Action of Beckmann's mixture on some monocyclic terpenes. Pt. 2, Terpinolene and "origanene" / by T.A. Henry and H. Paget.

  • Henry, Thomas Anderson, 1873-1958
Date:
[1931.]
Catalogue details

Licence: Public Domain Mark

Credit: Action of Beckmann's mixture on some monocyclic terpenes. Pt. 2, Terpinolene and "origanene" / by T.A. Henry and H. Paget. Source: Wellcome Collection.

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    by the addition of two atoms of hydrogen. It is readily oxidised by permanganate to lsevulic acid (VII), and on prolonged treatment with Beckmann’s mixture at 60° it breaks somewhat unexpectedly between the two methylene groups, giving a quantitative yield of terebilic acid (VIII), the identity of which was confirmed by catalytic reduction to terebic acid (IX). Hydrolysis of the keto-lactone (III) takes place only on warming with alkali. The product is not the corresponding hydroxy-acid, but an unsaturated acid, which is represented by formula (V), since on reduction it absorbs four atoms of hydrogen with great rapidity, giving e-keto-P-zsopropylheptoic acid (VI). This unsaturated acid is presumably formed from (3-thujaketo-lactone (III) by loss of water between the hydroxyl group on what was the 8-carbon atom of terpinolene and an adjacent hydrogen atom attached to carbon 9. CMe 9h2 9H ch2 ch2 c CMe2 (I.) CMe-OH 9H2 (^H-OH ch2 ch2 OH CMe2*OH (II.) COMe ch2 co- CH2 CH 9 c: (mo CMe2-0 COMe / 9h2 90— CH„ CH, CMe2—O (IV.) COMe COMe / VH2 (^02h CH., CH CMe!CH2 (V.) / 9h2 9o2h ch2 ch2 9H CHMe2 (VI.) 9° H02C CH 9 CMe2-0 (VIII.) 9° H09C CH CMe2—O (IX.) 90Me 9H2 9H2 co2h (VII.) This sequence of reactions is best explained by the assumption that the first step in the oxidation is the formation of the tetrahydric alcohol (II). The formation of (3-thujaketo-lactone (III) provides direct evidence of the addition of hydroxyl groups at carbon atoms 4 and 8 and the addition of hydroxyl groups at 1 and 2 is in harmony with what takes place in the case of limonene, where the trihydric alcohol, 1:2: 8-trihydroxyterpan, was isolated as an intermediate product. “ Origanene.”—It was suggested {Ann. Reports, 1908, 5, 100) that this terpene, which Pickles (J., 1908, 93, 866) regarded as' A1:3-p-menthadiene, is a-terpinene, for which this formula is now generally accepted. That suggestion ignores the fact that “ ori¬ ganene ” yields a nitrosyl chloride, m. p. 91—94°, a nitrolpiperidide,