202 A GENERAL REVIEW OF 



therefore possess an acetal structure, and inspection of the 

 above formula shows that it explains the production of 

 tetramethyl glucose, under the conditions mentioned. The 

 glucosidic linkage in maltose is thus confirmed. 



The methylated sugars are more stable than the parent 

 compounds, and so offer greater resistance to the destructive 

 action of condensing agents than the latter. The alkylated 

 sugars too are soluble in chemically indifferent solvents, and 

 would thus appear to be available for the synthesis of methy- 

 lated disaccharides. Tetramethyl glucose has, in fact, been 

 used for such a purpose (Purdie and Irvine (30) ). The sugar 

 was dissolved in benzene containing 0'33 per cent, of hydrogen 

 chloride, and the solution heated in a sealed tube at 105-115 C. 

 for ten hours. The product was a syrup which was subjected 

 to two further treatments similar to the above. The resultant 

 viscid liquid was purified by distillation in a vacuum, and was 

 found to have no action on Fehling's solution. Condensation 

 had evidently occurred, and the product proved to be an 

 octamethyl glucosidoglucoside of the structure : 



vxj-j-g 



L. 



CH 2 . OCH 3 CH 2 . OCH 3 



.OCH, 



(CH . OCH 3 ) 2 

 CH 



The formula represents three stereoisomerides, the aa-, 

 and aj8-varieties, and the substance obtained was probably 

 a mixture of all three modifications. This was the first 

 recorded instance of the synthesis of a derivative of a non- 

 reducing disaccharide, and a similar method of self-condensa- 

 tion has recently been adopted by Fischer for the preparation 

 of disaccharides (Ber., 1909, 42, 2776). 



