200 A GENERAL REVIEW OF 



THE ALKYLATION OF DISACCHARIDES 



The preparation of derivatives of disaccharides is a matter 

 of difficulty on account of the readiness with which they 

 undergo hydrolysis and of the insolubility of these substances 

 in solvents other than water. The former difficulty does not 

 apply to alkylation by means of the silver oxide reaction, and 

 in the case of cane sugar, the solubility difficulty has been 

 overcome by Purdie and Irvine (19, 22, and 30) by a method 

 described in the Introduction. The materials were used in 

 the following proportions : cane sugar (1 mol.), methyl iodide 

 (20 mols. ), silver oxide ( 10 mols. ). Four alkylations with these 

 proportions were necessary for the production, from ten grams 

 of sucrose, of an equal weight of a neutral, syrupy liquid. 

 This product received no purification beyond drying in a 

 vacuum, but nevertheless gave analytical figures approximat- 

 ing to those required for an octamethylated sucrose. Hydro- 

 lysis of this substance by means of dilute, aqueous hydrochloric 

 acid gave a syrup which reduced Fehling's solution and from 

 which crystalline tetramethyl glucose has been obtained by 

 simple nucleation. The uncrystallised portion of the last- 

 mentioned syrup doubtless contained tetramethyl fructose, 

 but the difficulties encountered in this work have so far pre- 

 vented its isolation in a pure state. The results described are 

 of considerable significance, since they afford direct experi- 

 mental evidence of the correctness of Fischer's formula for 

 cane sugar. According to this formula, cane sugar possesses 

 a structure analogous to that of the alkylglucosides : 

 



CH 2 (OH) . C . CH(OH) . CH(OH) . CH . CH 2 OH 



A 



L. 



CH(OH) . CH(OH) . CH . CH(OH) . CH 2 OH 

 



