SYNTHETIC WORK IN CARBOHYDRATES 323 



The polysaccharides are bodies made up from several sim- 

 ple sugar molecules, uniting with elimination of water. Thus 

 cane sugar may be converted into grape and fruit sugar by 

 hydroly tic reaction, as shown by the equation : 



C 12 H 22 O n +H 2 O =C 6 H 12 O 6 +C 6 H 12 O 6 ; 



consequently, the simple sugars, like glucose, appear as the 

 basis of the entire group. 



In nature, the simple sugars, or monosaccharides, are found 

 not only as carbohydrates, but they occur also in combina- 

 tion with phenols as glucosides. 



From the widely spread distribution of glucose, its uses as 

 a food product, and considered chemically as the basis of more 

 complicated carbohydrates, it deserves careful consideration. 



The name hexose, which is the general name for the glu- 

 cose group, as the word implies, shows that 6 carbon atoms 

 enter into the composition of the individuals of the group. 

 These carbon atoms are united in an open chain, each carbon 

 atom, except one at one end of the chain, being united to a 

 hydroxyl (OH) group. This end carbon atom is united with 

 hydrogen and oxygen, forming an aldehyde group which is 

 peculiar to these sugars. Glucose and sugars of its class are 

 represented by the constitution which expresses an aldose or 

 aldehyde sugar, CH 2 OH . (CHOH) n . CHO. 



Fruit sugar, or ketose, is expressed by the formula : 



CH 2 OH . (CHOH) n . CO . CH 2 OH. 



The reason for accepting this atomic arrangement to ex- 

 press the constitution of the glucose and fructose groups is 

 based upon several considerations. Grape and fruit sugar, 

 on reduction with hydrogen, yield the alcohol mannite. Galac- 

 tose, which is also an aldehyde sugar, under the same condi- 

 tions gives the alcohol dulcite. The 6 hydrogen atoms of the 

 hydroxyl groups of these alcohols are replaced by acetyl groups 

 on treating them with acetic anhydride, so they must be con- 

 sidered as the hexavalent alcohols of the above sugars. 



The aldehyde character of glucose and galactose is also 

 shown by their behavior towards oxidizing agents. On par- 

 tial oxidation, by chlorine or bromine water, they yield re- 



