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Volume 43, 1910
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Art. VIII.—Studies on the Chemistry of the New Zealand Flora.

By T. H. Easterfield, Victoria College, Wellington.

[Read before the Wellington Philosophical Society, 5th October, 1910.]

Part IV.—The Chemistry of the Podocarpi.

The present paper summarizes, for the use of New Zealand readers, work which has been carried on for several years in the Victoria College laboratories on various species of New Zealand Podocarpi. The full details have in part already appeared in the “Transactions of the Chemical Society,” and others will shortly be forwarded for publication in that journal. These details are of too technical a nature to be of interest to any except the highly trained specialist, who can readily refer to the journal in question, which is taken in the library of each of the University Colleges.

(1.) The Miro (Podocarpus ferrugineus).

The miro appears to be the only New Zealand member of the family which weeps drops of resin when the bark is incised (Ueberwallungsharz). The resin thus obtained is valued by bushmen for the treatment of cuts and sores. A quantity of this resin collected in Westland was steam-distilled, and the volatile oil resulting from this process was dried and distilled several times in contact with metallic sodium. The highly refractive colourless oil was proved by analysis to have the formula C10H16, and the boiling-point, specific gravity, specific rotation, and refractive index showed conclusively that the substance was a mixture of dextro- and laevo-rotary pinene.

The water in which the resin had been boiled was only faintly acid, and contained traces only of matter in solution.

The non-volatile portion of the resin was neutral in reaction, and under went no hydrolysis when boiled with alcoholic potash; it therefore contains neither esters nor lactones. After drying it can be distilled without decomposition under reduced pressure (15-20mm.). The distillate sets on cooling to a glassy mass which has hitherto resisted all attempts to make it crystallize. The substance has a characteristic smell, recalling that of cannabinol, and is easily soluble in all ordinary organic solvents. Analyses of different preparations agree with the formula C13H18O.

(2.) The Kahikatea (Podocarpus dacrydioides).

It is well known that large logs of white-pine are frequently flawed by heart-shakes filled to a greater or less extent with a hard white or yellowish deposit, which also saturates and hardens the woody tissue in the neighbourhood of the cracks. A quantity of this deposit was dissolved in alcohol and crystallized by the cautious addition of water until a permanent opalescence resulted. In a few hours the whole solution was filled with colourless crystals, which when completely purified melted at 192° C., showed a specific rotation of + 136°, and upon analysis and titration gave numbers agreeing sharply with the formula C17H22O3. This is the formula for podocarpic acid discovered by Oudemans (“Annalen der Chemie,” 1873, vol. 170, p. 213) in the heart-resin of Podocarpus cupressinus var. imbricatus (a tree common on the mountains of Java at a height of 4,000ft. and up wards), and not since recorded in any other plant. By the kindness of

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Dr. Treub, Director of the Royal Botanical Gardens at Buitenzorg, I have been supplied with a sample of this resin, and have prepared podocarpic acid from it. The acid agreed in all physical constants with the acid from kahikatea; and the lower melting-point of podocarpic acid given by Oudemans (188°-189°) is probably due to the difference in the conditions under which the determination was carried out.

In the investigation of the miro and kahikatea I have been ably assisted by Miss A. I. Slowey, M.A.

(2A.) The Rimu (Dacrydium cupressinum): a Correction.

The close resemblance between the acids of red and white pine has caused Mr. Aston to re-examine the acid prepared from the former, which was previously described under the name “rimuic acid” (Trans. N.Z. Inst., 1903, vol. 36, p. 483). Careful comparison of the physical constants and titration values has shown that podocarpic and rimuic acid are identical, so that the latter name should be erased from chemical literature. At the same time it should be pointed out that the difference between the percentage composition of an acid of the formula C16H20O3, ascribed to rimuic acid, and the formula for podocarpic acid (C17H22O3) is so small (0·6 percent. in the carbon and 0·3 percent. in the hydrogen) that titration can alone settle the question of the correct formula. The titration values show with certainty that Oudeman's formula is the correct one.

It is not without interest that trees whose external characters have led to the nomenclature Dacrydium cupresinum, Podocarpus cupressinus, and Podocarpus dacrydioides should be characterized by containing the same acid, whilst this acid is absent in the other species of Podocarpus and Dacrydium which have hitherto received the attention of the chemist.

(3.) The Matai (Podocarpus spicatus).

(In conjunction with James Bee, M.A., M.Sc.)

In the matai (mai, or black-pine) heart-shakes are not nearly so common or so large as in the rimu and kahikatea. When they do occur, however, well-formed radiating groups of crystals may often be detected in the yellow deposit within the cracks. It was expected that this material would also be found to consist of podocarpic acid. The substance was found, however, to be rather sparingly soluble in cold alcohol, whereas podocarpic acid dissolves easily. From hot alcohol the substance separated on cooling in crystals containing alcohol of crystallization, melting at 77°-78°, and having the formula C19H20O61C2H6O. After removing the alcohol of crystalization the compound melts at 119°, shows a specific rotation of +4·89°, crystallizes from 60 percent. acetic acid in large prisms, and is intensely soluble in acetone, insoluble in light petroleum. The alcoholic solution is coloured green by the addition of an aqueous solution of ferric chloride. Upon distillation a strong smell of eugenol is produced. As regards chemical constitution, two of the oxygen atoms are present as hydroxy groups and so that the formula may be rewritten C16H12(OH)2(O CH3)2CO O—. The compound yields well-characterized monacety1, dibenzoy1, and sulphonic acid derivatives. Matai resinolic acid, C16H13(OH)2(O CH3)2CO2H, has also been prepared; it crystallizes with 3 molecules of water of crystallization, and is reconverted to the lactone if boiled with water or by the action of cold dilute mineral acids.

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Matai-resinol is isomeric with pino-resinol, the crystalline constituent of the exudation resins of Pinus laricio and Picea vulgaris isolated by Max Bamberger (Monatshefte, 1894, vol. 15, p. 505). Pino-resinol also contains two methoxy and two hydroxy groups, but experiments do not appear to have been made in order to ascertain if the substance is lactonic in character. Pino-resinol differs from matai-resinol in having a higher melting-point and in yielding a very sparingly soluble potassium-salt.

(4.) The Totara (Podocarpus totara).

No heart-resin can be observed in totara logs, but a crystalline “bloom” can often be detected on totara boards a few hours after leaving the planing-machine. To investigate this substance, 1 cwt. of totara sawdust was extracted with alcohol and the spirit removed by distillation. The residue was an amorphous mass easily soluble in organic solvents, but crystallizing with great difficulty from most menstrua. By spontaneous evaporation of the solution in light petroleum the substance is easily obtained in large crystals. The compound is neutral in reaction, and is not hydrolized by alcoholic potash; it distils under diminshed pressure without decomposition. Analysis supports the formula C18H26O.

In the investigation of this substance I have received much help from Mr. George Bagley.

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