Action of Beckmann's chromic acid mixture on some monocyclic terpenes / by T.A. Henry and H. Paget.

  • Henry, Thomas Anderson, 1873-1958
Date:
[1928.]
Catalogue details

Licence: Public Domain Mark

Credit: Action of Beckmann's chromic acid mixture on some monocyclic terpenes / by T.A. Henry and H. Paget. Source: Wellcome Collection.

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    The a-phellandrene (VIII) used was purchased on various occa¬ sions in London and its botanical origin is unknown, although it was no doubt derived from one or other of the species used for the production of eucalyptus oil. All the samples yielded the same products on oxidation with Beckmann’s mixture, viz., thymo- quinone and two ketolactones, C10H16O3 and C9H1403, both of which were isolated in the form of their semicarbazones, which are separable from each other with great difficulty. The keto-lactone C10H16O3 (IX) is oxidised by sodium hypo- bromite, but instead of the dibasic hydroxy-acid or its lactone, which would be the normal product, a dibasic acid, C9H1404, is formed, which is readily oxidised further by potassium perman¬ ganate to a-^opropylsuccinic acid. Such a dibasic acid may arise from the dibasic hydroxy-acid by loss of water in two ways, to give either p-isopropyl-a^-dihydromuconic acid, C02H*CH2*CHPr^*CH:CH*C02H (Xo), which should readily absorb bromine (compare Baeyer and Rupe, Annalen, 1890, 256, 18), or, if carbon atoms 3 and 5 are involved, a cyc/opropane derivative (X6). Oxidation of either could give rise to zsopropylsuccinic acid, being preceded in the second case by hydration, as in that of dimethyldicycZopentanonedicarboxylic acid (Farmer and Ingold, J., 1920,117, 1369). The molecular refraction of the diethyl ester is closer to that calculated for the unsaturated structure, on the usual assumptions (Eisenlohr, “ Spectrochemie organischer Verbindungen,” 1912, p. 48), than to that for the cyc/opropane structure, but as we were unable to form any addition product with bromine the cyclic formula cannot be left out of account. The second keto-lactone, C9H1403, we propose to represent by formula (XI). It furnishes with sodium hypobromite bromoform and a lactone acid, C8H1204 (XII), which on further oxidation by permanganate yields a-isopropylsuccinic acid (XIII). The latter also occurs, as would be expected, among the direct oxidation products of a-phellandrene by Beckmann’s mixture, and it has already been obtained by Semmler (along with a-zsopropylglutaric acid : the latter being attributed to the presence of (3-phellandrene) by the oxidation of commercial phellandrene from eucalyptus oil with permanganate (Ber., 1903, 36, 1749). Semmler’s acid had m. p. 116°, was optically active, although no specific rotation is quoted, and gave an anilic acid, m. p. 143°; the melting point of the racemic anilic acid has been given as 145° (Bentley, Perkin, and Thorpe, J., 1896, 69, 274), 139° (Bone and Sprankling, J., 1900, 77, 658), and 135° (Crossley, J., 1902, 81, 682). The acid we have obtained has m. p. 95°, [a]D — 22-64 (sodium salt), and yields an