The oils of most Eucalypts growing as "Mallees" contain one or more of these aldehydes, and these species are thus shown to be closely associated with the members of the "Box" group.

Eucalyptus Woollsiana, a species growing in the western portion of New South Wales, also contains these aldehydes in quantity, and in working out this species no less than six different distillations were made on material from various localities where it grows plentifully. These results will be found recorded under that species.

The prepared composite aldehydes, separated by sodium carbonate from the crystallised combination with sodium bisulphite, had the following specific rotations for the following species: -

So that no regularity in optical rotations is observed with the prepared aldehydes from different Eucalypts.

Experimental

940 c.c. of the crude oil of E. hemiphloia, containing some phellandrene, distilled in March, 1920, was first agitated with a 5 per cent. solution of sodium hydrate to remove the phenols. (From these phenols pure crystallised australol was prepared.) It was afterwards distilled, and the portion boiling below 1900 C. separated. The remainder was repeatedly shaken with a 35 per cent, solution of sodium bisulphite for six hours, the crystalline portion pumped off, purified by washing with ether-alcohol, and decomposed by sodium carbonate. The purified sodium sulphite compound weighed 49 grams, from which 24 c.c. of aldehyde were obtained. This had specific gravity at 240 C. = 0.970; optical rotation aD - 200 C, and refractive index at 200 C. = 1.5222.

It was then distilled under reduced pressure, when 90 per cent. of the whole boiled at 106-108° C. at 10 millimetres pressure. This portion had the following constants: - Specific gravity at I5°C. = 0.9767; rotation aD - 20.1°, and refractive index at 200 = 1.5232. The hydrazone melted at 126-1270 C, and the semicarbazone at 210-211°. This aldehyde evidently consisted largely of cuminal, the optical activity being due to the aromadendral.

In an attempt to separate the lævo-rotatory aromadendral all but 5 c.c. were lost. This portion, however, gave constants even more closely approaching those for cuminal, and the rotation was only aD - 50.

The aqueous portion separated from the crystalline compound was treated with sodium carbonate solution, and the separated aldehyde extracted with ether. In this way 5 c.c. of aldehyde were obtained, and although consisting largely of aromadendral, yet it also contained cuminal, as is shown from the following figures: - It had specific gravity at 150 C. = 0.9703; rotation aD - 28.5°, and refractive index at 20° - 1.5108. The semicarbazone melted at 204-2050 C.

The remaining aqueous solution was then decomposed by treating with 10 per cent. solution of sodium hydrate, and the aldehyde extracted with ether; no less than 43 c.c. of aldehyde were obtained in this way. This had specific gravity at 150 C. = 0.9471; rotation aD - 98.4°, and refractive index at 20° = 1.4864. It was then distilled under reduced pressure, when 90 per cent. came over at 101.1020 C. at 10 millimetres. It had the following constants: -

(Both the oxime and hydrazone were produced by the highly rotatory aldehyde allied to phellandral, because those formed with cryptal are liquid.)

The aldehyde thus prepared was then shaken with a 35 per cent. solution of neutral sodium sulphite at room temperature (20° C), repeatedly neutralising the separated sodium hydrate with standard acid, until combination was complete. The uncombined aldehyde was then removed by ether, dried and weighed.

This result was very satisfactory for an aldehyde with the C10Hl5O molecule. The combined aldehyde was regenerated from the aqueous solution by sodium hydrate, extracted with ether and prepared in the usual way. The constants, with varying degrees in optical rotation with the different species, are those for cryptal.

The oxime and hydrazone were both liquid, and so far we have not succeeded in forming these in a satisfactory crystallised condition.

The aldehyde which did not combine with neutral sodium sulphite in the cold, and was not decomposed by sodium carbonate, had a remarkably high rotation. It gave the following constants: -

These figures closely agree with those given for phellandral; the aldehyde had evidently the C10Hl6O molecule with one double linkage.

On the completion of the above work it was decided to procure fresh material of E. hemiphloia, for purposes of comparison. As the date of collection was less than four weeks from the above, but little differences were observed from those already given, except that the cuminal fraction was but - 1.8°. The same mode of procedure was adopted throughout as in the previous case. The aldehyde cryptal, when finally separated, gave almost identical results with the previous sample, and are recorded here for purposes of comparison: -

The oximes and hydrazones were liquid in both cases.

The molecular refraction calculated for a C10Hl6O aldehyde with one double bond is 45.82; found 45.99.

The combustion results for cryptal were as follows: - 0.1729 gram gave 0.4982 gram. CO2, and 0.1638 gram. H2O. C. = 7858, and H. = 10.52 per cent C10Hl6O requires 78.94 C. and 10.53 H.

The total amount of aldehydes belonging to this group, extracted from the crude oil of E. hemiphloia, was equal to 10 per cent.