— 179 — 



In order to split off the acetyl-groups, 4 g. of finely powdered 

 glucoside were heated 5 to 6 hours with a solution of 16 g. hydrated 

 baryta crystals in 240 cc. water and 75 cc. alcohol to 55 to 6o°, with 

 frequent stirring. The warm liquid was saturated with carbon dioxide, 

 the barium carbonate filtered off and washed with alcohol. The 

 filtrates, when evaporated, left in the vacuum a syrup studded with 

 white crystals, which for further purification was boiled with alcohol. 

 When the filtrate was evaporated a pale yellow, slowly congealing 

 syrup remained behind. This was dissolved in hot water and eva- 

 porated in vacuo, when the menthol-d-glucoside separated out 

 from it (2,4 g. = 87°/ of the theoretical yield). 



Analysis of the product, dried at 6o° under 15 mm., showed that 

 it contained 1 mol. water of crystallisation which was only completely 

 driven off after heating in vacuo to ioo°. The hydrous menthol-d- 

 glucoside melts gradually at yj to 79 , after mollifying first, and 

 is sparingly soluble in water, readily in alcohol, more sparingly in 

 benzene and almost insoluble in petroleum ether: Hd20° — 9I>9 to 

 93,0° (in alcohol). 



The glucoside is rather easily hydrolysable with emulsin. Thus, 

 0,3044 g. of the sample, which had been dissolved in 50 cc. and diluted 

 with 0,15 g. emulsin, after being left standing for 20 hours in the 

 incubator had yielded 88°/ of the theoretically possible quantity 

 of glucose. 



Tetra-acetyl borneol-glucoside C 10 H 17 O*C 6 H 7 O5(C 2 H 3 O) 4 , 

 was formed in exactly the same manner. It forms fine needles (from 

 alcohol) m. p. 119 to 120 . After saponification the d-borneol-d- 

 glucoside C 10 H 17 OC 6 H 11 O 5 was obtained. This body crystallises 

 from water in fairly large needles, m. p. 134 to 13 6°; [°Gd20 o — 42,1 

 to — 42,2° (in alcohol). Emulsin does not act very readily upon 

 the glucoside. After being left to stand for 3 days in the heating 

 stove only 40% na( i been hydrolised. 



Gluco-vanillin (vanillin-d-glucoside), described by Tiemann 1 ), 

 was prepared by a similar process. By shaking a solution of 1 o g. aceto- 

 bromo glucose in 75 cc. ethylic ether with a solution of 7,4 g vanillin 

 for 3 days in the calculated quantity of n-soda liquor, 6,9 g. of tetra- 

 acetyl-gluco-vanillin were obtained. When recrystallised from dilute 

 alcohol this body formed colourless, thin prisms, m. p. 143 to 144 . 

 After saponification gluco-vanillin was obtained which crystallised with 

 2 mol. water of crystallisation, in the same manner as does the pre- 

 paration obtained from coniferin: m. p. 188 to 189 , [«]d20° — 87,13° 

 (in water); according to Tiemann [«]d — 88,63°. 



*) Berl. Berichte 18 (1885), 1596. 



12* 



