26 LECTURE II. 



corresponds to the formula Ci 8 H 2 2N 4 O4. This compound is known as 

 glucosazone. 1 It is formed by the action of two molecules of phenyl- 

 hydrazine upon one molecule of sugar, and in fact the reaction takes place 

 in two stages. First the sugar combines with one molecule of the base, 

 forming a hydrozone as follows: 



CH 2 (OH) [CH(OH)] 3 CHOH . CHO + C 6 H 5 NH . NH 2 = 

 CH 2 (OH) [CH(OH)] 3 .CHOH : N . NH . C 6 H 5 + H 2 O. 



* 



As this compound is very readily soluble in water, this phase of the 

 reaction is not noticeable in the reaction with glucose. 2 Then on warm- 

 ing with an excess of phenyl-hydrazine, the alcoholic group marked with 

 an * undergoes a peculiar oxidation. The group is changed into carbonyl, 

 CO, and is thus capable of combining with a second molecule of phenyl- 

 hydrazine, to form an ozazone of the formula: 



CH 2 OH[CH(OH)] 3 . C - CH 



II II 

 C 6 H 5 . HN . N N . NH . C 6 H 5 



As we shall soon see, fruit-sugar (fructose) instead of being an aldehyde, 

 is a ketone with the following structure: 



CH 2 OH 



1 



HO C H 

 H C OH 



H C OH 



I 



CH 2 OH 



Now it is possible to obtain exactly the same glucosazone from 

 fructose as from d-glucose, but in this case the two stages of the reaction 

 take place in the reverse order; the ketone being first acted upon then by 

 oxidation an aldehyde is formed, which reacts with a second molecule of 

 phenyl-hydrazine, as shown by the following scheme: 



CH 2 (OH) [CH(OH)] 3 .C CH 2 (OH) 



II * 



C 6 H 5 . HN . N 



CH 2 OH . [CH(OH)] 3 . C - CH 



II II 

 C 6 H 5 . HN - N N . NH . C 6 H 5 



1 Similarly we speak of galactosazone, arabinosazone, xylosazone, maltosazone, etc. 



2 With mannose difficultly soluble phenylhydrazone is formed and can be isolated. 



