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.

    10/16 (page 77)
    detailed examination. The bulk of the acid was evidently a lactonic acid, since 1 g. required 6*15 c.c. of A-sodium hydroxide for neutral¬ isation in the cold and 10*74 c.c. when heated with the alkali (C8Hi204 requires 5-8 c.c. of A-sodium hydroxide for neutralisation of one carboxyl group and 11-65 c.c. for conversion into the corre¬ sponding hydroxy-dicarboxylic acid C8H1405). The silver salt prepared from the disodium salt contained Ag, 53-6% (Calc, for €8H1205Ag2 : Ag, 53-4%) (Found for lead salt: C, 24-9; H, 3-7; Pb, 52-3. C8H1205Pb requires C, 24-3; H, 3-0; Pb, 52-4%). On regeneration from the lead salt by treatment with dilute sulphuric acid and extraction with ether, the original lactonic acid was obtained as an oil, which slowly solidified when kept in a vacuous desiccator; it then melted at 58—60° (Found : C, 55-75; H, 7-0. C8H1204 requires C, 55-9; H, 7-0%). On further oxidation with potassium permanganate, this lactonic acid, C8H1204, was converted into Z-isopropylsuccinic acid, which was isolated and identified as described above (p. 76). This stage of the oxidation of a-phellandrene is represented by formulae VIII, XVI, XI, XII and XIII (p. 73). On keeping the liquors from which the semicarbazone, m. p. 187°, was separated, for 2—3 days, a second semicarbazone was obtained the yield of which varied from a mere trace to as much as 20%. It crystallised from alcohol in small, colourless needles, m. p. 183°, Md* + 55-47° in acetic acid (c = 2-08) (Found : C, 54-8; H, 8-0; N, 17-8. CnH1903N3 requires C, 54-8; H, 7-9; N, 17-4%). A mixture with the first semicarbazone melted at 168—174°. The solubility of these two semicarbazones in alcohol is about the same, 0*2% at 15°; a mixture of the two is more soluble and very difficult to separate. The carbonyl compound was obtained from the semicarbazone by the method already described (p. 76). It did not crystallise but distilled unchanged at 155—160°/1 mm.; [a]§* 4- 73-67° in water (c — 1-775) and 4~ 54-79° in benzene (c = 1-566) (Found : C, 65-1; H, 9-0. C10H16O3 requires C, 65-2; H, 8-7%). It dissolves to a neutral solution in water, but this solution neutralises sodium hydroxide, 1 g. of the substance requiring 5-36 c.c. of A-sodium hydroxide (C10H16O3 requires 5-44 c.c. for conversion into the ketohydroxy-acid, C10H18O4). The substance is therefore a Jceto- lactone, C10H16O3. When this keto-lactone (1-7 g.) was oxidised with alkaline hypo- bromite as described above, bromoform was produced and an almost quantitative yield (1-5 g.) was obtained of an acid which after recrystallisation from benzene melted constantly at 138° and had [«]§’ 4- 15-99° in aqueous sodium hydroxide (c = 4-196), It was