Glucosazone from fructose

Now since the configuration of carbon atoms 3, 4 and 5 of glucose and fructose art identical, it folhjws that glucosazone and fructosazone are identical in all respects. The osazone is formed however more rapidly from fructose than from glucose, and this difference in rate of formation may be used to distinguish the two sugars, provided the reactions are carried out under strictly parallel conditions (pp. 138, 338). 

Sucrose likewise yields glucosazone identifiable as glucosazone formazan. This indicates that in sucrose it is the hydroxyl group on the first carbon atom of n-fructose which oxidizes to an aldehyde group. As has been observed by several authors (1, 7, 14), in the course of the formation of osazone the disaccharide bond 2, S) breaks up and glucosazone forms from both components of the disaccharide upon the addition of phenylhy drazine. 

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