XL. 
ON THE SYNTHESIS OF GLUCOSIDES. 
By PROFESSOR HUGH RYAN, M.A., D.Sc., F.R.U.L., 
University College, Dublin. 
[Read Aprit 17; Received for Publication, Aprit 19; Published Juny 20, 1901.] 
Or the many glucosides which occur in the vegetable kingdom 
very few have been obtained synthetically in the laboratory. 
Although the decomposition of a glucoside into its components is a 
comparatively simple operation, the reversal of the process is, in the 
vast majority of cases, very difficult. ‘T'wo of the three methods 
hitherto used for synthesis of glucosides are indeed reversible. it 
has been shown by Hill,t Emmerling,’ and Emil Fischer and Arm- 
strong’ that zymohydrolysis is a reversible operation. In this 
way Emmerling obtained isomaltose from glucose by the action of 
maltase, and Fischer galactasidoglucose from galactose, and glucose 
by the action of kephyr lactase. ‘The method has, however, given 
successful results only in the above two cases. The second process 
for hydrolysing glucosides, the action of hot dilute acids, is also, as 
has been shown by Emil Fischer, reversible. Many hexosides 
were got in this way from the various hexoses. By the action of 
strong, cold, or diluted hot hydrochloric acid on glucose and 
methyl alcohol, two methylglucosides were got thus :— 
C;H,,0;- CHO + HOCH, = 0©;H,,0; :CHOCH, + H.0. 
The one, a methylglucoside, is not acted on by emulsin, and 
is readily hydrolysed by yeast; the other is unacted on by 
yeast, and readily hydrolysed by emulsin, and was named by Fischer 
fs methylglucoside. Similarly ethyl, propyl, isopropyl, amyl, and 
benzyl alcohols gave corresponding glucosides. ‘The method was 
found applicable to the diatomic and triatomic alcohols as glycol 
and glycerol as well as ethyl, amyl, and benzyl mercaptans.* 
1 Trans. Chem. Soc. 73, p. 634 [1898]. 
2 Ber. 34 (1901), p. 600. 
3Sitz. der k. Akad. der Wissensch. zu Berlin, 1901. vii. p. 123. 
4 Ber. 26 (1893), p. 2400, 27 (1894) pp. 674, 2483, 2985. 
