Saponarin : a new glucoside, coloured blue with iodine / by George Barger.

  • Barger, George, 1878-1939.
Date:
[1906?]
Catalogue details

Licence: Public Domain Mark

Credit: Saponarin : a new glucoside, coloured blue with iodine / by George Barger. Source: Wellcome Collection.

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    chloride and bright yellow by alkalis. Normal lead acetate does not precipitate it, but basic lead acetate gives a bulky, yellow precipitate. Saponarin is almost or quite insoluble in nearly all organic solvents. It dissolves to a small extent in hot glacial acetic acid and in aniline, more readily in the chloroacetic acids, in piperidine, quinoline, and phenylhydrazine; it is very soluble in pyridine. When heated slowly, it melts and decomposes at 231—232°, but if the bath is previously heated to 230° the melting point is 236°. The glucoside is laevorotatory. A solution containing 0 924 gram in 100 c.c. of pyridine gave aD-0*73c in a 1-dcm tube, whence [a]D-7*90°. The air-dried substance contains water of crystallisation which cannot be removed by heat alone, but which is completely expelled on standing for a week, at the ordinary temperature, in a vacuum over sulphuric acid, so that no further loss occurs when the substance is heated in a vacuum at 100°. The anhydrous substance is extremely hygroscopic; when left in the balance case for half an hour, it absorbs the whole of the water of crystallisation which it had lost. On this account some difficulty was at first experienced in analysing the anhydrous substance, and the boat had always to be weighed enclosed in a stoppered weighing bottle. The various samples were recrystallised two or three times by the pyridine-water method and dried in a vacuum. 0*1883 gave 0*3706 C02 and 0*0862 H20. 0*1446 0*1192 0*1714 0*1465 a 0*2846 COg 0*2358 C02 0*3380 C02 0-2898 C0o >> if ff 0*0675 H2G. 0*0559 H20. 0*0784 H20. 0*0653 H20. C = 53*68 ; H = 5*09. C = 5368 ; H = 5*19. C = 53*95 ; H = 5*22. 0 = 53-78 ; H = 5*08. 0 = 53*95 ; H = 4-95. C2iH240i2 requires 0 = 53*85 ; 11 = 5*13 per cent. The water of crystallisation in the air-dried substance was deter mined by drying in a vacuum until constant. At the ordinary temperature 0*1854 lost 0*0131 H„0 0*1580 0*3529 if if ff ff tf 0*0115 H20. if ff J5 >i At 100° 0*2553 if ff 0*0248 H20. 0*0181 H20. h2o 7*09. The air-dried substance was also analysed. 1. Obtained by exposing the moist substance to the atmosphere: 0*2166 gave 0*3942 C02 and 0*1105 H20. 0 = 49*64 ; H = 5*67. 2. Obtained by exposing the anhydrous substance to the atmosphere ; 0 1735 gave 0*3216 C02 and 0-0846 H20. 0 = 50*55 ; H = 5*42. C2iH240i2,2H20 requires H20 = 7*14. 0 = 50*00 ; H = 5*56 per cent. H20 = 7*07. H20 = 7*28. H20 = 7*03.