The alkaloids of Picralima klaineana / by T.A. Henry and T.M. Sharp.

  • Henry, Thomas Anderson, 1873-1958
Date:
[1927.]
Catalogue details

Licence: Public Domain Mark

Credit: The alkaloids of Picralima klaineana / by T.A. Henry and T.M. Sharp. Source: Wellcome Collection.

    7/16 (page 1954)
    be precipitated completely from solution in acids by alkalis, nor can the alkaloid left in such alkaline filtrate be completely removed by any of the ordinary immiscible solvents. The yield of crude akuammine is about 0-6%. The four alkaloids are readily differ¬ entiated by their physical properties and colour reactions. Alkaloid A is insoluble in all ordinary solvents except acids and alkalis, and from these it is precipitated on dilution with water. Alkaloid B is readily soluble in all ordinary solvents except water, and solutions of its salts, unlike those of any of the other three, give an intense indigo-blue colour with ferric chloride. Akuammine (alkaloid C) dissolves in concentrated sulphuric acid without color¬ ation, but gives an intense blood-red colour, stable for several days, with nitric acid. The second crystalline alkaloid (D) gi\ es no colour with sulphuric acid but a vivid green, fading to yellow in a few hours, with nitric acid. In the following descriptions, the k£ melting points are corrected , in each case, except for akuammine hydrate, they are points at which the substance froths up the tube. I he temperature at which this occurs varies with the rate of heating, e.y., pure akuammine hydrochloride can be made to melt and decompose at an\ temper¬ ature from 215° to 227°. The melting points recorded for the base and its salts w'ere taken alongside the pure hydrochloride, melting at 227°, so that they are comparable among themselves. The optical rotations are for the dried substance in each case. Akuammine (Alkaloid C). The base is prepared by adding excess of sodium carbonate solution to a w^arm, aqueous solution of a purified salt. It is sparingly soluble in cold alcohol, but once dissolved in boiling alcohol it crystallises from the latter only by spontaneous evapor¬ ation in minute, colourless needles, m. p. 255 , [a]^ —GO 7 (in alcohol; c = 0*504) or -73*4° (in chloroform; c = 0-8716). It is rather more soluble in chloroform and sparingly soluble m acetone or ether (Found: C, 69*0, 69T ; H, 7*2, 70; N, r5. C22H2804N2 requires C, 68-7; H, 7*3; N, 7-3%). Akuammine hydrobromide, prepared like the sulphate (see abo\e), separates from dilute hot aqueous or alcoholic solutions in faintly grey long slender prisms, or from concentrated solutions in the same solvents in small needles, m. p. 228°, Mg’ -26-05° (in water; c _ 0-6076). The air-dry salt loses in a vacuous desiccator 3-61% and no further loss takes place in a vacuum at 100°. (Calc, for Co2H2804N9,HBr,H20 : H20, 3-7%. Found for dry salt : C, 56-1, 56-3 ; H, 6-0, 6-1; Br, 16-6. C22H2804N2,HBr requires C, 56 7; H 6-3; Br, 17-1%). The hydrochloride closely resembles the