156 PREPARATION OF METHYLATED SUGARS 



one position the unmethylated reducing group. Considering 

 that methylation increases the stability of a sugar and also 

 confers a greater range of solubility on the product, it is 

 evident that partially methylated derivatives of the sugar 

 group would be compounds possessing a special interest. The 

 characteristic properties of the parent sugar would be more 

 closely preserved than in the case of a fully substituted 

 compound, a richer variety of reactions would be available, 

 and, at the same time, the more obscure decompositions under- 

 gone by sugars in virtue of the high hydroxyl content of the 

 molecule, would, to a large extent, be precluded. 



As examples of the many possible applications of such 

 compounds we have : (1) their use in testing the various 

 theories of alcoholic fermentation ; (2) their capacity to be 

 converted into mixed ethers of sugars or polyhydric alcohols, 

 compounds which possess a special interest for the physiologist; 

 (3) the accumulation of optical data showing the effect of 

 successive substitution in the sugar group, and (4) the oppor- 

 tunity afforded by the study of the mode of formation of these 

 compounds for obtaining experimental evidence of configura- 

 tion. 



Several examples of definite mono-, di-, and trimethylated 

 hexoses have been prepared by workers in St. Andrews during 

 the past three years, and, although the different lines of 

 research indicated above are not yet completely developed, 

 the work already done has furnished interesting results which 

 are now submitted, along with an estimate of the direction 

 which research in this field is likely to take. 



EXPERIMENTAL METHODS EMPLOYED 



The general method devised by Purdie and Irvine for the 

 preparation of fully methylated sugars does not permit of 



