PURDIE'S REACTION 205 



the corresponding sugar dimethyl rhamnose, which forms a 

 hydrazone but no osazone. Fischer's alternative formula 

 for acetonerhamnoside 



-0- 



Me . CH(OH) . CH . CH(OH) . CH . CH 



i A 



V 

 /\ 



Me Me 



is therefore also excluded, since, in methylating the sub- 

 stance, of the two C-atoms attacked one is evidently in the 

 a-position. It would appear that the second linkage of the 

 acetone residue is attached to the ft- or 8-carbon atom (Purdie 

 and Young (34) ). 



By methylating fructose diacetone by means of silver 

 oxide and methyl iodide, Irvine and Hynd (46) have obtained 

 clear evidence of the structure of that compound, which 

 evidently contains one hydroxyl group, since it yields only a 

 monomethylated derivative. The latter substance is easily 

 hydrolysed by dilute hydrochloric acid, giving a crystalline 

 monomethyl fructose possessing all the properties of a 

 reducing sugar. The sugar, when heated with phenyl- 

 hydrazine, gives monomethylglucosazone, and when oxidised 

 with bromine water, it is converted into a dihydroxymethoxy- 

 butyric acid which is incapable of forming a lactone. Con- 

 sideration of these results will show that the formula for 

 monomethyl fructose must be 



0-- 



HO . CH 2 . C(OH) . CH(OH) . CH(OH) . CH . CH 2 OCH 3 , 



