The nature and origin of the poison of Lotus Arabicus / by Wyndham R. Dunstan and T.A. Henry.

  • Dunstan, Wyndham R. (Wyndham Rowland), 1861-1949.
Date:
1901
Catalogue details

Licence: In copyright

Credit: The nature and origin of the poison of Lotus Arabicus / by Wyndham R. Dunstan and T.A. Henry. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

    9/24 (page 521)
    potassium iodide formed. The insoluble portion was dissolved in hot methyl alcohol. This solution on cooling furnished yellow crystals melting at 125° C. These on re-crystallisation from a somewhat dilute solution in methyl alcohol gave a first fraction melting at 125° C. and a second melting at 175° C. As there appeared to be at least two substances present, a larger amount of the methyl ether was prepared and re-crystallised. Working with this new material it was found that two mutually convertible methyl ethers had been produced, one, the a-form, melting at 125° C., separating from solutions prepared by boiling the methyl ether with methyl alcohol in insufficient quantity for solution, and a second, the /3-form, melting at 175° C., and separating always as a second fraction, in largest quantity from more dilute solutions prepared by gently warming the methyl ether with excess of methyl alcohol. The a-methyl ether crystallises in rosettes of needles of a bright yellow colour, whilst the /3-form crystallises in long needles of an old-gold colour and silky lustre. The /3-form is more soluble in methyl alcohol than the a-form. It is somewhat remarkable that, although the transition point between the two forms must be lower than the boiling point of methyl alcohol (66° C.), since the /3-form is converted into the a-form by boiling with this solvent, yet the /3-form can be heated in the solid state without change far beyond the melting point of the a-methyl ether. During this operation the /3-form must be in a condition of labile equilibrium. A similar phenomenon is presented by sulphur, which in the rhombic form can be heated up to its melting point, 114-5° C., although the temperature of transition to monoclinic sulphur is only 95'4° C. The number of methoxyl groups present in the two methyl ethers was determined in the usual way by Zeisel’s method. a-methyl ether T196 gramme gave '2565 gramme silver iodide = 28-3 per cent. methoxyl. /3- s, T008 ,, 2139 ,, ,, = 28*07 per cent. methoxyl. Cl5H703(0CH3)3 requires 28*35 per cent. The substances are therefore isomeric trimethyl ethers. Action of Acetic Anhydride on the Trimetliyl Ether of Lotoflavin. Acetyltrimetliyl- lotofavin. Since lotoflavin yields a tetracetyl derivative, and therefore probably contains four hydroxyl groups, and yet only yields a trimethyl ether, it was of interest to determine whether the remaining hydroxyl group of the methyl ether could be acetylated. About 2 grammes of the a-modification of the trimethyl ether was dissolved in excess of acetic anhydride and the mixture warmed on the water-bath VOL. CXCIV.—B. 3 X