Ryan anp Exsriti—The Synthesis of Glycosides. 249 
which has been given by Stone! and Bader’ for the similar 
substance prepared by them from the interaction of xylose and 
acetic anhydride. 
Though the constitution of our acetyl-chloro-pentoses remains 
unestablished, unless we assume that since the acetyl-chloro- 
arabinose is converted by methyl alcohol into a methyl-arabi- 
noside which Purdie and Rose regard as an a-derivative, the 
parent-substance must be an a-compound, we can nevertheless 
regard the phenolic derivatives of them as (3-compounds, since 
it has been shown by Fischer and Armstrong that both a and 3 
acetyl-chloro-hexoses give in alkaline solution (6-hexosides only. 
All the glycosides obtained from acetyl-chloro-hexoses in alka- 
line solution are, when the hexose is a fermentable one, with 
the single exception of the synthetical cane-sugar,? capable of 
being hydrolysed by emulsin. 
The phenolic compounds of non-fermentable sugars, such as 
the pentoses, are not hydrolysable by emulsin.‘ 
In an unsuccessful attempt to isolate the disaccharide of 
amygdalin by the action of emulsin on the heptacetyl deriva- 
tive of the glucoside, it was found by the authors’ that the 
conversion of the hydroxyl groups of a glucoside into the cor- 
responding oxyacetyl groups rendered the substance incapable of 
being hydrolysed by emulsin even when the solubility of the 
acetyl compound was increased by addition of a moderate amount 
of alcohol. Caldwell and Courtauld’ have recently confirmed 
our results with regard to the inactivity of emulsin towards 
the acetyl-derivatives of the glycosides. 
Preparation of Acetyl-chloro-xylose. 
Well-dried xylose (5 grams) and acetyl chloride (10°5 grams) 
were placed in a sealed tube, and the tube was then immersed in 
1 Amer. Chem. Jour., vol. xv., p. 653. 
*Chem. Zeit., Bd. xix., p. 55. 
3 Marchlewski, Anzeiger Akad. der Wissensch., Cracau, 1899. 
+ Ryan and Ebrill, Proc. Roy. Irish Acad., 1906, vol. xxvi., Sec. B., p. 53. 
© Tbid. 
6 Jour. Chem. Soc., 1907, vol. xci., p. 671. 
