318 VII. ACIDS, AMIDES, ALDEHYDES AND HYDROCARBONS 



tion in the tissues, and it is believed that they are normal metabolic prod- 

 ucts of fats. Anchel and Waelsch^^^ reported that the aldehydes isolated 

 from beef muscle, beef brain, rat muscle, and rat brain (which were chiefly 

 Cie and Cis compounds) were similar, as judged from the analytical results 

 of their derivatives. They were separated in amounts varying between 

 0.05 and 0.2% of the tissue used. 



Ehrlich and Waelsch"* attempted to ascertain whether or not the fatty 

 aldehydes are intermediates in the oxidation of fatty acids. On the basis 

 of tests in which deuterium was fed to rats on a low-fat diet, or to animals 

 receiving deuterio-fats, it was found that the deuterium content of the 

 aldehydes was invariably less than that of the corresponding fatty acids. 

 This was taken to indicate that the fatty aldehydes are not involved in the 

 over-all synthesis or transport of fatty acids, but rather are associated 

 with some special aspects of fatty acid metabohsm. The fatty aldehydes 

 appear to be in highest concentration in the skin, as indicated by the high 

 deuterium content of the unsaponifiable fraction of these lipids; the pro- 

 portion of the unsaponifiable fraction was much lower in the muscle lipids. 



The fatty aldehydes have also been found in the plant kingdom. Thus, 

 the Cs and Cg aldehydes, octanal (CHs- (CH2)6-CHO) andnonanal (CHs-- 

 (CH2)7-CHO), are well-known components of essential oils. Decanal 

 (CH3-(CH2)8-CHO) is present in definite quantities in coriander oil,'^^-^'^ 

 and dodecanal, or lauric aldehyde (CH3-(CH2)io-CHO), has been isolated 

 from the oil obtained from the lily of the valley.'" An aldehyde contain- 

 ing eighteen carbons was prepared from the pulp of olives by Marcelet.^'* 

 Some of the floral odors can be traced to the shorter-chain aldehydes, each 

 of which has its own characteristic aroma. In some cases these are un- 

 saturated, as, for example, 2.6-nonadienal, CH3 -0112 -CHrCH -0112 •- 

 CH2 • CH : CH • CHO, which occurs in violet leaf oil. "^ Information on the 

 chemistry of the fatty aldehydes is to be found in The Lipids, Vol. I, pages 

 124 to 132. 



113 M. Anchel and H. Waelsch, /. Biol. Chem., 145, 605-613 (1943). 



114 G. Ehrlich and H. Waelsch, J. Biol. Chem., 163, 195-202 (1946). 



1'^ P. P. Shorvgin and V. P. Osipova, Sintezy Dushistijkh Veshchestv., Sbornik Statei, 

 1939, 246-247; ^Khim. Referat. Zhur., 1940, No. 4,117; Chem. Abst., 36, 3781 (1942). 



11^ L. Y. Bryusova, R. Y. Shagalova, and N. Novikova, Sintezy Dushistykh Vesh- 

 chestv., Sbornik Sta'H, 1939, 247-252; Khim. Referat. Zhur., 1940, No. 117-118; Chem. 

 Abst., 36,3781(19^2). 



1" W. Hannemann, Deuc. Parfihn.-Ztg., 9, No. 8/9, 7 (Apr. 15, 1923); Chimie & Indus- 

 trie, 11,941 il92'i). 



118 H. Marcelet, Compl. rend., 206, 529-530 (1938). 



119 E. Spath and F. Kesztler, Ber., 67B, 1496-1500 (1934). 



