160 PREPARATION OF METHYLATED SUGARS 



removed simultaneously and apparently at the same rate. 

 After neutralisation with silver carbonate, shaking with animal 

 charcoal and concentration at 40/15 mm., a syrup was ob- 

 tained. The product was dissolved in methyl alcohol and 

 precipitated in the crystalline form by the addition of acetone. 

 Analysis showed the compound to be monomethyl glucose in 

 a state of purity. The substance shows all the characteristic 

 properties of a reducing sugar, melts sharply at 157-158 and 

 is more soluble in organic solvents than the parent glucose. 

 When crystallised as described the compound showed muta- 

 rotation : 



c=2-46, Solvent= methyl alcohol. [a] 2 D 0> +98'6 ^68-0. 



This form is accordingly regarded as the a-isomeride. 



The jS-form of the sugar has also been isolated by the 

 method subsequently described under dimethyl glucose. This 

 form showed the upward mutarotation +28 > +68, and the 

 optical values are thus in fair agreement with those calculated 

 by the method recently described by Hudson. 



The position of the methyl group in monomethyl glucose 

 was readily established as, on treatment with phenyl hydra- 

 zine and acetic acid, the sugar gave a monomethyl glucosazone 

 identical with that previously obtained from monomethyl 

 fructose. In the case of the latter sugar, direct experimental 

 evidence exists which indicates that the methoxyl group is 

 terminal. 



MONOMETHYL FBUCTOSE 



No detailed account of the isolation of monomethyl 

 fructose need be given here, as a description of the compound 

 is included in Mr. Young's contribution to this volume. The 

 method adopted was substantially the same as that followed 



