Notes on scientific research. 149 



The authors were also able to elaborate a simple method for preparing a-menthol- 

 glucoside, so that it is by far the easiest to produce of all artifical glucosides of the 

 aromatic and hydroaromatic series. 



When acetobromoglucose is allowed to react on Z-menthol in the presence of 

 quinoline at a temperature of 100 to 105° one obtains a mixture of tetracetyl compounds 

 and of derivatives of a- and /?-mentholglucoside which are more deficient in acetyl. 

 In order to reacetylate the latter completely one dissolves the raw material in pyridine, 

 adds the same quantity of acetic anhydride at a low temperature and lets it stand for 

 24 hours at room temperature. Hereupon one pours the product of reaction into ice 

 water, dissolves the liberated oil in ether, frees the etheral layer from pyridine by 

 agitating it with diluted sulphuric acid, from acetic acid by means of bicarbonate 

 solution, and finally evaporates it after washing it with water. The tetracetyM-menthol- 

 glucoside separates itself from the viscous residue in a crystalline state. Tetracetyl- 

 a-mentholglucoside remains in the mother liquor and can be eliminated by means of 

 an inoculation crystal (to be obtained from the triacetyl compound). Melting point 

 82 to 83°. 



As mentioned above, the reaction of acetobromoglucose with menthol in the 

 presence of quinoline also produces, besides the two tetracetyl compounds, substances 

 more deficient in acetyl of which the triacetyl compounds of «- and ^-menthol glucoside 

 can be isolated without much trouble. Triacetyl-/?-mentholglucoside melts at 143 to 

 146°, the a-glucoside at 99 to 100°. 



a-Z-menthol-d-glucoside is formed from the above-mentioned acetyl derivatives by 

 saponification with alkali in watery-alcoholic solution. Its preparation in a pure state is 

 very simple owing to its slight solubility in water. Its melting point in anhydrous state 

 is between 159 and 160° and it crystalizes out of water in large, thin square leaves. 



Owing to its slight solubility in water, the glucoside can also be easily prepared 

 without any intermediate products. Acetobromoglucose is heated with menthol and 

 quinoline for 2 hours at 100°, the mass is then dissolved in water and ether and the 

 etheral layer washed first with diluted sulphuric acid and than with bicarbonate. After 

 the ether has been evaporated one drives off the excess of menthol by the aid of 

 steam. The residual brown-red oil is easily separated from water when it has cooled 

 down. It is dissolved in warm alcohol, mixed at about 60° with seminormal caustic 

 potash solution, and the clear liquid then maintained for about 10 minutes at the 

 same temperature. On adding water the crystallization of the a-mentholglucoside 

 begins immediately, whereupon one cools the liquid down to 0° for about an hour 

 and filters it. Recrystallizing it once from diluted alcohol suffices to produce a quite 

 pure substance. 



Owing to the slight solubility of the glucosides in water one can easily hydrolyze 

 their solutions by heating them with a mixture of glacial acetic acid and seminormal 

 hydrochloric acid in a sealed tube. 



Sabindl. — Owing to the fact that very differing constants are mentioned in current 

 literature concerning sabinol and that it contains 3 asymmetrical carbon atoms which 

 presupposes the existence of 8 isomerides, V. Paolini and G. Rebora 1 ) have attempted 

 to separate them. They transformed sabinol which originated from the fractions of 

 saponified savin oil boiling from 200 to 215°, into its hitherto unknown phthalic acid 

 derivative, a substance crystallizing in white needles and melting at 94 to 95° (from 



l ) Atti R. Accad. dei Lincei, Rome (5) 25 (1916), II. 377; Chem. Zentralbl. 1917, I. 752. 



