The constitution of chaulmoogric and hydnocarpic acids / by Marmaduke Barrowcliff and Frederick B. Power.

  • Barrowcliff, Marmaduke.
Date:
[1907]
Catalogue details

Licence: In copyright

Credit: The constitution of chaulmoogric and hydnocarpic acids / by Marmaduke Barrowcliff and Frederick B. Power. Source: Wellcome Collection.

    6/26 (page 560)
    The formation of a tricarboxylic acid, C18H3206, possessing the same number of carbon atoms as chaulmoogric acid, shows that the ethylenic linking is contained in the ring, and not in an allylic grouping, as was previously supposed. The carbon chain •[CH^J^COgH contained in the keto-acid must be present in the original chaulmoogric acid molecule, and it therefore follows that the ring contained in the latter can consist of not more than five carbon atoms. As chaulmoogric acid, from the nature of its oxidation products, cannot be a trimethylene compound, it must contain either a methyl- crycfobutene or a q/c/opentene ring. The formation of the tricarboxylic acid would then be explained by assigning to chaulmoogric acid one of the following formulae : AJHMe. SCH- :CH, (I) CH<nu_>CH[CH2]12-C02H (II) CH: CEL •CH‘2 >CH[CH2]12-C02EL The product formed by the addition of hydrogen bromide to ethyl chaulmoograte is, as stated above, optically active, but on reducing this product with zinc dust and acetic acid the resulting ethyl dihydro- chaulmoograte is inactive. It is inconceivable, however, that racemisa- tion could be effected by a simple process of reduction when it is not brought about by treatment with hydrogen bromide or even by distil¬ ling the resulting product. From these considerations it seems highly probable that dihydrochaulmoogric acid no longer contains an asym¬ metric carbon atom, whereas if derived from formula I it would con tain two such carbon atoms. Moreover, the ketodicarboxylic acid, Ci^H3o05, if derived from a methylc?/cA>butene compound, would have the constitution C02H,CHMe*C0[CH;2]12,C02H, and would give on oxidation n-dodecanedicarboxylic and acetic acids, whereas it has been shown that malonic acid is formed and not acetic acid. From these considerations it follows that formula II may correctly be assigned to chaulmoogric acid. The tricarboxylic acid, c«hmo#, will therefore be n-pentadecane-aay-tricarboxylic acid, C02H-[CH2]2-CH-(C02H)-[CH2]12-C02H, and the constitution of the dihydroxydihydrochaulmoogric acid, which by its oxidation yields this tricarboxylic acid, may be represented by the formula : CH(OH)*CH(OH). CH0---CH, >CH[CH2]12-C02H. The tricarboxylic acid, although optically inactive, still contains an asymmetric carbon atom. The racemisation probably takes place in