AND POLYHYDRIC ALCOHOLS 165 



TRIMETHYLATED GLUCOSES 

 2:3:5 TRIMETHYL GLUCOSE 1 



Up to the present, three isomeric trimethyl glucoses have 

 been prepared. One of these is the dimethyl methylglucoside 

 already described : the remaining two compounds are reducing 

 sugars which differ in the distribution of the methoxyl groups. 



It has already been shown by Purdie and Irvine that the 

 methylation of methyl glucoside gives trimethyl methyl- 

 glucoside as the main product when the reaction is carried 

 out in methyl alcoholic solution. Considering the mode of 

 preparation of this compound and the reactions of the tri- 

 methyl glucose obtained from it on hydrolysis, it is evident 

 that the primary alcoholic group present in the parent gluco- 

 side escapes methylation when the reaction is carried out in 

 presence of excess of alcohol. In solubility, reducing power, 

 optical activity, and general chemical character, including its 

 oxidation to a lactone, trimethyl glucose resembles tetra- 

 methyl glucose closely. Substitution of methoxyl for hydroxyl 

 in the three positions specified has therefore little effect on 

 the properties of glucose, and this result is important as it 

 will be afterwards shown that a change in the position of the 

 alkyloxy-groups results in the complete alteration of the optical 

 relationships. 



No doubt the method just described is capable of general 

 application as a means of obtaining trimethylated aldoses 

 containing an unsubstituted primary hydroxyl group, but the 

 risk of the product being contaminated with other derivatives, 

 and the experimental difficulties encountered in purifying 

 viscous syrups by vacuum distillation, have not induced us to 

 extend the method to other examples. 



1 This nomenclature for derivatives of sugars, although not yet adopted in standard 

 works of reference, seems specially advisable for the compounds described in this 

 paper. Inspection of the formula for monomethyl glucose will indicate the carbon 

 atoms to which the numbers refer. J. C. I. 



