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.

    15/30 (page 13)
    Isolation of d-a-M ethylbutyric and Tiglic Acids. The above-mentioned distillate was a slightly opalescent liquid, amounting to about 8 litres. It was neutralised with sodium carbonate, and concentrated to a small volume, then acidified and extracted with ether, the ethereal liquid being dried and the solvent removed. A quantity (40 grams) of liquid acid was thus obtained, which, when distilled under the ordinary pressure, passed over between 160° and 200°, and it was observed that the last portions of the distillate, on cooling, solidified to a colourless, crystalline mass. Although the greater part of the solid acid, which was unsaturated, could be removed from the liquid portion by repeated fractional distillation, a complete separation could not thus be effected. In order, therefore, to obtain the liquid acid in a pure state, it was finally treated with potassium permanganate in alkaline solution at 0°. On subsequently recovering the unchanged acid, it was found to distil at 172—175°, and to possess the odour of a valeric acid. (Found, C = 58‘6; H = 100. Calc., C = 58‘8; H = 9‘8 per cent.) The density of the acid was 0'9392 at 21°, and a determination of its specific rotatory power gave the following result: aD, in a 25 mm. tube at 21°, = +4°8/, whence [a]D +17’6°. It was thus evident that the above-described liquid consisted of the optically active valeric acid (<i-a-methylbutyric acid), which had previously been obtained from several convolvulaceous resins. The solid acid which separated from the final fractions of the above-mentioned volatile acids was collected, and recrystallised from water, when it separated in flat needles, melting at 64—65°. By the slow evaporation of its ethereal solution it was obtained in large, well-defined prisms. It instantly decolorised an alkaline solution of potassium permanganate at 0°, and was therefore unsaturated. (Found, C = 59'9; H = 82. Calc., C = 60 0; H = 80 per cent.) This substance was thus identified as tiglic acid. The aqueous liquid, from which the above-described acids had been extracted with ether, was distilled in a current of steam. The distillate contained formic acid, together with apparently a little valeric acid. IS on-volatile Products of the Alkaline Hydrolysis.—After the removal of the d-a-methylbutyric and tiglic acids by distillation with steam, as above described, there remained in the distillation flask a dark yellow liquid, which was filtered and concentrated under diminished pressure to the consistency of a viscid syrup.