234 A. I. RINGER AND EMIL J. BAUMANN 



pounds for identification, disubstituted hydrazines have been used with 

 excellent results in many cases. Thus, galactose forms a very characteristic 

 methyl phenylhydrazone with rnethylphenylhydrazine. Other characteris- 

 tic sugar compounds with the hydrazines are the diphenylhydrazone of 

 arabinose, benzoylphenylhydrazones, etc. 



Glucose, fructose and mannose form the same phenylosazone glucos- 

 azone as would of course be expected from their configuration, as previ- 

 ously noted (see page 231). 



As stated above, the asymmetrically substituted hydrazines do not 

 form osazones with glucose because they cannot act as oxidizing agents. 

 Fructose, however, already having a CO group present, is readily attacked 

 by them. 



The osazones and hydrazones, then, form an admirable means of isolat- 

 ing carbohydrates from a solution containing inorganic and organic sub- 

 stances, i. e., biological fluids, like blood, urine, etc. To recover the free 

 sugar from the hydrazone, Fischer , decomposed them with hydrochloric 

 acid into phenylhydrazine and sugar.. It was later discovered that boiling 

 them with benzaldehyde and water, in the case of the monosubstituted 

 hydrazones, or with formaldehyde, in the case of the disubstituted hydra- 

 zones, was advantageous (Heizfeld, Ruff and Ollendorf), for then, in- 

 soluble benzaldehyde phenylhydrazone or formylphenylhydrazone were 

 formed, and the phenylhydrazones could be removed by filtering off these 

 insoluble derivatives. 



C 6 H 12 5 :N . NH C 6 H 5 +C 6 H 5 CHO->C 6 H 12 O 6 +C 6 H 5 CH -N . NH C 6 H 5 

 Phenylhydrazone -f- benzaldehyde * sugar -(- benzaldehyde 



phenylhydrazone 



Sugars cannot, however, be so readily recovered from their osazones. 

 When the latter are treated with concentrated hydrochloric acid it will 

 remove both hydrazine groups, forming an osone: 



/o 



CH:N.KE C 6 H 5 C 



I |\H 



C:N.H C 6 H 5 C=0 



HOCH +2 HC1 + 2 H 2 O^HOCH + 2 C 6 H 5 NH.NH 2 .HC1 



HCOH HCOH 



HCOH HCOH 



! I 



CH 2 OH CH 2 OH 



Phenylosazone -J- hydrochloric acid osone -}- phenylhydrazine. hydro- 

 and water chlorid 



