THE DISACCHARIDES. 9 
1. CH 2 OH[CH(OH)] 3 CH(OH)COH + H 2 N.NH(C 6 H 5 ) 
(dextrose) (phenylhydrazine) 
CIl.,OII[ClI(o]I)].Cli(<>II)CIl 
II +H 2 
jS t -NH(C II-) 
(hydrazone) (water) 
2. CHoOH[CH(On)], ) CH(OH)CII 
|| +C 6 H 5 .NH— NH, 
N-NH(C 6 H 5 ) 
(hydrazone) (phenylhydrazine) 
CH 2 OH[CH(OH)] 3 C— CH 
1 || +H, +!!.,< ) 
C C H 5 .NH— Js T N— NH.C 6 H 5 
(osazone) (hydrogen) (water) 
The hydrogen seen in the second equation is not really set free, but 
it is used to split up a further molecule of phenylhydrazine into aniline and 
ammonia (N E 2 — NH.C 6 H S + H 2 = NH.C^ + NH 3 ). 
In order to obtain the sugar from the osazone again, it is first 
treated with fuming hydrochloric acid. 1 This gives rise to phenylhy- 
drazine and a so-called osone. An osone is a substance which, besides 
the ketone group, contains an aldehyde group as well : CH.,OH — (CH.OH) 3 
_CO— COH. 
By means of zinc and acetic acid the osone is easily reduced to sugar. 
Glucosamine. — A derivative of glucose which is of some physiological 
interest is amido-glucose or glucosamine, C H 11 O-.NH. ) . This is obtained on 
the decomposition of chitin and chondroitin. By treatment with nitrous acid 
it passes into dextrose — 
C 6 H n 5 .NH 2 + XOOH = C H 12 O 6 + N 2 + H 2 
( ilucosamine can also be obtained by treating phenylglucosazone directly with 
reducing agents — 
C 6 H 10 O 4 .(X 2 H.C,H.) 2 + H 2 + H, = C II u O 5 .NH 2 + 
(phenylglucosazone) (glucosamine) 
NH 2 — jS t H.C q H 5 + NH.,C S H 5 
(phenylhydrazine) (aniline) 
This shows us another way of regenerating the sugars from their osazones. 2 
Further particulars about glucosamine will be found in connection with chitin 
and cartilage. 
The disaccharides. — A disaccharide is a condensation product of 
two molecules of the simple sugars or monosaccharides, the change being 
attended with the loss of a molecule of water:— 
C 6 H 12 6 + C 6 H 12 6 - Cj.H.oOn + H,0 
Thus— 
Cane-sugar is derivable from dextrose and levulose ; 
Milk-sugar, or lactose, from dextrose and galactose ; 
Maltose, from dextrose and dextrose. 
The general properties of these sugars are like those of the monosac- 
1 E. Fischer, Ber. d. deutsck. chem. Gesellsch., Berlin, 1888, Bd. xxi S. 2631; 1889, 
Bd. xxii. S. 87; 1890, Bd. xxiii. S. 2118. 
- E. Fischer, ibid., Berlin, Bd. xix. S. 1920 ; Fischer and J. Tafel, ibid., Bd. 
xx. 8. 2569. 
