L-Mannonic acid

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

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). 

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. ... 

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. - ... 

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. 

One very interesting case is that of L-rhamnose. Hart and Everett obtained not only the expected 5-keto-L-rhamnonic acid but also 5-keto-L-mannonic acid (5-keto-D-gulonic acid) this was the first reported instance in which a — CH3 group had been oxidized by bromine water to a — CHaOH group. The yields of the brucine salts of the two acids were... 

In the synthesis of L-mannonic acid (I), a second acid also is formed which is enantiomorphous with that obtained by the oxidation of glucose. The dibasic acid obtained by the nitric acid oxidation of the arabinose also is optically active. 

L-Glucose can be synthesized from L-arabinose by the Fischer-Kiliani synthesis, but the synthesis is long and tedious [42] due in part to the difficulty in separating L-gluconic acid from the preponderant L-mannonic acid. In contrast, the synthesis of L-glucose by the addition of nitromethane to L-arabinose results in the formation of two epimeric 1-nitroalcohols that are readily separated by fractional crystallization [43]. This results in the synthesis of L-glucose (reaction... 

Sugar Acids and their Derivatives.- W-(l-Octyl)-D-talonamide,i03 Af-[8-(D-gluconamido)octyl]-D-gluconamide,lO L-mannonic acid hydrazide.lO 3,5(R) 6,7(R)-di-0-benzylidene-D-g(yccro-D-gM/o-heptono-l,4-lactone,lO 2-oxobutylbutyrolactone 38 02 and derivatives 39 and 40a/b 2 (all derived from condensation of ascorbic acid with methyl vinyl ketone and it should be noted that the structural deteimination of 39 served to c< rect an earlier... 

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