Issued January 24, 1910. 



United States Department of Agriculture, 



BUREAU OF CHEMISTRY Circular No. 49. 

 H. W. WILEY, Chief of Bureau. 



A RELATION BETWEEN THE CHEMICAL CONSTITUTION AND THE 

 OPTICAL ROTATORY POWER OF THE SUGAR LACTONES. 



By C. S. HUDSON, Assistant Chemist. 



THE HYPOTHESIS. 



The numerous sugars are strongly rotatory. On the other hand, 

 the alcohols which result from their reduction and the acids which are 

 formed by their oxidation are only feebly rotatory. But the gluco- 

 sidic compounds of the sugars and the lactones of these acids are as 

 strongly rotatory as the sugars themselves. Thus, for example, the 

 specific rotations of the two forms of glucose are 109 and 20, of the 

 methyl glucosids 157 and 32, of gluconic acid lactone 68, but the 

 rotation of gluconic acid is only 2, and sorbitol, which is the alcohol 

 that results from the reduction of glucose, shows no rotation. Is 

 there any other property of these substances which varies in the 

 same manner as the rotatory power? 



The constitutional chemical formulas now in use for these com- 

 pounds have been chosen step by step to express their chemical 

 reactivities, and it is now generally agreed that the sugars, the glu- 

 cosids, and the lactones possess a lactonic ring, but that this is absent 

 from the structure of the alcohols and acids. Here, then, is a property, 

 namely, the chemical constitution, which runs exactly parallel with 

 the physical property of optical rotation in the case of the sugar 

 glucose. Does the same parallelism hold for the other sugars ? 



To answer this question reference may be made to Table 1, which 

 gives the specific rotations of the principal aldose sugars, and their 

 glucosidic, lactonic, acidic, and alcoholic derivatives, so far as they 

 are known; the numerical values are in all cases quoted from the 

 literature. 



19569 Cir. 4910 



