SYNTHETIC WORK IN CARBOHYDRATES 335 
From all sources the number of simple sugars, from the be¬ 
ginning of the century to less than ten years ago, numbered 
not over 6. Now, by means of synthetical research, not less 
than 30 simple sugars are known, and 7 of them are natural 
products. Among the 7 carbon-atom sugars, by calculating 
the possible number of isomers, 32 are possible, of which only 
6 have thus far been obtained. Of the 128 possible nonose 
sugars, as yet but 2 have been made. 1 
To carry out the thought of the sugar-group development 
it will be necessary to give rapidly an outline of these sugars 
before summing up the methods which led to their synthesis. 
Under the mannite group are included grape sugar and 
sugars possessing the same chemical composition as grape 
sugar. The mannose sugars also come under this group, with 
their corresponding alcohols and acids. The right, left, and 
inactive mannose correspond to the d-l and i glucose. The 
right mannose is formed at the same time as the right fructose, 
by the careful oxidation of the alcohol mannite. It was first 
obtained in this way. It may be mentioned that mannite is 
found in manna. Mannose may also be obtained from the 
natural carbohydrates by hydrolytic reaction. If is also found 
in the fruit of many palms. A very cheap source of supply is 
from the shavings of vegetable ivory in the manufacture of 
buttons. In separating the right mannose from its solutions, 
its phenylhydrazone compound is used. This compound is 
very insoluble, and affords a characteristic test for this sub¬ 
stance. 
The left mannose is obtained from the left arabinose. 2 The 
arabinose compounds contain 5 atoms of carbon. The cyan- 
hydrine reaction in the sugar series, or Kiliani’s reaction, is 
the one employed in its formation. This method has opened 
the field to some of the most important discoveries in sugar 
synthesis. In this reaction prussic acid unites directly with 
sugar, 3 and in this way the number of carbon atoms in the 
1 The table shows the present sugar status. 
2 By right, left, and inactive acids, of course, is meant the effect of these 
compounds on polarized light. 
3 C 2 HOH(CHOH) 4 CHO + HCN=CH 2 OH(CHOH) 4 CHOH . cn+h 2 o. 
