The constituents of taraxacum root / by Frederick B. Power and Henry Browning, jun.

  • Power, Frederick B. (Frederick Belding), 1853-1927.
Date:
1912
Catalogue details

Licence: In copyright

Credit: The constituents of taraxacum root / by Frederick B. Power and Henry Browning, jun. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    from human urine, has, however, also noted that its aqueous solu- tion gives with ferric chloride a slight violet coloration. A quantity of the synthetic acid was accordingly prepared from phenylacetic acid, the latter having first been ‘ nitrated according to the method of Maxwell (Ber., 1879, 12, 1765). After very prolonged fractional crystallisation from warm water, a product was obtained which melted at 152°, the pure p-nitrophenylacetic acid having been observed by Maxwell (loc. cit.) to melt at 150°, and by Bedson (Trans., 1880, 37, 91) at 150—151°. This nitro-acid was reduced by tin and hydrochloric acid, and then, by means of the diazo-compound, converted into the corresponding hydroxy-acid. The acid thus prepared was found to have the same melting point as that obtained from taraxacum root, and when the two products were mixed no depression of the melting point ensued. The reaction with Millon’s reagent was precisely the same as that previously mentioned. On comparing the behaviour of the natural and the synthetic acid towards ferric chloride, it was observed in both cases that if a fairly concentrated solution of the acid were employed a faint and exceedingly fugitive violet coloration was produced, rapidly changing to greenish-brown, thus confirming the observa- tions of Salkowski and of Baumann (loc. cit.). The above results thus completely established the identity of the acid from taraxacum root with p-hydroxyphenylacetic acid. After the extraction of the original aqueous liquid with ether, as above described, it was shaken with eighteen successive portions of warm amyl alcohol. These amyl-alcoholic liquids were united, washed with water, concentrated under diminished pressure to the consistency of a syrup, and the last traces of amyl alcohol removed by passing steam through the liquid. The syrupy product was then further concentrated under diminished pressure, afterwards on a water-bath, and finally dried as completely as possible in a vacuum desiccator. There was thus obtained a quantity (42'5 grams) of a dark brown, viscous mass, which possessed a strongly bitter taste, and in aqueous solution gave a dark green colour with ferric chloride. Twelve grams of the above-mentioned product were heated for two hours with 5 per cent, sulphuric acid in aqueous alcohol. On subsequently distilling the mixture in a current of steam, a very small amount of a yellow oil was obtained, which gave the colour reaction of furfuraldehyde. The aqueous acid liquid was then extracted many times with ether, after which the sulphuric acid was removed by barium hydroxide, the excess of the latter by carbon dioxide, and the filtered liquid concentrated. From this syrupy product a small amount of an osazone (m. p. 210—211°) was