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.

    20/30 (page 18)
    0*7238, mad© up to 20 c.c. with chloroform, gave aD +1°34/ in a 2-dcm. tube, whence [a]D +21*64°. The sugar obtained by hydrolysing a small portion of the above- described acetyl derivative yielded an osazone melting at 180—182°, but this was not identical with rhamnosazone, for a mixture of the two compounds melted at 163—164°. Moreover, on acetylating a quantity of pure rhamnose no crystalline derivative could be obtained. For the purpose of comparing the properties of the sugar yielding the above-described tetra-acetyl derivative with those of rhodeose, a small quantity of the latter was kindly supplied to us by Professor E. Yotocek, of Prague. This substance was in colourless, prismatic needles, melting at 144—145°, but the acetylated product could only be obtained in the form of a syrup. It may, furthermore, be noted that the phenylosazone of rhodeose has been recorded as melting at 170° (Ghem. Gentr., 1900, I., p. 803). a'soRhodeose yields an osazone melting at 186—187°, but the benzoylated product could not be obtained in a crystalline state (YctoJ-tk, Ber., 1911, 44, 820). In order to ascertain whether the methylpentose con¬ tained in the above-mentioned syrup was capable of yielding a crystalline benzoyl derivative, portions of the syrup were treated by both the Schotten-Baumann method and by heating with benzoic anhydride, but in each case with a negative result. After the separation of the above-described tetra-acetylmethyl- pentose, the mother liquors yielded a further quantity of the same substance, and finally a more readily soluble solid was deposited. This was collected, washed with a little dilute alcohol, and then recrystallised from 70 per cent, alcohol, when it separated in slender needles, melting at 111—112°. After two further crystallisations the substance began to melt at 112°, but complete fusion only took place at 118°. (Found, C = 49*2; H = 5*7. Calc., C = 49*2; H-5 6 per cent.) This compound was thus identified as penta-acetyldextrose, c6h7o6(co-ch3)6, and it apparently consisted of a mixture of the a- and /3-forms, which melt at 112° and 134° respectively. From the above results it is evident that by the acid hydrolysis of the ethyl acetate-soluble portion of the hydrolysed ethereal extract of the resin, two sugars are produced, one of which is dextrose, and in predominating amount, whilst the other is a methyl- pentose.