acid and galactonic add. 

D-Glucono-5-lactone has been transformed in several steps to the protected pipecolic acid ester derivative 31 which, on reduction with lithium aluminium hydride, then hydrolysis, gives 1-deoxymannojirimycin. Hydrolysis only of 31 provided the iduronidase inhibitor 2,6-imino-D-mannonic acid. ... 

Solvents have a definite effect on the equilibrium composition. Thus, mannonic acid dissolved in acetic acid with 16 % of water shows a higher positive rotation than in water. The mutarotation is slower, but there is apparently a greater conversion to the 6-lactone than to the 7-lactone. The pH, temperature, and concentration also have an effect on the final equilibrium. 

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