Chemical examination of Ipomoea purpurea / by Frederick B. Power and Harold Rogerson.

  • Power, Frederick B. (Frederick Belding), 1853-1927.
Date:
[1908?]
Catalogue details

Licence: In copyright

Credit: Chemical examination of Ipomoea purpurea / by Frederick B. Power and Harold Rogerson. Source: Wellcome Collection.

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    V. Alcohol Extract of the Resin. This constituted by far the largest proportion of the total resin, and, when dry, could readily be reduced to a very light brown, mo¬ bile powder. In order to insure the freedom of this resin from substances sol¬ uble in water, it was dissolved in alcohol and reprecipitated by the addition of water. Its further purification was effected by heating the alcoholic solution with a little pure animal charcoal. After fil¬ tering the liquid and removing the solvent a very light colored prod¬ uct was obtained, which, when dry, could be reduced to a perfectly white powder. The resin, purified as above described, after being dried at no0 C. was found to soften at 140° C., and to melt somewhat indefinitely between I 50 and 160° C. When heated on platinum-foil it fuses, chars, and burns with a smoky flame, leaving finally no visible resi¬ due. With cold, concentrated sulphuric acid it gives only a light brown color, whereas with nitric acid no coloration is produced. The optical rotatory power of this purified resin was determined in the same manner as has been described in connection with the crude resin. An alcoholic solution containing 13070 gramme of the resin in 25 c.c. had an initial rotation of — 2-7° in a I dcm. tube, whence [a]D — 51-64°. With the endeavor to ascertain whether this resin is homogeneous in character, 10 grammes of it were dissolved in 100 c.c. of alcohol, and to this solution was added an alcoholic solution of lead acetate. As no precipitate was produced, an alcoholic solution of ammonia was subsequently added in slight excess, when an abundant precipi¬ tate was obtained. This precipitate was collected, well washed with alcohol, then suspended in alcohol, and decomposed by hydrogen sulphide. After the removal of the lead sulphide by filtration, the liquid was concentrated to a small bulk, and ether added to precipi¬ tate the resin, which was subsequently dissolved in a little alcohol, the solution evaporated, and the residue dried. The weight of the resin which had thus been precipitated by the basic lead acetate was 6 grammes. The alcoholic filtrate from the basic lead acetate precipitate was deprived of lead by means of hydrogen sulphide, and, after filtration, concentrated to the consistency of a syrup. On the subsequent addition of ether a quantity of resin was precipitated,