432 



PHYSIOLOGICAL CHEMISTRY 



Yellow crystalline bodies called osazones are formed from certain 

 sugars under these conditions, in general each individual sugar giving 

 rise to an osazone of a definite crystalline form which is typical for that 

 sugar. 



It is important to remember in this connection that, of the simple 

 sugars of interest in physiological chemistry, glucose and fructose yield 

 the same osazone, with phenylhydrazine. Each osazone has a definite 

 melting-point, and as a further and more accurate means of identifica- 

 tion it may be recrystallized and identified by the determination of its 

 melting-point and nitrogen content. The reaction taking place in the 

 formation of phenylglucosazone is as follows : 



CH 2 OH 



(CHOH); 



CHOH 



y 



C 

 \H 



Glucose 



CH 2 OH 



+C 6 H 6 NH-NH 2 - 



CH 2 OH 



I 

 (CHOH) 3 



CHOH 



+C 6 H 6 NH NH 2 - 



Phenylhydrazine 



C 

 \H 



Phenylhydrazone 



CH 2 OH 



(CHOH) 3 

 C=0 



+C 6 H 6 NHNH 2 - 

 NHC 6 H 5 + C 6 H 5 NH 2 +NH 3 



C 



\ 



H 



Aniline 



Ammonia 



(CHOH) 3 



C = NNHC 6 H 5 

 [yN-NHCeH, 



C 



Glucosazone 



(b) Place 5 c.c. of the urine in a test-tube, add i c.c. of phenylhydrazine- 

 acetate solution furnished by the instructor, 1 and heat on a boiling water-bath 

 for one-half to three-quarters of an hour. Allow the liquid to cool slowly and 

 examine the crystals microscopically (Plate HI, opposite page 22). 



The phenylhydrazine test has been so modified by Cipollina as to 

 be of use as a rapid clinical test. The directions for this test are given 

 in the next experiment. 



2. Reduction Tests. To their aldehyde or ketone structure, many 

 sugars owe the property of readily reducing the alkaline solutions of the 

 oxides of metals like copper, bismuth, and mercury; they also possess 

 the property of reducing ammoniacal silver solutions with the separa- 

 tion of metallic silver. Upon this property of reduction the most widely 



^ l This solution is prepared by mixing one part by volume, in each case of glacial acetic 

 acid, one part of water and two parts of phenylhydrazine (the base). 



