Hydrazine, reactions with ketoses

Osones.—We are not yet done with the interesting reactions of these compounds for the osazones when warmed with concentrated hydrochloric acid, take up water and split off the two phenyl hydrazine residues and yield a compound containing both the aldehyde and the ketone groups of the original aldose and ketose sugars. The resulting compound is known as an osone. 

The influence, on the reaction, of different substituents in the phenyl-hydrazine molecule and the specificity due to these molecular changes have been studied. The specificity in respect to certain aldose configurations was proved, and it was also shown that D-fructose and other 2-ketoses react with such weakly basic hydrazines as (p-bromo-, (p-carboxy-, (p-carbeth-oxy- and (p-nitro-phenyl)hydrazine. Correlations between the reaction rate and ease of interconversion between cyclic and acyclic forms were also determined. Studies with tritium-labeled D-fructose showed that the... 

For selective oxidations in the carbohydrate field, Heyns and coworkers have investigated the use of platinum catalysts in different forms. For reactions in which further oxidation of the desired product is probable (as, for example, in the oxidation of ketose and pentose derivatives ), a milder catalyst of 5 to 10% platinum on activated carbon is recommended. Care must be taken in the preparation of the catalyst otherwise, it is difficult to obtain catalysts of reproducible activity. The platinum is deposited on the carbon by hydrogenation or by reduction with formaldehyde or hydrazine sulfate. The catalyst prepared through formaldehyde... 

The solubility characteristics of the reaction products of the sugars with unsubstituted hydrazine (NH2—NH2) are not favorable for identification purposes. The aldoses form aldazines, and the ketoses ketazines, in which 2 moles of the sugar are combined with 1 mole of the hydrazine 246). However, hydrazine reacts readily with sugar lactones to give characteristic derivatives useful for identification. The lactones may be regenerated from the hydrazides by treatment with nitrous anhydride 247). 

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