Mannonic acid phenylhydrazide

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... 

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 hundred grams of pure mannonic phenylhydrazide, 80 g. of copper sulfate pentahydrate, one liter of water and 1 cc. of octyl alcohol (to control foaming) were boiled for five hours under reflux. The solution was cleared of copper as sulfide, of sulfuric acid as barium sulfate, and upon concentration to 75 cc. the lactone crystallized readily. Successive crops were obtained by concentration and treatment of the sirups with methyl alcohol. The total yield of pure lactone was 55.8 g. (90%). During the reaction there is a vigorous evolution of nitrogen and in the condenser droplets of benzene appear. 

---