Chemical examination of the root of ipomoea orizabensis / by Frederick B. Power and Harold Rogerson.

  • Frederick Belding Power
Date:
[1912?]
Catalogue details

Licence: In copyright

Credit: Chemical examination of the root of ipomoea orizabensis / by Frederick B. Power and Harold Rogerson. Source: Wellcome Collection.

    23/30 (page 21)
    Hydrolysis of the Ethyl Acetate Extract with Barium Hydroxide. A quantity (250 grams) of the ethyl acetate extract of the resin was dissolved in alcohol, a little water added, and subsequently a slight excess of a cold saturated solution of barium hydroxide. The hydrolysis was then allowed to proceed in precisely the same manner as described in connexion with the ether extract of the resin. After the hydrolysis was complete the filtered liquid was diluted with a large volume of water, and the alcohol removed by distillation in a current of steam. The barium contained in the solution was then exactly precipitated with dilute sulphuric acid, and the filtered liquid again distilled in steam until acid ceased to pass over. The distillate was rendered alkaline with sodium carbonate, concen¬ trated to a small volume, then acidified, and extracted with ether. The aqueous liquid remaining after this treatment was found to contain a considerable amount of acetic acid, but no formic acid. On subsequently evaporating the ethereal liquid, a quantity (15 grams) of a colourless liquid acid was obtained, which was distilled under the ordinary pressure, and the following frac¬ tions collected: (1) 100—125°; (2) 125—150°; (3) 150—170°; (4) 170—180°; (5) 180—185°; (6) 185—195°. The last fraction, amounting to O'5 gram, almost completely solidified. It was evident from the above results that the volatile acids consisted of a rather complex mixture. Fractions 1, 2, and 3 were each converted into three fractions of silver salt, the analysis of which indicated the presence of a considerable proportion of acetic acid with apparently some valeric acid. Fractions 4, 5, and the liquid portion of 6 were united, and treated in alkaline solution with potassium permanganate, as described in connexion with the volatile acids obtained by the hydrolysis of the ethereal extract of the resin with barium hydroxide. The amount of acid recovered after this treatment was 4'1 grams. It distilled between 173° and 175°, and possessed the following constants: D21 0'9320; aD +4°77 in a 25 mm. tube, whence [a]D -+-17'6°. (Found, C = 57'6; H = 9'7. Calc., C = 58'8; H = 9'8 per cent.) The above-described acid thus appears to have consisted chiefly of the optically active valeric acid, with a little acetic acid. The solid acid contained in fraction 6 was recrystallised from water, w7hen it separated in needles melting at 64—65°, and was identified as tiglic acid. (Found, C —60'0; II = 8'2. Calc., C = 60'0; II = 8 0 per cent.) The aqueous liquid remaining in the distillation flask after the removal of the above-mentioned volatile acids was filtered, and concentrated under diminished pressure to a syrup. The latter