The constituents of Withania somnifera / by Frederick B. Power and Arthur H. Salway.

  • Frederick Belding Power
Date:
[1911?]
Catalogue details

Licence: In copyright

Credit: The constituents of Withania somnifera / by Frederick B. Power and Arthur H. Salway. Source: Wellcome Collection.

    10/22 page 497
    some amorphous, resinous material. The chloroform solution was then washed, dried, and the solvent removed, when a viscid, brown residue was obtained, which, on agitation with alcohol, deposited a colourless, crystalline compound. This compound, amounting to 5 grams, was collected, and recrystallised from a mixture of chloro¬ form and alcohol, when it separated in colourless needles, which sintered at 285° and completely decomposed at 305°: 0*1081 gave 0*2866 C02 and 0*0816 H20. C-72‘2; H = 84. 0-1022 „ 0*2703 C02 „ 0*0750 H20. 72-1; 11 = 8*2. The molecular weight of the substance was determined by the cryoscopic method: 0*3170, in 28*16 nitrobenzene, gave \t= — 0*191°. M.W.=412. C25H34O5 requires C = 72*5; 11 = 8*2 per cent. M.W. = 414. No compound of the empirical formula C25H3405, possessing properties identical with those of the above substance, has hitherto been described. It is therefore proposed to designate the new compound withaniol, with reference to the generic name of the plant from which it has been obtained. Withaniol, C25H3405, is readily soluble in chloroform, only moderately so in alcohol, and practically insoluble in ether or light petroleum. It dissolves in cold concentrated hydrochloric acid, and is precipitated unchanged on the addition of water. It under¬ goes some change when heated with alkalis in the presence of alcohol, since the solution becomes deep red, and deposits, on acidification, a red, amorphous precipitate. When dissolved in a mixture of acetic anhydride and chloroform, and a drop of con¬ centrated sulphuric acid subsequently added, a pink coloration appears, which gradually changes to a straw-yellow colour. Withaniol is optically active, a determination of its rotatory power giving the following result: 0'3745, made up to 20 c.c. with chloroform, gave aD -fS0^7 in a 2-dcm. tube, whence [a]D + 91*2°. Withaniol contains no methoxy-group, but the presence of one hydroxyl group was proved by the formation of a monoacetyl derivative. Acetylwithaniol, C^HggOg’CO’CHg.—This derivative was prepared by heating withaniol for some time with an excess of acetic anhydride. On cooling the solution, the acetyl compound was deposited in the form of colourless, prismatic needles. After re¬ crystallisation from acetic anhydride, it began to melt at 280°, and at 300° became completely decomposed: 0-1032 gave 0*2675 C02 and 0*0750 H20. 0 = 70*7; H = 8T. 0*1122 „ 0*2920 C02 „ 0*0832 H20. 0 = 71*0; H = 8*2,
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