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

  • George Barger
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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    considerable loss of weight. As in the case of saponarin, saponaretin is very hygroscopic, so that the boat had to be weighed while enclosed in a stoppered tube. 0-2062 gave 0-4412 C02 and 0-0853 H.O. C = 58*36 ; H = 4-60. 0-1221 „ 0-2595 C02 „ 0-0527 H20. C = 57-97 ; H = 4 78. C15H1407 requires C = 58*82 ; H = 4-57 per cent. When dried at 130—160°, the substance loses a little more water and corresponds with the formula C15H1206,-JH20, but prolonged heating at this temperature decomposes saponaretin, and in no case did it approxi¬ mate to the formula C15H1206. It may be that saponaretin is identical with Perkin’s homovitexin, to which he assigns the formula C16H]607 or 018H1808. Both sub¬ stances differ from vitexin in being readily soluble in boiling alcohol; the composition of saponaretin dried at 160° approximates to that of homovitexin. Both substances yield, on fusion with caustic alkali, phloroglucinol and jP-hydroxybenzoic acid. Both separate from the vitexin mother liquor on exposure to air as an amorphous product, but homovitexin was finally obtained by Perkin in a crystalline form. Decomposition by Caustic Alkali. Caustic potash (7 grams), to which a little water had been added, was melted in a nickel crucible and finely-powdered saponarin (16 grams) was gradually dropped in. The temperature was kept between 190° and 200°. After each addition of the glucoside, the fused mass was stirred with a platinum wire. The fused mass, which was dull red, was dissolved in water, acidified with hydrochloric acid, and extracted with ether; the ethereal solution was shaken with sodium carbonate and then evaporated. It left a minute quantity of a substance readily soluble in water, which reddened a pine wood splinter, previously dipped in hydrochloric acid; the presence of phloroglucinol was thus indicated. The sodium carbonate solution on acidification and extrac¬ tion with ether gave a crystalline acid, which was recrystallised from water containing a little animal charcoal and then melted at 210°. With ferric chloride, no coloration, but a yellow precipitate, was pro¬ duced. When rapidly heated, phenol was formed, and was detected by its odour and by the tribromophenol test. The substance was evidently y>-hydroxybenzoic acid. The quantity available was used for the determination of the water of crystallisation. ! 0-0574 of the air-dried crystals lost 0-0069 gram when heated to 110°. Hence H2O = 120. ChH603,H?0 requires HgO = 11 5 per cent.
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