Ryan and Ebrill — IVie Sz/nthesis of Glycosides. 381 



stance (acctobromoglucose) by Koenigs aud Knorr' was au important 

 advance in the method of syuthesising glycosides. The pure, well- 

 crystallized acctobromoglucose was converted into /3-pcntacetyl 

 glucose, )8-methyl, y8-ethyl, ^-phenyl, ^-/3-naphthyl, and ;8-carva- 

 cryl-glucosides. 



A still further advance was made by the discovery of Fischer and 

 Armstrong,- that anhydrous liquid halogen acids react with a- and y3- 

 pentacetyl glucoses to form well-crystallized a- and /5-acetochloro and 

 acetobromoglucoses. In this way the acetochlorogalactose, obtained 

 as a sp'up by Colley's method,^ was isolated in the pure condition as 

 a well-crystallized compound, and converted into ^-phenyl galacto- 

 side. From the a-acetochloroglucose they obtained a-alkyl-glucosides, 

 and from /?-acetochloroglucose the corresponding /3-giucosides. The 

 failure of Fischer and Armstrong to convert acetohalogen pentoses into 

 phenol derivatives is probably due to the ease with which the a-com- 

 pound changes into the /3-derivative in the presence of dilute alkali.* 



By the action of phosphorous pentachloride and aluminium 

 chloride on the chloroform solution of a-pentacetyl-glucose and a-pen- 

 tacetylagalactose, crystallized a-acetochlorohexoses were obtained by 

 Skraup and Kremann.^ Acetochlorolactose was obtained by Bodart," 

 by the action of hydrochloric acid gas on dry lactose, suspended in 

 cold acetic anhydride, which, with its isomeride, was also obtained 

 by Fischer and Ai-mstrong. The latter chemists also converted the 

 analogous acetochloromaltose into ;8-methyl-maltoside. 



The j8-phenyl-maltoside obtained by Fischer and Armstrong'' from 

 /8-acetobromomaltose was hydrolysed by emulsine to maltose and 

 phenol. Its behaviour towards the enzyme is different fi'om that of 

 amygdalin, which is decomposed, on hydrolysis by emulsine into 

 glucose, benzaldehyde, and hydrocyanic acid. 



Although halogen derivatives have been most largely employed 

 for the synthesis of glycosides, it is interesting to note that nitro- 

 dcrivatives have also been successfully used by Koenigs and Knorr." 



1 Sitz. Bayr. Akad. der Wissensch., 1900, p. 103. 

 - Sitz. der K. Akad. der Wissensch., Berlin, 1901, xiii., p. 316. 

 3 Ryan, Journ. Chem. Soc, 1899, p. 1057 ; Proc. Eoy. Dubl. Soc, vol. vs.. 

 <N.s.), p. 506. 



■* Berichte, sxxiv., 1901, p. 2885. 

 ° Monatsch. f. Chem., xxii., p. 375. 

 ^ V. loo. cit. 



'• Berichte, sxxv., 1902, p. 3153. 

 * Berichte, xxxiv., 1901, p. 957. 



