— 33 — 



For the purpose of isolating the aldehyde, which process was 

 carried out in the usual manner with the help of the bisulphite 

 compound, Baker and Smith used the portions of the oil boiling 

 above 190 . The yield of aromadendral was 1,6 °/ . The pure al- 

 dehyde is a bright yellow mobile liquid, with a peculiar odour; 

 ^22° 0,95325; a D2 2° — 86,2°; W D 22° — 9°>43°; boiling point 218 to 

 2 1 9 with partial decomposition. Of derivatives there were produced, 

 the oxime (melting point 86°), the hydrazone (melting point 104 to 

 105 , when prepared in acetic solution; the hydrazone prepared in 

 solution of alcohol or petroleum ether melted slightly higher, but was 

 less stable), the naphthocinchoninic acid (melting point 245 to 246 ). 

 Combustions gave figures corresponding with the formula C 9 H 12 O. 



The compound readily absorbs bromine with formation of a liquid 

 dibromide (d22° 1,4302), which on being heated splits off hydrobromic 

 acid, when probably a monobromide remains behind. From the high 

 specific gravity, the high refractive index, and the other behaviour, 

 it may be concluded that the aldehyde represents a cyclic compound. 

 The molecular refraction calculated from di 6 o 0,9576 and n Di6° I ;5I4 I ? 

 according to Lorenz-Lorentz, is 42,76; for C 9 H 12 0, the result 

 (assuming 3 double linkings) is 42,529. 



By oxidation with potassium bichromate and sulphuric acid, aroma- 

 dendral was converted into an unsaturated monobasic acid (aroma - 

 dendrinic acid, C 9 H 12 2 ). The acid dried at 105 to no°, melted 

 between 137 and 13 8°, when simultaneously a slight sublimation could 

 be observed; the air-dry crystals, however, melted at a lower tem- 

 perature, but had no constant melting point. The acid is almost 

 insoluble in cold, slightly soluble in hot water, but dissolves readily 

 in alcohol and ether. Combustion, and determination of molecular 

 weight and of silver of the silver salt, gave values corresponding to 

 the formula C 9 H 12 2 . The oxidation products of aromadendral are 

 to be examined still further later on, chiefly with the view of solving 

 the problem of the structure of aromadendral. 



The observation that the aldehydes isolated from the various 

 eucalyptus oils showed strongly divergent rotations, led Baker and 

 Smith to the view that aromadendral occurs in both optical modi- 

 fications, which also appears to follow from the similarity of the oximes, 

 hydrazones and naphthocinchoninic acids of the differently rotating 

 aromadendrals. On the other hand the authors consider it also 

 possible that in a few cases, as for example in that of oil of E. hemi- 

 phloia, cuminic aldehyde is present, which for the rest is undoubtedly 

 the case in accordance with our above-mentioned examinations. 



In a work which may be taken to represent a supplement to 

 R. T. Baker and H. G. Smith's work "A research on the Eucalypts, 



3 



