TRANSACTIONS OF SECTION B. 635 



3. MiUarotation in relation to the Lactonic Structure of Glucose. 

 By E. Frankland Armstrong, Ph.D. 



Experiments have iDeen made whicli show that the hydrolysis of /3-methyl- 

 glucoside by emulsin in its initial stages proceeds faster than the change of 

 rotatory power of the glucose formed ; it is accordingly possible to make optical 

 determinations of the hydrolysis at given time intervals, and then by the addition 

 of alkali stop the action" of tlie enzyme, and at the same time rapidly convert the 

 glucose into its stable form. On doing this a considerable rise in rotatory power 

 was observed, proving that the /3-glucoside yields on hydrolysis the modification 

 of glucoside of low rotatory power corresponding to Tanret's solid y-glucose. 

 Similarly, a-glucosides yield the modification of high rotatory power corresponding 

 to Tanret's solid a-gliicose. These two compounds are thus lactones and differ 

 only in respect of the groups attached to the terminal carbon atom. The mani- 

 festation of miitarotation is therefore dependent on the conversion of one or other 

 lactone modification into a mixture of both in equilibrium, which, as the rotatory 

 power of glucose is unaffected by small changes of temperature, is a constant at 

 ordinary temperatures. 



Glucose in solution is thus a mixture of two lactones ; it is possible that the 

 aldehydic form may also exist, but doubtful, as glucose does not show under 

 ordinary conditions many of the milder aldehydic reactions. It has been possible 

 to extend these results to other sugars — viz. galactose and maltose — with similar 

 results. 



From this point of view it is clear why, on the addition of hydrogen cyanide to 

 glucose, two glucoheptose derivatives are formed in unequal quantities. It is no 

 lonirer necessary to assume that the hydrogen cyanide combines selectively, as 

 must be done if it be supposed that it is directly added to an aldehyde. 



Horace Brown has suggested that there may possibly be a difference in the 

 physiological behaviour of a sugar in its initial and final optical condition. In the 

 case of the lactone formula, however, this is improbable, as the groups attached to 

 terminal carbon atoms, which undergo rearrangement, are not concerned either 

 in fermentation or enzyme action. 



Thus, experiments made on tlie hydrolj'sis of millc sugar by lactase failed to 

 reveal any change in the initial velocity of hydrolysis, whether a fresh solution or 

 one wbicii had been boiled and stood overnight was used. 



4. Synthesis of Glucosides. By W. Sloan Mills, M.A. 



The first known instance of the synthesis of a glucoside occurring in nature 

 was effected by Michael, who, having prepared helicin from acetochloroglucose and 

 sodium salicylic aldehyde in absolute alcohol solution, reduced it with sodium 

 amalgam and obtained salicin. Eugenol and phenol glucosides and also methyl- 

 arbutin were prepared by Michael.^ His method was somewhat modified by Ryan,- 

 who prepared o- and p-cresol glucosides, and also carvacrol glucoside, which con- 

 tains an unchanged phenolic hydroxyl group. Glucosides of the alcohols and 

 mercaptans have been prepared by Fischer ^ by the action of the alcohol or 

 mercaptan on the sugar in presence of hydrochloric acid. A series of crystalline 

 a and (3 acetochloro- and acetobromo-glucoses have recently been obtained by 

 Fischer and Armstrong,'' by which the synthesis of many alkyl and phenol 

 glucosides has been effected. They have also prepared acetodibromoglucose, 

 which Professor Fischer allowed me to use with a view to preparing glucosides 

 containing a bromine atom in the glucose rest, and also amidoglucosides. 



' Comjit. Rend. (1879), 89, 355 ; and Am. Cliem. J. 5. 6, 336. 



2 J. C. S. (1899) 75, 1054. 



» Ber. (1893) 26, 2400 ; (1894) 27, 674, 2483, 2985. 



* lUd. (1901) 34, 2885. 



