486 



given to this laevorotatory aldehyde by one of us when it was 

 first announced (Roy. Soc. N.S.W., 1900, p. 286). 



In Schimmel & Co.'s work, above quoted, p. 449, appears- 

 a description of a tetrahydroaromatic aldehyde (Phellandral) 

 obtained from water fennel oil. Tt thus appears that the 

 three aldehyhes — cumin aldehyde, aromaclendral, and phel- 

 landral — form the series C ]0 H 12 O, C 10 H :4 O, and C 10 H 1( .O. 

 The two last show optical activity, the former is inactive.. 



That both active forrn^ of aromaclendral occur in Euca- 

 lyptus oils is suggested from the fact that the degree of 

 rotation varies greatly in the several species which contain 

 it, although the predominant dextrorotatory form has not yet 

 been isolated; also that the oxime prepared with the aldehyde 

 extracted from the mixed high-boiling fractions of numerous 

 Eucalyptus oils in which it occurs, melted at 84-85° C, which 

 is the melting point for the oxime of aromadendral. That 

 aromadendral is a definite chemical substance is demonstrated 

 by the uniformity shown b}^ the aldehyde when prepared from 

 Eucalyptus species growing many hundreds of miles apart. 



Aromadendral was extracted from the higher-boiling- 

 portion of the oil of E. rostrata by the aid of sodium bisul- 

 phite in the usual manner. When purified it had an odour 

 reminding of cumin aldehyde, was almost colourless, being 

 slightly yellow in appearance, and was highly laevorotatory. 

 The specific gravity at 20° C. = 0'9534 : specific rotation,. 

 Md- 73-94°; refractive index at 20° = 1-5066; the oxime 

 melted at 84-85°, and the phenylhydrazone at 105-106° C. 

 By arranging these results in tabulated form with those of 

 cuminaldehyde the differences appear distinctly marked. The 

 corresponding figures for phellandral, as given by Schimmel 

 and Co., are also added for comparison: — 



d 15° C. ... ... 



Optical rotation 

 m.p. oxime 

 m. p. phenylhydra- 

 zone 



Ref. index at 20° 



Cuminaldehyde. 



0-9818 



Nil 



58-59° 



126-127° 



Aromadendral. 



0-9569 

 [a] D -73'94 c 



84-85° 



105-106° 

 1-5066 



Phellandral. 



0-9445 

 a D -36'30 c 



87-88° 



122-123° 

 1-4911 



For further reference in connection with aromadendral 

 see our work, "Research on the Eucalypts," 1902, p. 218. 



